ETC AN2131

EZ-USB
Technical Reference
Manual
Cypress Semiconductor
3901 North First Street
San Jose, CA 95134
Tel.: (800) 858-1810 (toll-free in the U.S.)
(408) 943-2600
www.cypress.com
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EZ-USB Technical Reference Manual, Version
1.10
Copyright © 2000, 2001, 2002
Cypress Semiconductor Corporation
All rights reserved.
List of Trademarks
Cypress, the Cypress Logo, EZ-USB, Making USB Universal, Xcelerator, and ReNumeration are
trademarks or registered trademarks of Cypress Semiconductor Corporation. Macintosh is a registered trademark of Apple Computer, Inc. Windows is a registered trademark of Microsoft Corporation. I²C is a registered trademark of Philips Electronics. All other product or company names used
in this manual may be trademarks, registered trademarks, or servicemarks of their respective owners.
Table of Contents
Chapter 1. Introducing EZ-USB
1.1
1.2
1.3
1.4
1.5
Introduction....................................................................................................................................1-1
EZ-USB Block Diagrams ...............................................................................................................1-2
The USB Specification ..................................................................................................................1-3
Tokens and PIDs ...........................................................................................................................1-3
Host is Master ...............................................................................................................................1-5
1.5.1 Receiving Data from the Host..........................................................................................1-5
1.5.2 Sending Data to the Host.................................................................................................1-6
1.6 USB Direction................................................................................................................................1-6
1.7 Frame ............................................................................................................................................1-6
1.8 EZ-USB Transfer Types ................................................................................................................1-6
1.8.1 Bulk Transfers..................................................................................................................1-6
1.8.2 Interrupt Transfers ...........................................................................................................1-7
1.8.3 Isochronous Transfers .....................................................................................................1-7
1.8.4 Control Transfers .............................................................................................................1-8
1.9 Enumeration ..................................................................................................................................1-8
1.10 The USB Core .............................................................................................................................1-9
1.11 EZ-USB Microprocessor............................................................................................................1-10
1.12 ReNumeration™........................................................................................................................1-11
1.13 EZ-USB Endpoints ....................................................................................................................1-11
1.13.1 EZ-USB Bulk Endpoints...............................................................................................1-12
1.13.2 EZ-USB Control Endpoint Zero ...................................................................................1-12
1.13.3 EZ-USB Interrupt Endpoints ........................................................................................1-12
1.13.4 EZ-USB Isochronous Endpoints ..................................................................................1-13
1.14 Fast Transfer Modes .................................................................................................................1-13
1.15 Interrupts ...................................................................................................................................1-13
1.16 Reset and Power Management.................................................................................................1-14
1.17 EZ-USB Product Family ............................................................................................................1-15
1.18 Pin Descriptions ........................................................................................................................1-15
Chapter 2. EZ-USB CPU
2.1
2.2
2.3
2.4
2.5
Introduction....................................................................................................................................2-1
8051 Enhancements .....................................................................................................................2-1
EZ-USB Enhancements ................................................................................................................2-2
EZ-USB Register Interface............................................................................................................2-2
EZ-USB Internal RAM ...................................................................................................................2-3
i
(Table of Contents)
2.6 I/O Ports ........................................................................................................................................2-3
2.7 Interrupts .......................................................................................................................................2-5
2.8 Power Control ...............................................................................................................................2-5
2.9 SFRs .............................................................................................................................................2-6
2.10 Internal Bus .................................................................................................................................2-7
2.11 Reset...........................................................................................................................................2-8
Chapter 3. EZ-USB Memory
3.1
3.2
3.3
3.4
Introduction ...................................................................................................................................3-1
8051 Memory ................................................................................................................................3-2
Expanding EZ-USB Memory .........................................................................................................3-4
CS# and OE# Signals ...................................................................................................................3-5
Chapter 4. EZ-USB Input/Output
4.1
4.2
4.3
4.4
4.5
4.6
Introduction ...................................................................................................................................4-1
IO Ports .........................................................................................................................................4-2
IO Port Registers...........................................................................................................................4-5
I2C Controller ................................................................................................................................4-6
8051 I2C Controller .......................................................................................................................4-6
Control Bits....................................................................................................................................4-8
4.6.1 START.............................................................................................................................4-8
4.6.2 STOP...............................................................................................................................4-8
4.6.3 LASTRD ..........................................................................................................................4-9
4.7 Status Bits .....................................................................................................................................4-9
4.7.1 DONE ..............................................................................................................................4-9
4.7.2 ACK .................................................................................................................................4-9
4.7.3 BERR...............................................................................................................................4-9
4.7.4 ID1, ID0 .........................................................................................................................4-10
4.8 Sending I2C Data........................................................................................................................4-10
4.9 Receiving I2C Data .....................................................................................................................4-10
4.10 I2C Boot Loader ........................................................................................................................4-11
Chapter 5. EZ-USB Enumeration and ReNumeration™
5.1
5.2
5.3
5.4
5.5
5.6
5.7
ii
Introduction ...................................................................................................................................5-1
The Default USB Device ...............................................................................................................5-2
EZ-USB Core Response to EP0 Device Requests .......................................................................5-3
Firmware Load ..............................................................................................................................5-5
Enumeration Modes ......................................................................................................................5-6
No Serial EEPROM .......................................................................................................................5-7
Serial EEPROM Present, First Byte is 0xB0 .................................................................................5-8
Table of Contents
(Table of Contents)
5.8 Serial EEPROM Present, First Byte is 0xB2 .................................................................................5-9
5.9 ReNumeration‘ ............................................................................................................................5-10
5.10 Multiple ReNumerations‘ ...........................................................................................................5-11
5.11 Default Descriptor......................................................................................................................5-12
Chapter 6. EZ-USB Bulk Transfers
6.1 Introduction....................................................................................................................................6-1
6.2 Bulk IN Transfers...........................................................................................................................6-4
6.3 Interrupt Transfers .........................................................................................................................6-5
6.4 EZ-USB Bulk IN Example..............................................................................................................6-5
6.5 Bulk OUT Transfers.......................................................................................................................6-6
6.6 Endpoint Pairing ............................................................................................................................6-8
6.7 Paired IN Endpoint Status .............................................................................................................6-9
6.8 Paired OUT Endpoint Status .........................................................................................................6-9
6.9 Using Bulk Buffer Memory...........................................................................................................6-10
6.10 Data Toggle Control ..................................................................................................................6-11
6.11 Polled Bulk Transfer Example ...................................................................................................6-12
6.12 Enumeration Note .....................................................................................................................6-13
6.13 Bulk Endpoint Interrupts ............................................................................................................6-13
6.14 Interrupt Bulk Transfer Example................................................................................................6-15
6.15 Enumeration Note .....................................................................................................................6-19
6.16 The Autopointer.........................................................................................................................6-20
Chapter 7. EZ-USB Endpoint Zero
7.1 Introduction....................................................................................................................................7-1
7.2 Control Endpoint EP0....................................................................................................................7-2
7.3 USB Requests ...............................................................................................................................7-5
7.3.1 Get Status........................................................................................................................7-6
7.3.2 Set Feature ....................................................................................................................7-10
7.3.3 Clear Feature.................................................................................................................7-11
7.3.4 Get Descriptor................................................................................................................7-12
7.3.4.1 Get Descriptor-Device ........................................................................................7-14
7.3.4.2 Get Descriptor-Configuration .............................................................................7-15
7.3.4.3 Get Descriptor-String .........................................................................................7-15
7.3.5 Set Descriptor ................................................................................................................7-16
7.3.6 Set Configuration ...........................................................................................................7-18
7.3.7 Get Configuration...........................................................................................................7-18
7.3.8 Set Interface ..................................................................................................................7-19
7.3.9 Get Interface ..................................................................................................................7-20
7.3.10 Set Address .................................................................................................................7-20
7.3.11 Sync Frame .................................................................................................................7-21
7.3.12 Firmware Load.............................................................................................................7-22
Table of Contents
iii
(Table of Contents)
Chapter 8. EZ-USB Isochronous Transfers
8.1 Introduction ...................................................................................................................................8-1
8.2 Isochronous IN Transfers ..............................................................................................................8-2
8.2.1 Initialization......................................................................................................................8-2
8.2.2 IN Data Transfers ............................................................................................................8-3
8.3 Isochronous OUT Transfers ..........................................................................................................8-3
8.3.1 Initialization......................................................................................................................8-4
8.3.2 OUT Data Transfer ..........................................................................................................8-5
8.4 Setting Isochronous FIFO Sizes ...................................................................................................8-5
8.5 Isochronous Transfer Speed.........................................................................................................8-8
8.6 Fast Transfers ...............................................................................................................................8-9
8.6.1 Fast Writes ....................................................................................................................8-10
8.6.2 Fast Reads ....................................................................................................................8-10
8.7 Fast Transfer Timing ...................................................................................................................8-11
8.7.1 Fast Write Waveforms ...................................................................................................8-12
8.7.2 Fast Read Waveforms...................................................................................................8-13
8.8 Fast Transfer Speed ...................................................................................................................8-14
8.9 Other Isochronous Registers ......................................................................................................8-15
8.9.1 Disable ISO ...................................................................................................................8-15
8.9.2 Zero Byte Count Bits .....................................................................................................8-16
8.10 ISO IN Response with No Data.................................................................................................8-16
8.11 Using the Isochronous FIFOs ...................................................................................................8-17
Chapter 9. EZ-USB Interrupts
9.1 Introduction ...................................................................................................................................9-1
9.2 USB Core Interrupts......................................................................................................................9-2
9.3 Wakeup Interrupt...........................................................................................................................9-2
9.4 USB Signaling Interrupts ...............................................................................................................9-3
9.5 SUTOK, SUDAV Interrupts ...........................................................................................................9-8
9.6 SOF Interrupt ................................................................................................................................9-8
9.7 Suspend Interrupt..........................................................................................................................9-9
9.8 USB RESET Interrupt ...................................................................................................................9-9
9.9 Bulk Endpoint Interrupts ................................................................................................................9-9
9.10 USB Autovectors .........................................................................................................................9-9
9.11 Autovector Coding.....................................................................................................................9-11
9.12 I2C Interrupt...............................................................................................................................9-12
9.13 I2C Registers .............................................................................................................................9-13
iv
Table of Contents
(Table of Contents)
Chapter 10. EZ-USB Resets
10.1 Introduction................................................................................................................................10-1
10.2 EZ-USB Power-On Reset (POR) ..............................................................................................10-1
10.3 Releasing the 8051 Reset .........................................................................................................10-3
10.3.1 RAM Download............................................................................................................10-4
10.3.2 EEPROM Load ............................................................................................................10-4
10.3.3 External ROM ..............................................................................................................10-4
10.4 8051 Reset Effects ....................................................................................................................10-4
10.5 USB Bus Reset .........................................................................................................................10-6
10.6 EZ-USB Disconnect ..................................................................................................................10-7
10.7 Reset Summary.........................................................................................................................10-8
Chapter 11. EZ-USB Power Management
11.1
11.2
11.3
11.4
Introduction................................................................................................................................11-1
Suspend ....................................................................................................................................11-2
Resume .....................................................................................................................................11-3
Remote Wakeup........................................................................................................................11-4
Chapter 12. EZ-USB Registers
12.1 Introduction................................................................................................................................12-1
12.2 Bulk Data Buffers ......................................................................................................................12-3
12.3 Isochronous Data FIFOs ...........................................................................................................12-4
12.4 Isochronous Byte Counts ..........................................................................................................12-5
12.5 CPU Registers...........................................................................................................................12-6
12.6 Port Configuration .....................................................................................................................12-7
12.7 Input-Output Port Registers.......................................................................................................12-9
12.8 Isochronous Control/Status Registers.....................................................................................12-11
12.9 I2C Registers ...........................................................................................................................12-13
12.10 Interrupts ...............................................................................................................................12-15
12.11 Endpoint 0 Control and Status Registers ..............................................................................12-21
12.12 Endpoint 1-7 Control and Status Registers ...........................................................................12-22
12.13 Global USB Registers ...........................................................................................................12-28
12.14 Fast Transfers .......................................................................................................................12-34
12.15 SETUP Data..........................................................................................................................12-36
12.16 Isochronous FIFO Sizes........................................................................................................12-37
Table of Contents
v
(Table of Contents)
Chapter 13. EZ-USB AC/DC Parameters
13.1 Electrical Characteristics ...........................................................................................................13-1
13.1.1 Absolute Maximum Ratings.........................................................................................13-1
13.1.2 Operating Conditions...................................................................................................13-1
13.1.3 DC Characteristics.......................................................................................................13-1
13.1.4 AC Electrical Characteristics .......................................................................................13-2
13.1.5 General Memory Timing ..............................................................................................13-2
13.1.6 Program Memory Read ...............................................................................................13-2
13.1.7 Data Memory Read .....................................................................................................13-2
13.1.8 Data Memory Write......................................................................................................13-3
13.1.9 Fast Data Write............................................................................................................13-3
13.1.10 Fast Data Read .........................................................................................................13-3
Chapter 14. EZ-USB Packaging
14.1 44-Pin PQFP Package ..............................................................................................................14-1
14.2 80-Pin PQFP Package ..............................................................................................................14-3
14.3 48-Pin TQFP Package ..............................................................................................................14-5
Appendix A
CPU Introduction
A.1 Introduction ................................................................................................................................ A - 1
A.2 8051 Enhancements .................................................................................................................. A - 2
A.3 Performance Overview .............................................................................................................. A - 2
A.4 Software Compatibility ............................................................................................................... A - 4
A.5 803x/805x Feature Comparison ................................................................................................ A - 4
A.6 EZ-USB/DS80C320 Differences ................................................................................................ A - 4
A.6.1 Serial Ports ..................................................................................................................... A - 5
A.6.2 Timer 2 ........................................................................................................................... A - 5
A.6.3 Timed Access Protection ............................................................................................... A - 5
A.6.4 Watchdog Timer ............................................................................................................. A - 5
A.6.5 Power Fail Detection ...................................................................................................... A - 5
A.6.6 Port I/O ........................................................................................................................... A - 5
A.6.7 Interrupts ........................................................................................................................ A - 6
A.7 EZ-USB Register Interface ........................................................................................................ A - 6
A.8 EZ-USB Internal RAM ................................................................................................................ A - 6
A.9 I/O Ports ..................................................................................................................................... A - 7
A.10 Interrupts .................................................................................................................................. A - 7
A.11 Power Control .......................................................................................................................... A - 8
A.12 Special Function Registers (SFR) ........................................................................................... A - 8
A.13 External Address/Data Buses ................................................................................................ A - 12
A.14 Reset ..................................................................................................................................... A - 12
vi
Table of Contents
(Table of Contents)
Appendix B
CPU Architectural Overview
B.1 Internal Data RAM ...................................................................................................................
B.1.1 The Lower 128 .............................................................................................................
B.1.2 The Upper 128 .............................................................................................................
B.1.3 SFR (Special Function Register) Space .......................................................................
B.2 Instruction Set ..........................................................................................................................
B.2.1 Instruction Timing .........................................................................................................
B.2.2 Stretch Memory Cycles (Wait States) ..........................................................................
B.2.3 Dual Data Pointers .......................................................................................................
B.2.4 Special Function Registers ...........................................................................................
B - 13
B - 13
B - 14
B - 14
B - 14
B - 19
B - 19
B - 20
B - 21
Appendix C
EZ-USB Peripherals
C.1 Introduction ..............................................................................................................................
C.2 Timers/Counters ......................................................................................................................
C.2.1 803x/805x Compatibility ...............................................................................................
C.2.2 Timers 0 and 1 .............................................................................................................
C.2.2.1 Mode 0, 13-Bit Timer/Counter — Timer 0 and Timer 1 .................................
C.2.2.2 Mode 1, 16-Bit Timer/Counter — Timer 0 and Timer 1 .................................
C.2.2.3 Mode 2, 8-Bit Counter with Auto-Reload — Timer 0 and Timer 1 .................
C.2.2.4 Mode 3, Two 8-Bit Counters — Timer 0 Only ................................................
C.2.3 Timer Rate Control .......................................................................................................
C.2.4 Timer 2 .........................................................................................................................
C.2.4.1 Timer 2 Mode Control ....................................................................................
C.2.5 Timer 2 — 16-Bit Timer/Counter Mode ........................................................................
C.2.5.1 Timer 2 — 16-Bit Timer/Counter Mode with Capture ....................................
C.2.6 Timer 2 — 16-Bit Timer/Counter Mode with Auto-Reload ............................................
C.2.7 Timer 2 — Baud Rate Generator Mode .......................................................................
C.3 Serial Interface .........................................................................................................................
C.3.1 803x/805x Compatibility ...............................................................................................
C.3.2 Mode 0 .........................................................................................................................
C.3.3 Mode 1 .........................................................................................................................
C.3.3.1 Mode 1 Baud Rate .........................................................................................
C.3.3.2 Mode 1 Transmit ............................................................................................
C.3.4 Mode 1 Receive ...........................................................................................................
C.3.5 Mode 2 .........................................................................................................................
C.3.5.1 Mode 2 Transmit ............................................................................................
C.3.5.2 Mode 2 Receive .............................................................................................
C.3.6 Mode 3 .........................................................................................................................
C.4 Interrupts ..................................................................................................................................
C.5 Interrupt-Control SFRs .............................................................................................................
C.5.1 803x/805x Compatibility ...............................................................................................
Table of Contents
C - 23
C - 23
C - 23
C - 24
C - 24
C - 25
C - 27
C - 28
C - 29
C - 30
C - 31
C - 32
C - 32
C - 32
C - 33
C - 34
C - 35
C - 36
C - 40
C - 41
C - 43
C - 43
C - 45
C - 45
C - 45
C - 46
C - 48
C - 48
C - 52
vii
(Table of Contents)
C.6 Interrupt Processing ................................................................................................................
C.6.1 Interrupt Masking .........................................................................................................
C.6.1.1 Interrupt Priorities ..........................................................................................
C.6.2 Interrupt Sampling ........................................................................................................
C.6.3 Interrupt Latency ..........................................................................................................
C - 53
C - 53
C - 54
C - 55
C - 55
Appendix D
Register Summary ......................................................................................................................... D - 59
viii
Table of Contents
List of Figures
Figure 1-1.
Figure 1-2.
Figure 1-3.
Figure 1-4.
Figure 1-5.
Figure 1-6.
Figure 1-7.
Figure 1-8.
Figure 1-9.
Figure 1-10.
Figure 1-11.
Figure 2-1.
Figure 3-1.
Figure 3-2.
Figure 3-3.
Figure 3-4.
Figure 3-5.
Figure 4-1.
Figure 4-2.
Figure 4-3.
Figure 4-4.
Figure 4-5.
Figure 4-6.
Figure 4-7.
Figure 5-1.
Figure 5-2.
Figure 5-3.
Figure 6-1.
Figure 6-2.
Figure 6-3.
Figure 6-4.
Figure 6-5.
Figure 6-6.
Figure 6-7.
Figure 6-8.
Figure 6-9.
Figure 6-10.
AN2131S (44 pin) Simplified Block Diagram ....................................................................1-2
AN2131Q (80 pin) Simplified Block Diagram ...................................................................1-3
USB Packets ....................................................................................................................1-4
Two Bulk Transfers, IN and OUT .....................................................................................1-6
An Interrupt Transfer ........................................................................................................1-7
An Isochronous Transfer ..................................................................................................1-7
A Control Transfer ............................................................................................................1-8
What the SIE Does ...........................................................................................................1-9
80-pin PQFP Package (AN2131Q) ................................................................................1-16
44-pin PQFP Package with Port B (AN2131S) ..............................................................1-17
44-pin Package with Data Bus (AN2135, and AN2136) .................................................1-18
8051 Registers .................................................................................................................2-3
EZ-USB 8-KB Memory Map - Addresses are in Hexadecimal .........................................3-1
EZ-USB 4-KB Memory Map - Addresses are in Hexadecimal .........................................3-2
Unused Bulk Endpoint Buffers (Shaded) Used as Data Memory .....................................3-3
EZ-USB Memory Map with EA=0 .....................................................................................3-4
EZ-USB Memory Map with EA=1 .....................................................................................3-6
EZ-USB Input/Output Pin .................................................................................................4-2
Alternate Function is an OUTPUT ....................................................................................4-4
Alternate Function is an INPUT ........................................................................................4-4
Registers Associated with PORTS A, B, and C ...............................................................4-5
General I2C Transfer .......................................................................................................4-6
Addressing an I2C Peripheral ..........................................................................................4-7
FC Registers ....................................................................................................................4-8
USB Control and Status Register ...................................................................................5-10
Disconnect Pin Logic ......................................................................................................5-11
Typical Disconnect Circuit (DISCOE=1) .........................................................................5-11
Two BULK Transfers, IN and OUT ...................................................................................6-1
Registers Associated with Bulk Endpoints .......................................................................6-3
Anatomy of a Bulk IN Transfer .........................................................................................6-4
Anatomy of a Bulk OUT Transfer .....................................................................................6-7
Bulk Endpoint Toggle Control ........................................................................................6-11
Example Code for a Simple (Polled) BULK Transfer .....................................................6-12
Interrupt Jump Table ......................................................................................................6-16
INT2 Interrupt Vector ......................................................................................................6-17
Interrupt Service Routine (ISR) for Endpoint 2-OUT ......................................................6-17
Background Program Transfers Endpoint 2-OUT Data to Endpoint 2-IN ......................6-18
ix
(List of Figures)
Figure 6-11.
Figure 6-12.
Figure 6-13.
Figure 6-14.
Figure 7-1.
Figure 7-2.
Figure 7-3.
Figure 7-4.
Figure 7-5.
Figure 8-1.
Figure 8-2.
Figure 8-3.
Figure 8-4.
Figure 8-5.
Figure 8-6.
Figure 8-7.
Figure 8-8.
Figure 8-9.
Figure 8-10.
Figure 8-11.
Figure 8-12.
Figure 8-13.
Figure 8-14.
Figure 8-15.
Figure 9-1.
Figure 9-2.
Figure 9-3.
Figure 9-4.
Figure 9-5.
Figure 9-6.
Figure 9-7.
Figure 9-8.
Figure 9-9.
Figure 9-10.
Figure 10-1.
Figure 11-1.
Figure 11-2.
Figure 11-3.
Figure 11-4.
Figure 12-1.
Figure 12-2.
x
Initialization Routine .......................................................................................................6-19
Autopointer Registers ....................................................................................................6-20
Use of the Autopointer ...................................................................................................6-21
8051 Code to Transfer External Data to a Bulk IN Buffer ..............................................6-22
A USB Control Transfer (This One Has a Data Stage) ....................................................7-2
The Two Interrupts Associated with EP0 CONTROL Transfers ......................................7-3
Registers Associated with EP0 Control Transfers ...........................................................7-4
Data Flow for a Get_Status Request ...............................................................................7-7
Using the Setup Data Pointer (SUDPTR) for Get_Descriptor Requests ........................7-13
EZ-USB Isochronous Endpoints 8-15 ..............................................................................8-1
Isochronous IN Endpoint Registers .................................................................................8-2
Isochronous OUT Registers .............................................................................................8-4
FIFO Start Address Format ..............................................................................................8-5
Assembler Translates FIFO Sizes to Addresses .............................................................8-7
8051 Code to Transfer Data to an Isochronous FIFO (IN8DATA) ...................................8-8
8051 MOVX Instructions ..................................................................................................8-9
Fast Transfer, EZ-USB to Outside Memory ...................................................................8-10
Fast Transfer, Outside Memory to EZ-USB ...................................................................8-10
The FASTXFR Register Controls FRD# and FWR# Strobes .........................................8-11
Fast Write Timing ...........................................................................................................8-12
Fast Read Timing ...........................................................................................................8-13
8051 Code to Transfer 640 Bytes of External Data to an Isochronous IN FIFO ............8-14
ISOCTL Register ............................................................................................................8-15
ZBCOUT Register ..........................................................................................................8-16
EZ-USB Wakeup Interrupt ...............................................................................................9-3
USB Interrupts .................................................................................................................9-4
The Order of Clearing Interrupt Requests is Important ....................................................9-6
EZ-USB Interrupt Registers .............................................................................................9-7
SUTOK and SUDAV Interrupts ........................................................................................9-8
A Start Of Frame (SOF) Packet .......................................................................................9-8
The Autovector Mechanism in Action ............................................................................9-11
I2C Interrupt Enable Bits and Registers .........................................................................9-12
I2C Control and Status Register .....................................................................................9-13
I2C Data .........................................................................................................................9-13
EZ-USB Resets ..............................................................................................................10-1
Suspend-Resume Control ..............................................................................................11-1
EZ-USB Suspend Sequence .........................................................................................11-2
EZ-USB Resume Sequence ..........................................................................................11-3
USB Control and Status Register ..................................................................................11-4
Register Description Format ..........................................................................................12-2
Bulk Data Buffers ...........................................................................................................12-3
List of Figures
(List of Figures)
Figure 12-3.
Figure 12-4.
Figure 12-5.
Figure 12-6.
Figure 12-7.
Figure 12-8.
Figure 12-9.
Figure 12-10.
Figure 12-11.
Figure 12-12.
Figure 12-13.
Figure 12-14.
Figure 12-15.
Figure 12-16.
Figure 12-17.
Figure 12-18.
Figure 12-19.
Figure 12-20.
Figure 12-21.
Figure 12-22.
Figure 12-23.
Figure 12-24.
Figure 12-25.
Figure 12-26.
Figure 12-27.
Figure 12-28.
Figure 12-29.
Figure 12-30.
Figure 12-31.
Figure 12-32.
Figure 12-33.
Figure 12-34.
Figure 12-35.
Figure 12-36.
Figure 12-37.
Figure 12-38.
Figure 12-39.
Figure 13-1.
Figure 13-2.
Figure 13-3.
Figure 13-4.
List of Figures
Isochronous Data FIFOs ...............................................................................................12-4
Isochronous Byte Counts ..............................................................................................12-5
CPU Control and Status Register ..................................................................................12-6
IO Port Configuration Registers .....................................................................................12-7
Output Port Configuration Registers ..............................................................................12-9
PINSn Registers ...........................................................................................................12-10
Output Enable Registers ..............................................................................................12-11
Isochronous OUT Endpoint Error Register ..................................................................12-11
Isochronous Control Register .......................................................................................12-12
Zero Byte Count Register .............................................................................................12-12
I2C Transfer Registers .................................................................................................12-13
Interrupt Vector Register ..............................................................................................12-15
IN/OUT Interrupt Request (IRQ) Registers ..................................................................12-15
USB Interrupt Request (IRQ) Registers .......................................................................12-16
IN/OUT Interrupt Enable Registers ..............................................................................12-17
USB Interrupt Enable Register .....................................................................................12-18
Breakpoint and Autovector Register ............................................................................12-19
IN Bulk NAK Interrupt Request Register ......................................................................12-19
IN Bulk NAK Interrupt Enable Register ........................................................................12-20
IN/OUT Interrupt Enable Registers ..............................................................................12-20
Port Configuration Registers ........................................................................................12-21
IN Control and Status Registers ...................................................................................12-24
IN Byte Count Registers ...............................................................................................12-25
OUT Control and Status Registers ...............................................................................12-26
OUT Byte Count Registers ...........................................................................................12-27
Setup Data Pointer High/Low Registers .......................................................................12-28
USB Control and Status Registers ...............................................................................12-29
Data Toggle Control Register .......................................................................................12-30
USB Frame Count High/Low Registers ........................................................................12-31
Function Address Register ...........................................................................................12-31
USB Endpoint Pairing Register ....................................................................................12-32
IN/OUT Valid Bits Register ...........................................................................................12-33
Isochronous IN/OUT Endpoint Valid Bits Register .......................................................12-33
Fast Transfer Control Register .....................................................................................12-34
Auto Pointer Registers .................................................................................................12-35
SETUP Data Buffer ......................................................................................................12-36
SETUP Data Buffer ......................................................................................................12-37
External Memory Timing ................................................................................................13-4
Program Memory Read Timing ......................................................................................13-4
Data Memory Read Timing ............................................................................................13-5
Data Memory Write Timing ............................................................................................13-5
xi
(List of Figures)
Figure 13-5.
Figure 13-6.
Figure 13-7.
Figure 13-8.
Figure 13-9.
Figure 13-10.
Figure 13-11.
Figure 13-12.
Figure 13-13.
Figure 14-1.
Figure 14-2.
Figure 14-3.
Figure 14-4.
Figure 14-5.
Figure 14-6.
Figure 14-7.
Figure 14-8.
Figure 14-9.
Figure A-1.
Figure A-2.
Figure A-3.
Figure B-1.
Figure C-1.
Figure C-2.
Figure C-3.
Figure C-4.
Figure C-5.
Figure C-6.
Figure C-7.
Figure C-8.
Figure C-9.
Figure C-10.
Figure C-11.
Figure C-12.
Figure C-13.
Figure C-14.
Figure C-15.
Figure C-16.
xii
Fast Transfer Mode Block Diagram ...............................................................................13-6
Fast Transfer Read Timing [Mode 00] ...........................................................................13-7
Fast Transfer Write Timing [Mode 00] ............................................................................13-7
Fast Transfer Read Timing [Mode 01] ...........................................................................13-8
Fast Transfer Write Timing [MODE 01] ..........................................................................13-8
Fast Transfer Read Timing [Mode 10] ...........................................................................13-9
Fast Transfer Write Timing [Mode 10] ............................................................................13-9
Fast Transfer Read Timing [Mode 11] .........................................................................13-10
Fast Transfer Write Timing [Mode 11] ..........................................................................13-10
44-Pin PQFP Package (Top View) ................................................................................14-1
44-Pin PQFP Package (Side View) ...............................................................................14-1
44-Pin PQFP Package (Detail View) .............................................................................14-2
80-Pin PQFP Package (Top View) ................................................................................14-3
80-Pin PQFP Package (Side View) ...............................................................................14-3
80-Pin PQFP Package (Detail View) .............................................................................14-4
48-Pin TQFP Package (Side View) ................................................................................14-5
48-Pin TQFP Package (Top View) .................................................................................14-5
48-Pin TQFP Package (Detail View) ..............................................................................14-6
EZ-USB CPU Features ................................................................................................. A - 1
EZ-USB to Standard 8051 Timing Comparison ............................................................ A - 3
EZ-USB Internal Data RAM .......................................................................................... A - 6
Internal Data RAM Organization ................................................................................. B - 13
Timer 0/1 - Modes 0 and 1 .......................................................................................... C - 25
Timer 0/1 - Mode 2 ...................................................................................................... C - 28
Timer 0 - Mode 3 ......................................................................................................... C - 29
Timer 2 - Timer/Counter with Capture ......................................................................... C - 32
Timer 2 - Timer/Counter with Auto Reload .................................................................. C - 33
Timer 2 - Baud Rate Generator Mode ........................................................................ C - 34
Serial Port Mode 0 Receive Timing - Low Speed Operation ....................................... C - 39
Serial Port Mode 0 Receive Timing - High Speed Operation ...................................... C - 39
Serial Port Mode 0 Transmit Timing - Low Speed Operation ...................................... C - 40
Serial Port Mode 0 Transmit Timing - High Speed Operation ..................................... C - 40
Serial Port 0 Mode 1 Transmit Timing ......................................................................... C - 44
Serial Port 0 Mode 1 Receive Timing ......................................................................... C - 44
Serial Port 0 Mode 2 Transmit Timing ......................................................................... C - 46
Serial Port 0 Mode 2 Receive Timing ......................................................................... C - 46
Serial Port 0 Mode 3 Transmit Timing ......................................................................... C - 47
Serial Port 0 Mode 3 Receive Timing ......................................................................... C - 47
List of Figures
List of Tables
Table 1-1.
Table 1-2.
Table 1-3.
Table 2-1.
Table 2-2.
Table 4-1.
Table 4-2.
Table 4-3.
Table 5-1.
Table 5-2.
Table 5-3.
Table 5-4.
Table 5-5.
Table 5-6.
Table 5-7.
Table 5-8.
Table 5-9.
Table 5-10.
Table 5-11.
Table 5-12.
Table 5-13.
Table 5-14.
Table 5-15.
Table 5-16.
Table 5-17.
Table 5-18.
Table 5-19.
Table 6-1.
Table 6-2.
Table 6-3.
Table 6-4.
Table 6-5.
Table 7-1.
Table 7-2.
Table 7-3.
Table 7-4.
USB PIDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
EZ-USB Series 2100 Family . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-15
EZ-USB Series 2100 Pinouts by Pin Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-19
EZ-USB Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5
Added Registers and Bits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6
IO Pin Functions for PORTxCFG=0 and PORTxCFG=1 . . . . . . . . . . . . . . . . . . . . . . . . 4-2
Strap Boot EEPROM Address Lines to These Values . . . . . . . . . . . . . . . . . . . . . . . . . 4-12
Results of Power-On I2C Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-12
EZ-USB Default Endpoints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2
How the EZ-USB Core Handles EP0 Requests When ReNum=0 . . . . . . . . . . . . . . . . . 5-3
Firmware Download . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-5
Firmware Upload . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-5
EZ-USB Core Action at Power-Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-6
EZ-USB Device Characteristics, No Serial EEPROM . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-7
EEPROM Data Format for “B0” Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-8
EEPROM Data Format for “B2” Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-9
USB Default Device Descriptor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-12
USB Default Configuration Descriptor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-13
USB Default Interface 0, Alternate Setting 0 Descriptor . . . . . . . . . . . . . . . . . . . . . . . . 5-13
USB Default Interface 0, Alternate Setting 1 Descriptor . . . . . . . . . . . . . . . . . . . . . . . . 5-14
USB Default Interface 0, Alternate Setting 1, Interrupt Endpoint Descriptor . . . . . . . . . 5-14
USB Default Interface 0, Alternate Setting 1, Bulk Endpoint Descriptors . . . . . . . . . . . 5-15
USB Default Interface 0, Alternate Setting 1, Isochronous Endpoint Descriptors . . . . . 5-17
USB Default Interface 0, Alternate Setting 2 Descriptor . . . . . . . . . . . . . . . . . . . . . . . . 5-18
USB Default Interface 0, Alternate Setting 1, Interrupt Endpoint Descriptor . . . . . . . . . 5-18
USB Default Interface 0, Alternate Setting 2, Bulk Endpoint Descriptors . . . . . . . . . . . 5-19
USB Default Interface 0, Alternate Setting 2, Isochronous Endpoint Descriptors . . . . . 5-20
EZ-USB Bulk, Control, and Interrupt Endpoints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1
Endpoint Pairing Bits (in the USB PAIR Register) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-8
EZ-USB Endpoint 0-7 Buffer Addresses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-10
8051 INT2 Interrupt Vector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-14
Byte Inserted by EZ-USB Core at Location 0x45 if AVEN=1 . . . . . . . . . . . . . . . . . . . . 6-14
The Eight Bytes in a USB SETUP Packet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-5
How the 8051 Handles USB Device Requests (ReNum=1) . . . . . . . . . . . . . . . . . . . . . . 7-6
Get Status-Device (Remote Wakeup and Self-Powered Bits) . . . . . . . . . . . . . . . . . . . . 7-8
Get Status-Endpoint (Stall Bits) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-8
xiii
(List of Tables)
Table 7-5.
Table 7-6.
Table 7-7.
Table 7-8.
Table 7-9.
Table 7-10.
Table 7-11.
Table 7-12.
Table 7-13.
Table 7-14.
Table 7-15.
Table 7-16.
Table 7-17.
Table 7-18.
Table 7-19.
Table 7-20.
Table 7-21.
Table 7-22.
Table 8-1.
Table 8-2.
Table 9-1.
Table 9-2.
Table 9-3.
Table 10-1.
Table 10-2.
Table 10-3.
Table 10-4.
Table 12-1.
Table 12-2.
Table 12-3.
Table 12-4.
Table 12-5.
Table 12-6.
Table 13-1.
Table 13-2.
Table 13-3.
Table 13-4.
Table 13-5.
Table 13-6.
Table 13-7.
xiv
Get Status-Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-9
Set Feature-Device (Set Remote Wakeup Bit) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-10
Set Feature-Endpoint (Stall) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-10
Clear Feature-Device (Clear Remote Wakeup Bit) . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-11
Clear Feature-Endpoint (Clear Stall) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-12
Get Descriptor-Device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-14
Get Descriptor-Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-15
Get Descriptor-String . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-15
Set Descriptor-Device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-16
Set Descriptor-Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-16
Set Descriptor-String . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-16
Set Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-18
Get Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-18
Set Interface (Actually, Set Alternate Setting AS for Interface IF) . . . . . . . . . . . . . . . . .7-19
Get Interface (Actually, Get Alternate Setting AS for interface IF) . . . . . . . . . . . . . . . . .7-20
Sync Frame . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-21
Firmware Download . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-22
Firmware Upload . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-22
Isochronous Endpoint FIFO Starting Address Registers . . . . . . . . . . . . . . . . . . . . . . . . .8-6
Addresses for RD# and WR# vs. ISODISAB bit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-15
EZ-USB Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-1
8051 JUMP Instruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-10
A Typical USB Jump Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-10
EZ-USB States After Power-On Reset (POR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10-2
EZ-USB States After a USB Bus Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10-6
Effects of an EZ-USB Disconnect and Re-connect . . . . . . . . . . . . . . . . . . . . . . . . . . . .10-7
Effects of Various EZ-USB Resets (“U” Means “Unaffected”) . . . . . . . . . . . . . . . . . . . .10-8
Bulk Endpoint Buffer Memory Addresses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12-3
Isochronous Endpoint FIFO Register Addresses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12-4
Isochronous Endpoint Byte Count Register Addresses . . . . . . . . . . . . . . . . . . . . . . . . .12-5
IO Pin Alternate Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12-8
Control and Status Register Addresses for Endpoints 0-7 . . . . . . . . . . . . . . . . . . . . . .12-23
Isochronous FIFO Start Address Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12-37
DC Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13-1
General Memory Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13-2
Program Memory Read . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13-2
Data Memory Read . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13-2
Data Memory Write . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13-3
Fast Data Write . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13-3
Fast Data Read . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13-3
List of Tables
(List of Tables)
Table A-1
Table A-2
Table A-3
Table A-4
Table A-5
Table A-6
Table A-7
Table B-1
Table B-2
Table B-3
Table B-4
Table C-1
Table C-2
Table C-3
Table C-4
Table C-5
Table C-6
Table C-7
Table C-8
Table C-9
Table C-10
Table C-11
Table C-12
Table C-13
Table C-14
Table C-15
Table C-16
Table C-17
Table C-18
Table C-19
Table C-20
Table C-21
Table C-22
Table C-23
List of Tables
EZ-USB Speed Compared to Standard 8051 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A - 3
Comparison Between EZ-USB and Other 803x/805x Devices . . . . . . . . . . . . . . . . . . . A - 4
Differences between EZ-USB and DS80C320 Interrupts . . . . . . . . . . . . . . . . . . . . . . . A - 6
EZ-USB Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A - 8
EZ-USB Special Function Registers (SFR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A - 9
Special Function Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A - 10
Special Function Register Reset Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A - 11
Legend for Instruction Set Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B - 15
EZ-USB Instruction Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B - 15
Data Memory Stretch Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B - 20
PSW Register - SFR 0xD0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B - 21
Timer/Counter Implementation Comparison . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C - 24
TMOD Register — SFR 0x89. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C - 26
TCON Register — SRF 0x88 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C - 27
CKCON (SFR 0x8E) Timer Rate Control Bits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C - 29
T2CON Register — SFR 0xC8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C - 31
Timer 2 Mode Control Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C - 31
Serial Port Modes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C - 35
Serial Interface Implementation Comparison . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C - 35
SCON0 Register — SFR 98h. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C - 37
EICON (SFR 0xD8) SMOD1 Bit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C - 37
PCON (SFR 0x87) SMOD0 Bit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C - 37
SCON1 Register — SFR C0h . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C - 38
Timer 1 Reload Values for Common Serial Port Mode 1 Baud Rates . . . . . . . . . . . . . C - 42
Timer 2 Reload Values for Common Serial Port Mode 1 Baud Rates . . . . . . . . . . . . . C - 43
EZ-USB Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C - 48
IE Register — SFR 0xA8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C - 49
IP Register — SFR 0xB8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C - 50
EXIF Register — SFR 0x91 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C - 50
EICON Register — SFR 0xD8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C - 51
EIE Register — SFR 0xE8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C - 51
EIP Register — SFR 0xF8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C - 52
Summary of Interrupt Compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C - 52
Interrupt Flags, Enables, Priority Control, and Vectors . . . . . . . . . . . . . . . . . . . . . . . . C - 54
xv
(List of Tables)
xvi
List of Tables
Chapter 1
1.1
Introducing EZ-USB
Introduction
Like a well designed automobile or appliance, a USB peripheral’s outward simplicity hides internal
complexity. There’s a lot going on “under the hood” of a USB device, which gives the user a new
level of convenience. For example:
•
A USB device can be plugged in anytime, even when the PC is turned on.
•
When the PC detects that a USB device has been plugged in, it automatically interrogates
the device to learn its capabilities and requirements. From this information, the PC automatically loads the device’s driver into the operating system. When the device is
unplugged, the operating system automatically logs it off and unloads its driver.
•
USB devices do not use DIP switches, jumpers, or configuration programs. There is never
an IRQ, DMA, MEMORY, or IO conflict with a USB device.
•
USB expansion hubs make the bus available to dozens of devices.
•
USB is fast enough for printers, CD-quality audio, and scanners.
USB is defined in the Universal Serial Bus Specification Version 1.1 (http://usb.org), a 268-page
document that describes all aspects of a USB device in elaborate detail. This EZ-USB Technical
Reference Manual describes the EZ-USB chip along with USB topics that should provide help in
understanding the Specification.
The Cypress Semiconductor EZ-USB is a compact integrated circuit that provides a highly integrated solution for a USB peripheral device. Three key EZ-USB features are:
•
The EZ-USB family provides a soft (RAM-based) solution that allows unlimited configuration and upgrades.
•
The EZ-USB family delivers full USB throughput. Designs that use EZ-USB are not limited
by number of endpoints, buffer sizes, or transfer speeds.
•
The EZ-USB family does much of the USB housekeeping in the EZ-USB core, simplifying
code and accelerating the USB learning curve.
Chapter 1. Introducing EZ-USB
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This chapter introduces some key USB concepts and terminology that should make reading the
rest of this Technical Reference Manual easier.
1.2
EZ-USB Block Diagrams
+5V
D+
D-
Serial
Interface
Engine
(SIE)
bytes
bytes
GND
USB
Connector
USB
Interface
Program &
Data
RAM
IO Ports
General
Purpose
Microprocessor
USB
Transceiver
EZ-USB
Figure 1-1. AN2131S (44 pin) Simplified Block Diagram
The Cypress Semiconductor EZ-USB chip packs the intelligence required by a USB peripheral
interface into a compact integrated circuit. As Figure 1-1 illustrates, an integrated USB transceiver
connects to the USB bus pins D+ and D-. A Serial Interface Engine (SIE) decodes and encodes
the serial data and performs error correction, bit stuffing, and other signaling-level details required
by USB, and ultimately transfers data bytes to and from the USB interface.
The internal microprocessor is enhanced 8051 with fast execution time and added features. It
uses internal RAM for program and data storage, making the EZ-USB family a soft solution. The
USB host downloads 8051 program code and device personality into RAM over the USB bus, and
then the EZ-USB chip re-connects as the custom device as defined by the loaded code.
The EZ-USB family uses an enhanced SIE/USB interface (called the “USB Core”) which has the
intelligence to function as a full USB device even before the 8051. The enhanced core simplifies
8051 code by implementing much of the USB protocol itself.
EZ-USB chips operate at 3.3V. This simplifies the design of bus-powered USB devices, since the
5V power available in the USB connector (which the USB specification allows to be as low as
4.4V) can drive a 3.3V regulator to deliver clean isolated power to the EZ-USB chip.
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+5V
D+
D-
Serial
Interface
Engine
(SIE)
bytes
bytes
GND
USB
Connector
USB
Interface
Program &
Data
RAM
General
Purpose
Microprocessor
USB
Transceiver
IO Ports
Address Bus
Data Bus
External
Memory,
FIFOS,
etc.
EZ-USB
Figure 1-2. AN2131Q (80 pin) Simplified Block Diagram
Figure 1-2 illustrates the AN2131Q, an 80-pin version of the EZ-USB family. In addition to the 24
IO pins, it contains a 16-bit address bus and an 8-bit data bus for external memory expansion.
A special fast transfer mode moves data directly between external logic and internal USB FIFOs.
The fast transfer mode, along with abundant endpoint resources, allows the EZ-USB family to support transfer bandwidths beyond the maximum required by the Universal Serial Bus Specification
Version 1.1.
1.3
The USB Specification
The Universal Serial Bus Specification Version 1.1 is available on the Internet at http://usb.org.
Published in January 1998, the specification is the work of a founding committee of seven industry
heavyweights: Compaq, DEC, IBM, Intel, Microsoft, NEC, and Northern Telecom. This impressive
list of implementers secures USB as the low to medium speed PC connection method of the future.
A glance at the USB Specification makes it immediately apparent that USB is not nearly as simple
as the customary serial or parallel port. The specification uses new terms like “endpoint,” isochronous,” and “enumeration,” and finds new uses for old terms like “configuration,” “interface,” and
“interrupt.” Woven into the USB fabric is a software abstraction model that deals with things such
as “pipes.” The specification also contains detail about the connector types and wire colors.
1.4
Tokens and PIDs
In this manual, you will read statements like, “When the host sends an IN token...” or “The device
responds with an ACK.” What do these terms mean? A USB transaction consists of data packets
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identified by special codes called Packet IDs or PIDs. A PID signifies what kind of packet is being
transmitted. There are four PID types, as shown in Table 1-1.
Table 1-1. USB PIDs
PID Type
A E
O
D N
U
D D
T
R P
C
R
C
5
D
A
T
A
1
PID Name
Token
IN, OUT, SOF, SETUP
Data
DATA0, DATA1
Handshake
ACK, NAK, STALL
Special
PRE
Payload
Data
C
R
C
1
6
A
C
K
A E
O
D N
U
D D
T
R P
C
R
C
5
D
A
T
A
0
Payload
Data
C
R
C
1
6
A
C
K
Token Packet
Data Packet
H/S Pkt
Token Packet
Data Packet
H/S Pkt
1
2
3
4
5
6
Figure 1-3. USB Packets
Figure 1-3 illustrates a USB transfer. Packet 1 is an OUT token, indicated by the OUT PID. The
OUT token signifies that data from the host is about to be transmitted over the bus. Packet 2 contains data, as indicated by the DATA1 PID. Packet 3 is a handshake packet, sent by the device
using the ACK (acknowledge) PID to signify to the host that the device received the data errorfree.
Continuing with Figure 1-3, a second transaction begins with another OUT token 4, followed by
more data 5, this time using the DATA0 PID. Finally, the device again indicates success by transmitting the ACK PID in a handshake packet 6.
Why two DATA PIDs, DATA0 and DATA1? It’s because the USB architects took error correction
very seriously. As mentioned previously, the ACK handshake is a signal to the host that the
peripheral received data without error (the CRC portion of the packet is used to detect errors). But
what if a handshake packet itself is garbled in transmission? To detect this, each side, host and
device maintains a data toggle bit, which is toggled between data packet transfers. The state of
this internal toggle bit is compared with the PID that arrives with the data, either DATA0 or DATA1.
When sending data, the host or device sends alternating DATA0-DATA1 PIDs. By comparing the
Data PID with the state of the internal toggle bit, the host or device can detect a corrupted handshake packet.
SETUP tokens are unique to CONTROL transfers. They preface eight bytes of data from which
the peripheral decodes host Device Requests.
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SOF tokens occur once per millisecond, denoting a USB frame.
There are three handshake PIDs: ACK, NAK, and STALL.
•
ACK means “success;” the data was received error-free.
•
NAK means “busy, try again.” It’s tempting to assume that NAK means “error,” but it
doesn’t. A USB device indicates an error by not responding.
•
STALL means that something unforeseen went wrong (probably as a result of miscommunication or lack of cooperation between the software and firmware writers). A device
sends the STALL handshake to indicate that it doesn’t understand a device request, that
something went wrong on the peripheral end, or that the host tried to access a resource
that isn’t there. It’s like “halt,” but better, because USB provides a way to recover from a
stall.
A PRE (Preamble) PID precedes a low-speed (1.5 Mbps) USB transmission. The EZ-USB family
supports high-speed (12 Mbps) USB transfers only, so it ignores PRE packets and the subsequent
low-speed transfer.
1.5
Host is Master
This is a fundamental USB concept. There is exactly one master in a USB system: the host computer. USB devices respond to host requests. USB devices cannot send information between
themselves, as they could if USB were a peer-to-peer topology.
Actually, there is one case where a USB device can initiate signaling without prompting from the
host. After being put into a low-power suspend mode by the host, a device can signal a remote
wakeup. But that’s the only way to “yank the host’s chain.” Everything else happens because the
host makes device requests and the device responds to them.
There’s an excellent reason for this host-centric model. The USB architects were keenly mindful of
cost, and the best way to make low-cost peripherals is to put most of the smarts into the host side,
the PC. If USB had been defined as peer-to-peer, every USB device would have required more
intelligence, raising cost.
Here are two important consequences of the “host is master” concept:
1.5.1 Receiving Data from the Host
To send data to a USB peripheral, the host issues an OUT token followed by the data. If the
peripheral has space for the data, and accepts it without error, it returns an ACK to the host. If it is
busy, it instead sends a NAK. If it finds an error, it sends nothing back. For the latter two cases,
the host re-sends the data at a later time.
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1.5.2 Sending Data to the Host
A USB device never spontaneously sends data to the host. Nevertheless, in the EZ-USB chip,
there’s nothing to stop the 8051 from loading data for the host into an endpoint buffer (Section
1.13, "EZ-USB Endpoints") and arming it for transfer. But the data will sit in the buffer until the
host sends an IN token to that particular endpoint. If the host never sends the IN token, the data
sits there indefinitely.
1.6
USB Direction
Once you accept that the host is the bus master, it’s easy to remember USB direction: OUT means
from the host to the device, and IN means from the device to the host. EZ-USB nomenclature
uses this naming convention. For example, an endpoint that sends data to the host is an IN endpoint. This can be confusing at first, because the 8051 sends data by loading an IN endpoint
buffer, but keeping in mind that an 8051 out is IN to the host, it makes sense.
1.7
Frame
The USB host provides a time base to all USB devices by transmitting a SOF (Start Of Frame)
packet every millisecond. The SOF packet includes an incrementing, 11-bit frame count. The
8051 can read this frame count from two EZ-USB registers. SOF-time has significance for isochronous endpoints; it’s the time that the ping-ponging buffers switch places. The EZ-USB core provides the 8051 with an SOF interrupt request for servicing isochronous endpoint data.
1.8
EZ-USB Transfer Types
USB defines four transfer types. These match the requirements of different data types delivered
over the bus. (Section 1.13, "EZ-USB Endpoints" explains how the EZ-USB family supports the
four transfer types.)
1.8.1 Bulk Transfers
A E
I D N
N D D
R P
C
R
C
5
Token Packet
D
A
T
A
1
Payload
Data
Data Packet
C
R
C
1
6
A
C
K
H/S Pkt
A E
O
D N
U
D D
T
R P
C
R
C
5
Token Packet
D
A
T
A
0
Payload
Data
Data Packet
C
R
C
1
6
A
C
K
H/S Pkt
Figure 1-4. Two Bulk Transfers, IN and OUT
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Bulk data is bursty, traveling in packets of 8, 16, 32, or 64 bytes. Bulk data has guaranteed accuracy, due to an automatic re-try mechanism for erroneous data. The host schedules bulk packets
when there is available bus time. Bulk transfers are typically used for printer, scanner, or modem
data. Bulk data has built-in flow control provided by handshake packets.
1.8.2 Interrupt Transfers
A E
I D N
N D D
R P
C
R
C
5
Token Packet
D
A
T
A
1
Payload
Data
C
R
C
1
6
Data Packet
A
C
K
H/S Pkt
Figure 1-5. An Interrupt Transfer
Interrupt data is like bulk data, but exists only for IN endpoints in the “Universal Serial Bus Specification Version 1.1.” Interrupt data can have packet sizes of 1-64 bytes. Interrupt endpoints have
an associated polling interval that ensures that they will be pinged (will receive an IN token) by the
host on a regular basis.
1.8.3 Isochronous Transfers
A E
I D N
N D D
R P
C
R
C
5
Token Packet
D
A
T
A
0
Payload
Data
C
R
C
1
6
Data Packet
Figure 1-6. An Isochronous Transfer
Isochronous data is time-critical and used for streaming data like audio and video. Time of delivery
is the most important requirement for isochronous data. In every USB frame, a certain amount of
USB bandwidth is allocated to isochronous transfers. To lighten the overhead, isochronous transfers have no handshake (ACK/NAK/STALL), and no retries. Error detection is limited to a 16-bit
CRC. Isochronous transfers do not use the data toggle mechanism; isochronous data uses only
the DATA0 PID.
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1.8.4 Control Transfers
S
A E C
E
D N R
T
D D C
U
R P 5
P
Token Packet
A E
I D N
N D D
R P
C
R
C
5
8 bytes
Setup
Data
Data Packet
D
A
T
A
1
Payload
Data
Data Packet
Token Packet
A E
O
D N
U
D D
T
R P
D
A
T
A
0
C
R
C
5
Token Packet
D C
A R
T C
A 1
1 6
Data Pkt
A
C
K
C
R
C
1
6
A
C
K
SETUP
Stage
H/S Pkt
C
R
C
1
6
A
C
K
DATA
Stage
(optional)
H/S Pkt
STATUS
Stage
H/S Pkt
Figure 1-7. A Control Transfer
Control transfers are used to configure and send commands to a device. Being mission critical,
they employ the most extensive error checking USB offers. Control transfers are delivered on a
best effort basis by the host (best effort is defined by a six-step process in the Universal Serial Bus
Specification Version 1.1, “Section 5.5.4”). The host reserves a part of each USB frame time for
Control transfers.
Control transfers consist of two or three stages. The SETUP stage contains eight bytes of USB
CONTROL data. An optional DATA stage contains more data, if required. The STATUS (or handshake) stage allows the device to indicate successful completion of a control operation.
1.9
Enumeration
Your computer is ON. You plug in a USB device, and the Windows cursor switches to an hourglass, and then back to a cursor. And magically, your device is connected and its Windows
driver is loaded! Anyone who has installed a sound card into a PC and had to configure countless
jumpers, drivers, and IO/Interrupt/DMA settings knows that a USB connection can be like a miracle. We’ve all heard about Plug and Play, but USB delivers the real thing.
How does all this happen automatically? Inside every USB device is a table of ‘descriptors’ that
are the sum total of the device’s requirements and capabilities. When you plug into USB, the host
goes through a ‘sign-on’ sequence:
1. The host sends a “Get_Descriptor/Device” request to address zero (devices must respond to
address zero when first attached).
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EZ-USB Technical Reference Manual v1.10
2. The device dutifully responds to this request by sending ID data back to the host telling what it
is.
3. The host sends the device a “Set_Address” request, which gives it a unique address to distinguish it from the other devices connected to the bus.
4. The host sends more “Get_Descriptor” requests, asking more device information. from this, it
learns everything else about the device, like how many endpoints the device has, its power
requirements, what bus bandwidth it requires, and what driver to load.
This sign-on process is called Enumeration.
1.10
The USB Core
A E
O
D N
U
D D
T
R P
C
R
C
5
Token Packet
D
A
T
A
1
Payload
Data
Data Packet
C
R
C
1
6
A
C
K
H/S Pkt
A E
O
D N
U
D D
T
R P
C
R
C
5
D
A
T
A
0
Token Packet
Payload
Data
Data Packet
C
R
C
1
6
A
C
K
H/S Pkt
Payload
Data
Serial
Interface
Engine
(SIE)
D+
D-
USB
Tranceiver
Payload
Data
A
C
K
Figure 1-8. What the SIE Does
Every USB device has a Serial Interface Engine (SIE). The SIE connects to the USB data lines D+
and D-, and delivers bytes to and from the USB device. Figure 1-8 illustrates a USB bulk transfer,
with time moving from left to right. The SIE decodes the packet PIDs, performs error checking on
the data using the transmitted CRC bits, and delivers payload data to the USB device. If the SIE
encounters an error in the data, it automatically indicates no response instead of supplying a handshake PID. This instructs the host to re-transmit the data at a later time.
Bulk transfers such as the one illustrated in Figure 1-8 are asynchronous, meaning that they
include a flow control mechanism using ACK and NAK handshake PIDs. The SIE indicates busy
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to the host by sending a NAK handshake packet. When the peripheral device has successfully
transferred the data, it commands the SIE to send an ACK handshake packet, indicating success.
To send data to the host, the SIE accepts bytes and control signals from the USB device, formats
it for USB transfer, and sends it over the two-wire USB. Because the USB uses a self-clocking
data format (NRZI), the SIE also inserts bits at appropriate places in the bit stream to guarantee a
certain number of transitions in the serial data. This is called “bit stuffing,” and is transparently
handled by the SIE.
One of the most important features of the EZ-USB family is that it is soft. Instead of requiring
ROM or other fixed memory, it contains internal program/data RAM that is downloaded over the
USB itself to give the device its unique personality. This make modifications, specification revisions, and updates a snap.
The EZ-USB family can connect as a USB device and download code into internal RAM, all while
its internal 8051 is held in RESET. This is done by an enhanced SIE, which does all of the work
shown in Figure 1-8, and more. It contains additional logic to perform a full enumeration, using an
internal table of descriptors. It also responds to a vendor specific “Firmware Download” device
request to load its internal RAM. An added bonus is that the added SIE functionality is also made
available to the 8051. This saves 8051 code and processing time.
Throughout this manual, the SIE and its enhancements are referred to as the “USB Core.”
1.11
EZ-USB Microprocessor
The EZ-USB microprocessor is an enhanced 8051 core. Use of an 8051 compatible processor
makes extensive software support tools immediately available to the EZ-USB designer. This
enhanced 8051 core, described in Chapter 2, "EZ-USB CPU" and Appendices A-C, has the following features:
•
4-clock cycle, as compared to the 12-clock cycle of a standard 8051, giving a 3X speed
improvement.
•
Dual data pointers for faster memory-to-memory transfers.
•
Two UARTs.
•
Three counter-timers.
•
An expanded interrupt system.
•
24-MHz clock.
•
256 bytes of internal register RAM.
•
Standard 8051 instruction set—if you know the 8051, you know EZ-USB
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The enhanced 8051 core uses on-chip RAM as program and data memory, giving EZ-USB its soft
feature. Chapter 3, "EZ-USB Memory" describes the various memory options.
The 8051 communicates with the SIE using a set of registers, which occupy the top of the on-chip
RAM address space. These registers are grouped and described by function in individual chapters
of this reference manual, and summarized in register order in Chapter 12, "EZ-USB Registers."
The EZ-USB 8051 has two duties. First, it participates in the protocol defined in the Universal
Serial Bus Specification Version 1.1, “Chapter 9, USB Device Framework.” Thanks to EZ-USB
enhancements to the SIE and USB interface, the 8051 firmware associated with USB overhead is
simplified, leaving code space and bandwidth available for the 8051’s primary duty, to help implement your device. On the device side, abundant input/output resources are available, including IO
ports, UARTs, and an I2C bus master controller. These resources are described in Chapter 4, "EZUSB Input/Output."
1.12
ReNumeration™
Because it is soft, the EZ-USB chip can take on the identities of multiple distinct USB devices. The
first device downloads your 8051 firmware and USB descriptor tables over the USB cable when
the peripheral device is plugged in. Once downloaded, another device comes on as a totally different USB peripheral as defined by the downloaded information. This two-step process, called
ReNumeration™ , happens instantly when the device is plugged in, with no hint that the initial load
step has occurred.
Chapter 5, "EZ-USB Enumeration and ReNumeration™" describes this feature in detail, along with
other EZ-USB boot (startup) modes.
1.13
EZ-USB Endpoints
The Universal Serial Bus Specification Version 1.1 defines an endpoint as a source or sink of data.
Since USB is a serial bus, a device endpoint is actually a FIFO which sequentially empties/fills with
USB bytes. The host selects a device endpoint by sending a 4-bit address and one direction bit.
Therefore, USB can uniquely address 32 endpoints, IN0 through IN15 and OUT0 through OUT15.
From the EZ-USB point of view, an endpoint is a buffer full of bytes received or to be transmitted
over the bus. The 8051 reads endpoint data from an OUT buffer, and writes endpoint data for
transmission over USB to an IN buffer.
Four USB endpoint types are defined as: Bulk, Control, Interrupt, and Isochronous.
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1.13.1 EZ-USB Bulk Endpoints
Bulk endpoints are unidirectional—one endpoint address per direction. Therefore endpoint 2-IN is
addressed differently than endpoint 2-OUT. Bulk endpoints use maximum packet sizes (and
therefore buffer sizes) of 8, 16, 32, or 64 bytes. EZ-USB provides fourteen bulk endpoints, divided
into seven IN endpoints (endpoint 1-IN through 7-IN), and seven OUT endpoints (endpoint 1-OUT
through 7-OUT). Each of the fourteen endpoints has a 64-byte buffer.
Bulk data is available to the 8051 in RAM form, or as FIFO data using a special EZ-USB Autopointer (Chapter 6, "EZ-USB Bulk Transfers").
1.13.2 EZ-USB Control Endpoint Zero
Control endpoints transfer mission-critical control information to and from the USB device. The
Universal Serial Bus Specification Version 1.1 requires every USB device to have a default CONTROL endpoint, endpoint zero. Device enumeration, the process that the host initiates when the
device is first plugged in, is conducted over endpoint zero. The host sends all USB requests over
endpoint zero.
Control endpoints are bi-directional; if you have an endpoint 0 IN CONTROL endpoint, you automatically have an endpoint 0 OUT endpoint. Control endpoints alone accept SETUP PIDs.
A CONTROL transfer consists of a two or three stage sequence:
•
SETUP
•
DATA (If needed)
•
HANDSHAKE
Eight bytes of data in the SETUP portion of the CONTROL transfer have special USB significance,
as defined in the Universal Serial Bus Specification Version 1.1, “Chapter 9.” A USB device must
respond properly to the requests described in this chapter to pass USB compliance testing (usually referred to as the USB “Chapter Nine Test”).
Endpoint zero is the only CONTROL endpoint in the EZ-USB chip. The 8051 responds to device
requests issued by the host over endpoint zero. The EZ-USB core is significantly enhanced to
simplify the 8051 code required to service these requests. Chapter 7, "EZ-USB Endpoint Zero"
provides a detailed roadmap for writing USB Chapter 9 compliant 8051 code.
1.13.3 EZ-USB Interrupt Endpoints
Interrupt endpoints are almost identical to bulk endpoints. Fourteen EZ-USB endpoints (EP1-EP7,
IN, and OUT) may be used as interrupt endpoints. Interrupt endpoints have maximum packet
sizes up to 64, and contain a “polling interval” byte in their descriptor to tell the host how often to
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service them. The 8051 transfers data over interrupt endpoints in exactly the same way as for bulk
endpoints. Interrupt endpoints are described in Chapter 6, "EZ-USB Bulk Transfers."
1.13.4 EZ-USB Isochronous Endpoints
Isochronous endpoints deliver high bandwidth, time critical data over USB. Isochronous endpoints
are used to stream data to devices such as audio DACs, and from devices such as cameras and
scanners. Time of delivery is the most critical requirement, and isochronous endpoints are tailored
to this requirement. Once a device has been granted an isochronous bandwidth slot by the host, it
is guaranteed to be able to send or receive its data every frame.
EZ-USB contains 16 isochronous endpoints, numbered 8-15 (8IN-15IN, and 8OUT-15OUT).
1,024 bytes of FIFO memory are available to the 16 endpoints, and may be FIFO memory to provide double-buffering. Using double buffering, the 8051 reads OUT data from isochronous endpoint FIFOs containing data from the previous frame while the host writes current frame data into
the other buffer. Similarly, the 8051 loads IN data into isochronous endpoint FIFOs that will be
transmitted over USB during the next frame while the host reads current frame data from the other
buffer. At every SOF the USB FIFOs and 8051 FIFOs switch, or ping-pong.
Isochronous transfers are described in Chapter 8, "EZ-USB Isochronous Transfers."
1.14
Fast Transfer Modes
The following versions of the EZ-USB have a fast transfer mode: AN2135SC, AN2136SC, and
AN2131QC, that is, those versions that have a data bus (see Table 1-2). The fast transfer mode
minimizes the transfer time from EZ-USB core also supplies external FIFO read and write strobes
to synchronize the transfers.
Using the fast transfer mode, the 8051 transfers a byte of data between an internal FIFO and the
external bus using a single 8051 MOVX instruction, which takes two cycles or 333 ns. Both Isochronous and Bulk endpoints can use this fast transfer mode.
1.15
Interrupts
The EZ-USB enhanced 8051 adds seven interrupt sources to the standard 8051 interrupt system.
Three of the added interrupts are used internally, and the others are available on device pins.
INT2 is used for all USB interrupts. INT3 is used by the I2C interface. A third interrupt is used for
remote wakeup indication.
The EZ-USB core automatically supplies jump vectors (Autovectors) for its USB interrupts to save
the 8051 from having to test bits to determine the source of the interrupt. Each BULK/CONTROL/
INTERRUPT endpoint has its own vector, so when an endpoint requires service, the proper interrupt service routine is automatically invoked. The 8051 services all isochronous endpoints in
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response to a SOF (Start Of Frame) interrupt request. Chapter 9, "EZ-USB Interrupts" describes
the EZ-USB interrupt system.
1.16
Reset and Power Management
The EZ-USB chip contains four resets:
•
Power-On-Reset (POR)
•
USB bus reset
•
8051 reset
•
USB Disconnect/Re-connect
The functions of the various EZ-USB resets are described in Chapter 10, "EZ-USB Resets."
A USB peripheral may be put into a low power state when the host signals a suspend operation.
The Universal Serial Bus Specification Version 1.1 states that a bus powered device cannot draw
more than 500 uA of current from the Vcc wire while in suspend. The EZ-USB chip contains logic
to turn off its internal oscillator and enter a sleep state. A special interrupt, triggered by a wakeup
pin or wakeup signaling on the USB bus, starts the oscillator and interrupts the 8051 to resume
operation.
Low power operation is described in Chapter 11, "EZ-USB Power Management."
Page 1-14
EZ-USB Technical Reference Manual v1.10
1.17
EZ-USB Product Family
The EZ-USB family is available in various pinouts to serve different system requirements and
costs. Table 1-2 shows the feature set for each member of the EZ-USB Series 2100 Family.
Table 1-2. EZ-USB Series 2100 Family
Key Features
Part
RAM ISO
Number Size Support
AN2131Q 8KB
Endpoints
Y
32
Data Bus I/O Rate Prog
or Port B Bytes/s Max I/Os
Package
Both
2M
24 Q = 80 PQFP
Max UART Power
(Async) Saving IBN/
Speed
Option STOP
(Kbaud)
115.2
N
N
AN2131S 8KB
Y
32
Port B
600K
18 S = 44 PQFP
115.2
N
N
AN2135S 8KB
Y
32
Data Bus
2M
8
S = 44 PQFP
115.2
N
N
AN2136S 8KB
N
16
Data Bus
2M
8
S = 44 PQFP
115.2
N
N
1.18
Pin Descriptions
Figures 1-9 through 1-11 are pin descriptions by package type. Table 1-3 describes the pins by pin
function.
Chapter 1. Introducing EZ-USB
Page 1-15
PC7/RD#
VCC
GND
PB1/T2EX
PB0/T2
PB2/RxD1
PB3/TxD1
D0
D1
D2
D3
PB4/INT4
PB5/INT5#
PB6/INT6
PB7/T2out
GND
D4
D5
D6
BKPT
D7
VCC
SDA
GND
EZ-USB Technical Reference Manual
64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 48 47 46 45 44 43 42 41
SCL
65
40
PC6/WR#
WAKEUP#
66
39
PC5/T1
NC
67
38
PC4/T0
PA0/T0out
68
37
A15
PA1/T1out
69
36
A14
PA2/OE#
70
35
A13
PA3/CS#
71
34
A12
GND
72
33
PC3/INT1#
PA4/FWR#
73
32
PC2/INT0#
PA5/FRD#
74
31
PC1/TxD0
PA6/RXD0out
75
30
PC0/RxD0
PA7/RXD1out
76
29
A11
USBD-
77
28
A10
GND
78
27
A9
USBD+
79
26
A8
PSEN#
80
25
RESET
EA
VCC
GND
AVCC
XOUT
XIN
A2
AGND
A1
GND
A0
A7
GND
A6
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
GND
8
GND
7
A5
6
A4
5
A3
4
GND
VCC
3
GND
2
CLK24
1
DISCON#
80 PQFP
14 x 20 mm
Figure 1-9. 80-pin PQFP Package (AN2131Q)
Page 1-16
EZ-USB Technical Reference Manual v1.10
VCC
DISCON#
USBD+
USBD-
PA5/FRD#
PA4/FWR#
GND
WAKEUP#
SCL
SDA
GND
44
43
42
41
40
39
38
37
36
35
34
GND
1
33
VCC
CLK24
2
32
BKPT
GND
3
31
PB7/T2OUT
GND
4
30
PB6/INT6
GND
5
29
PB5/INT5#
GND
6
28
PB4/INT4
AGND
7
27
PB3/TxD2
XIN
8
26
PB2/RxD2
XOUT
9
25
PB1/T2EX
AVCC
10
24
PB0/T2
VCC
11
23
GND
12
13
14
15
16
17
18
19
20
21
22
GND
RESET
PC0/RxD0
PC1/TxD0
PC2/INT0#
PC3/INT1#
PC4/T0
PC5/T1
PC6/WR#
PC7/RD#
VCC
44 PQFP
10 x 10 mm
Figure 1-10. 44-pin PQFP Package with Port B (AN2131S)
Chapter 1. Introducing EZ-USB
Page 1-17
VCC
DISCON#
USBD+
USBD-
PA5/FRD#
PA4/FWR#
GND
WAKEUP#
SCL
SDA
GND
EZ-USB Technical Reference Manual
44
43
42
41
40
39
38
37
36
35
34
GND
1
33
VCC
CLK24
2
32
BKPT
GND
3
31
D7
GND
4
30
D6
GND
5
29
D5
GND
6
28
D4
AGND
7
27
D3
XIN
8
26
D2
XOUT
9
25
D1
AVCC
10
24
D0
VCC
11
23
GND
14
15
16
17
18
19
20
RESET
PC0/RxD0
PC1/TxD0
PC2/INT0#
PC3/INT1#
PC4/T0
PC5/T1
PC6/WR#
21
22
VCC
13
PC7/RD#
12
GND
44 PQFP
10 x 10 mm
Figure 1-11. 44-pin Package with Data Bus (AN2135, and AN2136)
Page 1-18
EZ-USB Technical Reference Manual v1.10
Table 1-3. EZ-USB Series 2100 Pinouts by Pin Function
2125S
2121S
2126S
2131Q 2122S
2122T 2126T
2135S
2131S
2136S
Name
Type Default
Description
21
10
10
11
11
AVCC
Power
N/A
Analog Vcc. This signal provides power to
the analog section of the chip.
18
7
7
7
7
AGND
Power
N/A
Analog Ground. Connect to ground with as
short a path as possible.
1
43
43
47
47
DISCON#
Output
HI
Disconnect. This pin is controlled by two bits,
DISCOE and DISCON. When
DISCOE=0, the pin floats. When DISCOE=1,
it drives. When DISCOE=1, the driven logic
level is the inverse of the DISCON bit.
77
41
41
45
45
USBD
I/O/Z
Z
USB D- signal. Connect to the USB D- signal
through a 24-ohm resistor.
79
42
42
46
46
USBD
I/O/Z
Z
USB D+ signal. Connect to the USB D+ pin
through a 24-ohm resistor.
7-12, N/A
15, 16,
26-29,
34-37
N/A
N/A
N/A
A0-A5, A6, Output 0x0000 8051 Address bus. This bus is driven at all
A7, A8-A11,
times. When the 8051 is addressing internal
A12-A15
RAM it reflects the internal address.
48-51, N/A
57-60
24-27, N/A
28-31
26-29, D0-D3,
30-33 D4-D7
80
N/A
N/A
N/A
N/A
61
32
32
35
25
13
13
14
Chapter 1. Introducing EZ-USB
I/O/Z
Z
8051 Data bus. This bi-directional bus is
high-impedance when inactive, input for bus
reads, and output for bus writes. The data bus
is also used to transfer data directly to and
from internal EZ-USB FIFOs under control of
the FRD# and FWR# strobes. D0-D7 are
active only for external bus accesses, and are
driven low in suspend.
PSEN#
Output
H
Program Store Enable. This active-low signal indicates a code fetch from external memory. It is active for program memory fetches
above 0x1B40 when the EA pin is LO, or
above 0x0000 when the EA pin is HI.
35
BKPT
Output
0
Breakpoint. This pin goes active (high) when
the 8051 address bus matches the BPADDRH/L registers and breakpoints are enabled
in the USBBAV register (BPEN=1). If the
BPPULSE bit in the USBBAV register is HI,
this signal pulses high for eight 24-MHz
clocks. If the BPPULSE bit is LO, the signal
remains high until the 8051 clears the BREAK
bit (by writing 1 to it) in the USBBAV register.
14
RESET
Input
N/A
Active High Reset. Resets the 8051 and the
USB SIE. This pin is normally tied to ground
through a 10K-ohm resistor and to Vcc
through a 1 mF capacitor.
Page 1-19
EZ-USB Technical Reference Manual
Table 1-3. EZ-USB Series 2100 Pinouts by Pin Function (Continued)
2125S
2121S
2126S
2131Q 2122S
2122T 2126T
2135S
2131S
2136S
Name
Type Default
Description
24
N/A
N/A
N/A
N/A
EA
Input
N/A
External Access. If this signal is active
(high), the 8051 fetches code from external
memory instead of the internal program RAM.
If EA=0, the 8051 fetches code from external
memory starting at 0x1B40 (AN2131).
19
8
8
9
9
XIN
Input
N/A
Crystal Input. Connect this signal to a 12MHz series resonant, fundamental mode crystal and 22-33-pF capacitor to GND. This pin
may also be driven by a 12-MHz clock.
20
9
9
10
10
XOUT
Output
N/A
Crystal Output. Connect this signal to a 12MHz series resonant, fundamental mode crystal and 22-33-pF capacitor to GND. If XIN is
driven by a 12-MHz clock, this pin should not
be connected.
68
N/A
N/A
34
34
PA0 or
T0OUT
I/O
I
Multiplexed pin whose function is selected by
(PA0) the T0OUT bit of the PORTACFG register. If
T0OUT=0, the pin is the bi-directional I/O port
bit PA0. If T0OUT=1, the pin is the active-high
T0OUT signal from 8051 Timer/Counter0.
T0OUT outputs a high level for one CLK24
clock cycle when Timer0 overflows. If Timer0
is operated in mode 3 (two separate timer/
counters), T0OUT is active when the low byte
timer/counter overflows.
69
N/A
N/A
N/A
N/A
PA1 or
T1OUT
I/O
I
Multiplexed pin whose function is selected by
(PA1) the T1OUT bit of the PORTACFG register. If
T1OUT=0, the pin is the bi-directional I/O port
bit PA1. If T1OUT=1, the pin is the active-high
T1OUT signal from 8051 Timer-counter1.
T1OUT outputs a high level for one CLK24
clock cycle when Timer1 overflows. If Timer1
is operated in mode 3 (two separate timer/
counters), T1OUT is active when the low byte
timer/counter overflows.
70
N/A
Page 1-20
N/A
N/A
N/A
PA2 or OE#
I/O
I
Multiplexed pin whose function is selected by
(PA2) the OE bit of the PORTACFG register. If
OE=0, the pin is the bi-directional I/O port pin
PA2. If OE=1, the pin is an active-low output
enable for external memory. If the OE# pin is
used, it should be externally pulled up to Vcc
to ensure that the write strobe is inactive
(high) at power-on.
EZ-USB Technical Reference Manual v1.10
Table 1-3. EZ-USB Series 2100 Pinouts by Pin Function (Continued)
2125S
2121S
2126S
2131Q 2122S
2122T 2126T
2135S
2131S
2136S
Name
Type Default
Description
71
N/A
N/A
N/A
N/A
PA3 or CS#
I/O
I
Multiplexed pin whose function is selected by
(PA3) the CS bit of the PORTACFG register. If
CS=0, the pin is the bi-directional I/O port pin
PA3. If CS=1, the pin is an active-low chip
select for external memory. If the CS# pin is
used, it should be externally pulled up to Vcc
to ensure that the write strobe is inactive
(high) at power-on.
73
39
39
N/A
N/A
PA4 or
FWR#
I/O
I
Multiplexed pin whose function is selected by
(PA4) the FWR (Fast Write) bit of the PORTAFCG
register. If FWR=0, the pin is the bi-directional
I/O port pin PA4. If FWR=1, the pin is the
write strobe for an external FIFO. If the FWR#
pin is used, it should be externally pulled up to
Vcc to ensure that the write strobe is inactive
(high) at power-on.
74
40
40
N/A
N/A
PA5 or
FRD#
I/O
I
Multiplexed pin whose function is selected by
(PA5) the FRD (Fast Read) bit of the PORTAFCG
register. If FRD=0, the pin is the bi-directional
I/O port pin PA5. If FRD=1, the pin is the read
strobe for an external FIFO. If the FRD# pin is
used, it should be externally pulled up to Vcc
to ensure that the write strobe is inactive
(high) at power-on.
75
N/A
N/A
44
44
PA6 or
RXD0OUT
I/O
I
Multiplexed pin whose function is selected by
(PA6) the RXD0OUT bit of the PORTAFCG register. If RXD0OUT=0 (default), the pin is the bidirectional I/O port bit PA6. If RXD0OUT=1,
the pin is the active-high RXD0OUT signal
from 8051 UART0.
If RXD0OUT is selected and UART0 is in
mode 0, this pin provides the output data for
UART0 only when it is in sync mode. Otherwise, it is a 1.
76
N/A
N/A
8
8
PA7 OR
RXD1OUT
I/O
I
Multiplexed pin whose function is selected by
(PA7) the RXD1OUT bit of the PORTAFCG register. If RXD1OUT=0 (default), the pin is the bidirectional I/O port bit PA7. If RXD1OUT=1,
the pin is the active-high RXD1OUT signal
from 8051 UART1.
When RXD1OUT is selected and UART1 is in
mode 0, this pin provides the output data for
UaRT1 only when it is in sync mode. In
modes 1, 2, and 3, this pin is a 1.
Chapter 1. Introducing EZ-USB
Page 1-21
EZ-USB Technical Reference Manual
Table 1-3. EZ-USB Series 2100 Pinouts by Pin Function (Continued)
2125S
2121S
2126S
2131Q 2122S
2122T 2126T
2135S
2131S
2136S
Name
Type Default
Description
44
24
N/A
26
N/A
PB0 or T2
I/O
I
Multiplexed pin whose function is selected by
(PB0) the T2 bit of the PORTBFCG register. If T2=0,
the pin is the bi-directional I/O port bit PB0. If
T2=1, the pin is the active-high T2 signal from
8051 Timer2, which provides the input to
Timer2 when C/T2=1. When C/T2=0, Timer2
does not use this pin.
45
25
N/A
27
N/A
PB1 or
T2EX
I/O
I
Multiplexed pin whose function is selected by
(PB1) the T2EX bit of the PORTBCFG register. If
T2EX=0, the pin is the bi-directional I/O port
bit PB1. If T2EX=1, the pin is the active-high
T2EX signal from 8051 Timer2.
46
26
N/A
28
N/A
PB2 or
RXD1
I/O
I
Multiplexed pin whose function is selected by
(P{B2) the RXD1 bit of the PORTBCFG register. If
RXD1=0, the pin is the bi-directional I/O port
bit PB2. If RXD1=1, the pin is the active-high
RXD1 input signal for 8051 UART1, which
provides data to the UART in all modes.
47
27
N/A
29
N/A
PB3 or
TXD1
I/O
I
Multiplexed pin whose function is selected by
(PB3) the TXD1 bit of the PORTBCFG register. If
TXD1=0, the pin is the bi-directional I/O port
bit PB3. If TXD1=1, the pin is the active-high
TXD1 output pin for 8051 UART1 which provides the output clock in sync mode and the
output data in async mode.
52
28
N/A
30
N/A
PB4 or INT4
I/O
I
Multiplexed pin whose function is selected by
(PB4) the INT4 bit of the PORTBCFG register. If
INT4=0, the pin is the bi-directional I/O port bit
PB4. If INT4=1, the pin is the 8051 INT4 interrupt request signal. The INT4 pin is edge-sensitive, active high.
53
29
N/A
31
N/A
PB5 or
INT5#
I/O
I
Multiplexed pin whose function is selected by
(PB5) the INT5 bit of the PORTBCFG register. If
INT5=0, the pin is the bi-directional I/O port bit
PB5. If INT5=1, the pin is the INT5# interrupt
register signal. The INT5# pin is edge-sensitive, active low.
54
30
N/A
32
N/A
PB6 or INT6
I/O
I
Multiplexed pin whose function is selected by
(PB6) the INT6 bit of the PORTBCFG register. If
INT6=0, the pin is the bi-directional I/O port bit
PB6. If INT6=1, the pin is the INT6 interrupt
request signal. The INT6 pin is edge-sensitive, active high.
Page 1-22
EZ-USB Technical Reference Manual v1.10
Table 1-3. EZ-USB Series 2100 Pinouts by Pin Function (Continued)
2125S
2121S
2126S
2131Q 2122S
2122T 2126T
2135S
2131S
2136S
55
31
N/A
33
N/A
Name
PB7 or
T2OUT
Type Default
I/O
Description
I
Multiplexed pin whose function is selected by
(PB7) the T2OUT bit of the PORTBCFG register. If
T2OUT=0, the pin is the bi-directional I/O port
bit PB7. If T2OUT=1, the pin is the active-high
T2OUT signal from 8051 Timer2.
T2OUT is active (high) for one clock cycle
when Timer/Counter 2 overflows.
30
14
14
16
16
PC0 or
RXD0
I/O
I
Multiplexed pin whose function is selected by
(PC0) the RXD0 bit of the PORTCCFG register. If
RXD0=0, the pin is the bi-directional I/O port
bit PC0. If RXD0=1, the pin is the active-high
RXD0 from 8051 UART0, which provides data
to the UART in all modes.
31
15
15
17
17
PC1 or
TXD0
I/O
I
Multiplexed pin whose function is selected by
(PC1) the TXD0 bit of the PORTCCFG register. If
TXD0=0, the pin is the bi-directional I/O port
bit PC1. If TXD0=1, the pin is the active-high
TXD0 signal for 8051 UART0, which provides
the output clock in sync mode, and the output
data in async mode.
32
16
16
18
18
PC2 or
INT0#
I/O
I
Multiplexed pin whose function is selected by
(PC2) the INT0 bit of the PORTCCFG register. If
INT0=0, the pin is the bi-directional I/O port bit
PC2. If INT0=1, the pin is the active-low 8051
INT0 interrupt input signal, which is either
edge triggered (IT0=1) or level triggered
(IT0=0).
33
17
17
19
19
PC3 or
INT1#
I/O
I
Multiplexed pin whose function is selected by
(PC3) the INT1 bit of the PORTCCFG register. If
INT1=0, the pin is the bi-directional I/O port bit
PC3. If INT1=1, the pin is the active-low 8051
INT1 interrupt input signal, which is either
edge triggered (IT1=1) or level triggered
(IT1=0).
38
18
18
20
20
PC4 or T0
I/O
I
Multiplexed pin whose function is selected by
(PC4) the T0 bit of the PORTCCFG register. If T0=0,
the pin is the bi-directional I/O port bit PC4. If
T0=1, the pin is the active-high T0 signal for
8051 Timer0, which provides the input to
Timer0 when C/T0 is 1. When C/T0 is 0,
Timer0 does not use this bit.
Chapter 1. Introducing EZ-USB
Page 1-23
EZ-USB Technical Reference Manual
Table 1-3. EZ-USB Series 2100 Pinouts by Pin Function (Continued)
2125S
2121S
2126S
2131Q 2122S
2122T 2126T
2135S
2131S
2136S
Name
Type Default
Description
39
19
19
21
21
PC5 or T1
I/O
I
Multiplexed pin whose function is selected by
(PC5) the T1 bit of the PORTCCFG register. If T1=0,
the pin is the bi-directional I/O port bit PC5. If
T1=1, the pin is the active-high T1 signal from
8051 Timer1, which provides the input to
Timer1 when C/T1 is 1. When C/T0 is 0,
Timer1 does not use this bit.
40
20
20
22
22
PC6 or WR#
I/O
I
Multiplexed pin whose function is selected by
(PC6) the WR bit of the PORTCCFG register. If
WR=0, the pin is the bi-directional I/O port bit
PC6. If WR=1, the pin is the active-low write
signal for external memory. If the WR# signal
is used, it should be externally pulled up to
Vcc to ensure that the write strobe is inactive
at power-on.
41
21
21
23
23
PC7 or RD#
I/O
I
Multiplexed pin whose function is selected by
(PC7) the RD bit of the PORTCCFG register. If
RD#=0, the pin is the bi-directional I/O port bit
PC7. If RD#=1, the pin is the active-low read
signal for external memory. If the RD# signal
is used, it should be externally pulled up to
Vcc to ensure that the read strobe is inactive
at power-on.
4
2
2
2
2
CLK24
66
37
37
40
40
WAKEUP#
65
36
36
39
39
64
35
35
38
38
24-MHz clock, phase locked to the 12-MHz
input clock. It operates at 12 MHz in 12-MHz
mode (48-pin package). Output is disabled by
setting the OUTCLKEN bit = 0 in the CPUCS
register.
Input
N/A
SCL
OD
Z
I2C Clock. Pull up to Vcc with a 2.2K-ohm
resistor, even if no I2C device is connected.
SDA
OD
Z
I2C Data. Connect to Vcc with a 2.2K-ohm
resistor even if no I2C device is connected.
2, 22, 11, 22, 11, 22, 12, 24, 12, 24, Vcc
42, 62 33, 44 33, 44 36, 48 36, 48
Page 1-24
Output
N/A
USB Wakeup. If the 8051 is in suspend, a
high to low edge on this pin starts up the oscillator and interrupts the 8051 to allow it to exit
the suspend mode. Holding WAKEUP# LOW
inhibits the EZ-USB chip from entering the
suspend state.
Vcc. 3.3V power source.
EZ-USB Technical Reference Manual v1.10
Table 1-3. EZ-USB Series 2100 Pinouts by Pin Function (Continued)
2125S
2121S
2126S
2131Q 2122S
2122T 2126T
2135S
2131S
2136S
3, 5, 6,
13, 14,
17, 23,
43, 56,
63, 72,
78
1, 3, 4,
5, 6,
12, 23,
34, 38
1, 3, 4,
5, 6,
12, 23,
34, 38
1, 3, 4,
5, 6,
13, 25,
37, 41
Name
1, 3, 4, GND
5, 6,
13, 25,
37, 41
Type Default
N/A
Description
Ground. Note: On the 80-pin package, pins 5,
6, 13, 14, and 72 are test pins that must be
grounded for normal operation. Driving pin 72
high floats all functional pins for automated
board test.
The corresponding pins on the 44-pin package are pins 3, 4, 5, 6, and 38. Driving pin 38
high floats all functional pins for automated
board test.
The corresponding pins on the 48-pin package are pins 3, 4, 5, 6, and 41. Driving pin 41
high floats all functional pins for automated
board testing.
N/A
N/A
N/A
15
15
CPU12MHZ
N/A
This input controls the speed of the 8051:
- Tied High - 12 MHz
- Tied Low - 24 MHz
67
N/A
N/A
N/A
N/A
NC
N/A
This pin must be left unconnected.
Chapter 1. Introducing EZ-USB
Page 1-25
EZ-USB Technical Reference Manual
Page 1-26
EZ-USB Technical Reference Manual v1.10
Chapter 2
2.1
EZ-USB CPU
Introduction
The EZ-USB built-in microprocessor, an enhanced 8051 core, is fully described in Appendices AC. This chapter introduces the processor, its interface to the EZ-USB core, and describes architectural differences from a standard 8051.
2.2
8051 Enhancements
The enhanced 8051 core uses the standard 8051 instruction set. Instructions execute faster than
with the standard 8051 due to two features:
•
Wasted bus cycles are eliminated. A bus cycle uses four clocks, as compared to 12 clocks
with the standard 8051.
•
The 8051 runs at 24 MHz.
In addition to the speed improvement, the enhanced 8051 core also includes architectural
enhancements:
1. A second data pointer.
2. A second UART.
3. A third, 16-bit timer (TIMER2).
4. A high-speed memory interface with a non-multiplexed 16-bit address bus.
5. Eight additional interrupts (INT2-INT5, PFI, T2, and UART1).
6. Variable MOVX timing to accommodate fast/slow RAM peripherals.
7. 3.3V operation.
Chapter 2. EZ-USB CPU
Page 2-1
EZ-USB Technical Reference Manual
2.3
EZ-USB Enhancements
The EZ-USB chip provides additional enhancements outside the 8051. These include:
•
Fast external transfers (Autopointer, Fast Transfer Mode)
•
Vectored USB interrupts (Autovector)
•
Separate buffers for SETUP and DATA portions of a CONTROL transfer.
•
Breakpoint Facility.
2.4
EZ-USB Register Interface
The 8051 communicates with the EZ-USB core through a set of memory mapped registers.
These registers are grouped as follows:
•
Endpoint buffers and FIFOs
•
8051 control
•
IO ports
•
Fast Transfer
•
I2C Controller
•
Interrupts
•
USB Functions
These registers and their functions are described throughout this manual. A full description of
every register and bit appears in Chapter 12, “EZ-USB Registers.”
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EZ-USB Technical Reference Manual v1.10
2.5
EZ-USB Internal RAM
FF
80
7F
00
Upper 128
bytes
Indirect Addr
SFR Space
Direct Addr
Lower 128
bytes
Direct Addr
Figure 2-1. 8051 Registers
Like the standard 8051, the EZ-USB 8051 core contains 128 bytes of register RAM at 00-7F, and a
partially populated SFR register space at 80-FF. An additional 128 indirectly addressed registers
(sometimes called “IDATA”) are also available at 80-FF.
All internal EZ-USB RAM, which includes program/data memory, bulk endpoint buffer memory, and
the EZ-USB register set, is addressed as add-on 8051 memory. The 8051 reads or writes these
bytes as data using the MOVX (move external) instruction. Even though the MOVX instruction
implies external memory, the EZ-USB RAM and register set is actually inside the EZ-USB chip.
External memory attached to the AN2131Q address and data busses can also be accessed by the
MOVX instruction. The EZ-USB core encodes its memory strobe and select signals (RD#, WR#,
CS#, and OE#) to eliminate the need for external logic to separate the internal and external memory spaces.
2.6
I/O Ports
A standard 8051 communicates with its IO ports 0-3 through four Special Function Registers
(SFRs). Standard 8051 IO pins are quasi-bidirectional with weak pullups that briefly drive high
only when the pin makes a zero-to-one transition.
The EZ-USB core implements IO ports differently than a standard 8051, as described in
Chapter 4, "EZ-USB Input/Output." Instead of using the 8051 IO ports and SFRs, the EZ-USB
core implements a flexible IO system that is controlled via EZ-USB register set. Each EZ-USB IO
pin functions identically, having the following resources:
•
An output latch. Used when the pin is an output port.
•
A bit that indicates the state of the IO pin, regardless of its configuration (input or output).
•
An output enable bit that causes the IO pin to be driven from the output latch.
Chapter 2. EZ-USB CPU
Page 2-3
EZ-USB Technical Reference Manual
•
An alternate function bit that determines whether the pin is general IO or a special 8051 or
EZ-USB function.
The SFRs associated with 8051 ports 0-3 are not implemented in EZ-USB. These SFR addresses
include P0 (0x80), P1 (0x90), P2 (0xA0), and P3 (0xB0). Because P2 is not implemented, the
MOVX@R0/R1 instruction takes the upper address byte from an added Special Function Register
(SFR) at location 0x92. This register is called “MPAGE” in the Appendices.
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EZ-USB Technical Reference Manual v1.10
2.7
Interrupts
All standard 8051 interrupts are supported in the enhanced 8051 core. Table 2-1 shows the existing and added 8051 interrupts, and indicates how the added ones are used.
Table 2-1. EZ-USB Interrupts
Standard 8051
Interrupts
Enhanced 8051
Interrupts
Used As
INT0
Device Pin INT0#
INT1
Device Pin INT1#
Timer 0
Internal, Timer 0
Timer 1
Internal, Timer 1
Tx0 & Rx0
Internal, UART0
INT2
Internal, USB
INT3
Internal, I2C Controller
INT4
Device Pin, PB4/INT4
INT5
Device Pin, PB5/INT5#
INT6
Device Pin, PB6/INT6
PF1
Device Pin, USB WAKEUP#
Tx1 & Rx1
Internal, UART1
Timer 2
Internal, Timer 2
The EZ-USB chip uses 8051 INT2 for 21 different USB interrupts: 16 bulk endpoints plus SOF,
Suspend, SETUP Data, SETUP Token, and USB Bus Reset. To help the 8051 determine which
interrupt is active, the EZ-USB core provides a feature called Autovectoring. The core inserts an
address byte into the low byte of the 3-byte jump instruction found at the 8051 INT2 vector
address. This second level of vectoring automatically transfers control to the appropriate USB
ISR. The Autovector mechanism, as well as the EZ-USB interrupt system is the subject of Chapter
9, "EZ-USB Interrupts."
2.8
Power Control
The EZ-USB core implements a power-down mode that allows it to be used in USB bus powered
devices that must draw no more than 500 µA when suspended. Power control is accomplished
using a combination of 8051 and EZ-USB core resources. The mechanism by which EZ-USB
powers down for suspend, and then re-powers to resume operation, is described in detail in Chapter 11, “EZ-USB Power Management.”
Chapter 2. EZ-USB CPU
Page 2-5
EZ-USB Technical Reference Manual
A suspend operation uses three 8051 resources, the idle mode and two interrupts. Many
enhanced 8051 architectures provide power control similar (or identical) to the EZ-USB enhanced
8051 core.
A USB suspend operation is indicated by a lack of bus activity for 3 ms. The EZ-USB core detects
this, and asserts an interrupt request via the USB interrupt (8051 INT2). The ISR (Interrupt Service Routine) turns off external sub-systems that draw power. When ready to suspend operation,
the 8051 sets an SFR bit, PCON.0. This bit causes the 8051 to suspend, waiting for an interrupt.
When the 8051 sets PCON.0, a control signal from the 8051 to the EZ-USB core causes the core
to shut down the 12-MHz oscillator and internal PLL. This stops all internal clocks to allow the EZUSB core and 8051 to enter a very low power mode.
The suspended EZ-USB chip can be awakened two ways: USB bus activity may resume, or an
EZ-USB pin (WAKEUP#) can be asserted to activate a USB Remote Wakeup. Either event triggers the following chain of events:
•
The EZ-USB core re-starts the 12-MHz oscillator and PLL, and waits for the clocks to stabilize
•
The EZ-USB core asserts a special, high-priority 8051 interrupt to signal a ‘resume’ interrupt.
•
The 8051 vectors to the resume ISR, and upon completion resumes executing code at the
instruction following the instruction that set the PCON.0 bit to 1.
2.9
SFRs
The EZ-USB family was designed to keep 8051 coding as standard as possible, to allow easy integration of existing 8051 software development tools. The added 8051 SFR registers and bits are
summarized in Table 2-2.
Table 2-2. Added Registers and Bits
Page 2-6
8051
Enhancements
SFR
Addr
Function
Dual Data Pointers
DPL0
0x82
Data Pointer 0 Low Addr
DPH0
0x83
Data Pointer 0 High Addr
DPL1
0x84
Data Pointer 1 Low Addr
DPH1
0x85
Data Pointer 1 High Addr
DPS
0x86
Data Pointer Select (LSB)
EZ-USB Technical Reference Manual v1.10
Table 2-2. Added Registers and Bits (Continued)
8051
Enhancements
Timer 2
UART1
SFR
Addr
Function
MPAGE
0x92
Replaces standard 8051 Port 2 for
indirect external data memory
addressing
T2CON.6 0xC8
-7
Timer 2 Control
RCAP2L 0xCA
T2 Capture/Reload Value L
RCAP2H 0xCB
T2 Capture/Reload Value H
T2L
0xCC
T2 Count L
T2H
0xCD
T2 Count H
IE.5
0xA8
ET2-Enable T2 Interrupt Bit
IP.5
0xB8
PT2-T2 Interrupt Priority Control
SCON1.
0-1
0xC0
Serial Port 1 Control
SBUF1
0xC1
Serial Port 1 Data
IE.6
0xA8
ES1-SIO1 Interrupt Enable Bit
IP.6
0xB8 PS1-SIO1 Interrupt Priority Control
EICON.7 0xD8
SMOD1-SIO1 Baud Rate Doubler
Interrupts
INT2-INT5
EXIF
0x91
INT2-INT5 Interrupt Flags
EIE
0xE8
INT2-INT5 Interrupt Enables
EIP.0-3
INT6
WAKEUP#
Idle Mode
2.10
0xF8 INT2-INT5 Interrupt Priority Control
EICON.3 0xD8
INT6 Interrupt Flag
EIE.4
0xE8
INT6 Interrupt Enable
EIP.4
0xF8
INT6 Interrupt Priority Control
EICON.4 0xD8
WAKEUP# Interrupt Flag
EICON.5 0xD8
WAKEUP# Interrupt Enable
PCON.0
0x87
EZ-USB Power Down (Suspend)
Internal Bus
Members of the EZ-USB family that provide pins to expand 8051 memory provide separate nonmultiplexed 16-bit address and 8-bit data busses. This differs from the standard 8051, which multiplexes eight device pins between three sources: IO port 0, the external data bus, and the low byte
of the address bus. A standard 8051 system with external memory requires a de-multiplexing
address latch, strobed by the 8051 ALE (Address Latch Enable) pin. The external latch is not
required by the non-multiplexed EZ-USB chip, and no ALE signal is needed. In addition to elimi-
Chapter 2. EZ-USB CPU
Page 2-7
EZ-USB Technical Reference Manual
nating the customary external latch, the non-multiplexed bus saves one cycle per memory fetch
cycle, further improving 8051 performance.
A standard 8051 user must choose between using Port 0 as a memory expansion port or an IO
port. The AN2131Q provides a separate IO system with its own control registers (in external
memory space), and provides the IO port signals on dedicated (not shared) pins. This allows the
external data bus to be used to expand memory without sacrificing IO pins.
The 8051 is the sole master of the memory expansion bus. It provides read and write signals to
external memory. The address bus is output-only.
A special fast transfer mode gives the EZ-USB family the capability to transfer data to and from
external memory over the expansion bus using a single MOVX instruction, which takes only two
cycles (eight clocks) per byte.
2.11
Reset
The internal 8051 RESET signal is not directly controlled by the EZ-USB RESET pin. Instead, it is
controlled by an EZ-USB register bit accessible to the USB host. When the EZ-USB chip is powered, the 8051 is held in reset. Using the default USB device (enumerated by the USB core), the
host downloads code into RAM. Finally, the host clears an EZ-USB register bit that takes the 8051
out of reset.
The EZ-USB family also operates with external non-volatile memory, in which case the 8051 exits
the reset state automatically at power-on. The various EZ-USB resets and their effects are
described in Chapter 10, "EZ-USB Resets."
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EZ-USB Technical Reference Manual v1.10
Chapter 3
3.1
EZ-USB Memory
Introduction
EZ-USB devices divide RAM into two regions, one for code and data, and the other for USB buffers
and control registers.
7FFF
Registers/Bulk Buffers
7B40
USB Control Registers
(192 bytes)
27FF
2000
1FFF
Data (RD/WR) RAM
If ISODISAB=1
Registers/Bulk Buffers
1FFF/7FFF
1F40/7F40
1F3F/7F3F
16 x 64-byte
Bulk Endpoint Buffers
(1,024 bytes)
1B40/7B40
1B40
1B3F
Data (RD/WR) RAM
Code(PSEN) RAM if
EA=0
(6,976 bytes)
0000
Figure 3-1. EZ-USB 8-KB Memory Map - Addresses are in Hexadecimal
Chapter 3. EZ-USB Memory
Page 3-1
EZ-USB Technical Reference Manual
7FFF
Registers/Bulk Buffers
7B40
USB Control Registers
(192 bytes)
7FFF
7F40
7F3F
13 x 64-byte
Bulk Endpoint Buffers
(832 bytes)
7C00
0FFF
0000
Code(PSEN) and
Data (RD/WR) RAM
(4096 bytes)
Figure 3-2. EZ-USB 4-KB Memory Map - Addresses are in Hexadecimal
3.2
8051 Memory
Figure 3-1 illustrates the two internal EZ-USB RAM regions. 6,976 bytes of general-purpose RAM
occupy addresses 0x0000-0x1B3F. This RAM is loadable by the EZ-USB core or I2C bus
EEPROM, and contains 8051 code and data.
The EZ-USB EA (External Access) pin controls where the bottom segment of code (PSEN) memory is located—inside (EA=0) or outside (EA=1) the EZ-USB chip. If the EZ pin is tied low, the EZUSB core internally ORs the two 8051 read signals PSEN and RD for this region, so that code and
data share the 0x0000-0x1B3F memory space. IF EA=1, all code (PSEN) memory is external.
About 8051 Memory Spaces
The 8051 partitions its memory spaces into code memory and data memory. The 8051 reads
code memory using the signal PSEN# (Program Store Enable), reads data memory using the
signal RD# (Data Read) and writes data memory using the signal WR# (Data Write). The 8051
MOVX (move external) instruction generates RD# or WR# strobes.
PSEN# is a dedicated pin, while the RD# and WR# signals share pins with two IO port signals:
PC7/RD and PC6/WR. Therefore, if expanded memory is used, the port pins PC7 and PC6 are
not available to the system.
1,024 bytes of RAM at 0x7B40-0x7F3F implement the sixteen bulk endpoint buffers. 192 additional bytes at 0x7F40-0x7FFF contain the USB control registers. The 8051 reads and writes this
memory using the MOVX instruction. In the 8-KB RAM EZ-USB version, the 1,024 bulk endpoint
buffer bytes at 0x7B40-0x7F3F also appear at 0x1B40-0x1F3F. This aliasing allows unused bulk
Page 3-2
EZ-USB Technical Reference Manual v1.10
endpoint buffer memory to be added contiguously to the data memory, as illustrated Figure 3-3.
The memory space at 0x1F40-0x1FFF should not be used.
Even though the 8051 can access EZ-USB endpoint buffers at either 0x1B40 or 0x7B40, the firmware should be written to access this memory only at 0x7B40-0x7FFF to maintain compatibility
with future versions of EZ-USB that contain more than 8 KB of RAM. Future versions will have the
bulk buffer space at 0x7B40-0x7F3F only.
1F40
1F00
1EC0
1E80
1E40
1E00
1DC0
1D80
1D40
1D00
1CC0
1C80
1C40
1C00
1BC0
1B80
1B40
1B3F
EP0IN
EP0OUT
EP1IN
EP1OUT
EP2IN
EP2OUT
EP3IN
EP3OUT
EP4IN
EP4OUT
EP5IN
EP5OUT
EP6IN
EP06UT
EP7IN
EP07OUT
Code/Data
RAM
0000
Figure 3-3. Unused Bulk Endpoint Buffers (Shaded) Used as Data Memory
In the example shown in Figure 3-3, only endpoints 0-IN through 3-IN are used for the USB function, so the data RAM (shaded) can be extended to 0x1D7F.
If an application uses none of the 16 EZ-USB isochronous endpoints, the 8051 can set the ISODISAB bit in the ISOCTL register to disable all 16 isochronous endpoints, and make the 2-KB of
isochronous FIFO RAM available as 8051 data RAM at 0x2000-0x27FF.
Setting ISODISAB=1 is an all or nothing choice, as all 16 isochronous endpoints are disabled. An
application that sets this bit must never attempt to transfer data over an isochronous endpoint.
The memory map figures in the remainder of this chapter assume that ISODISAB=0, the default
(and normal) case.
Chapter 3. EZ-USB Memory
Page 3-3
EZ-USB Technical Reference Manual
3.3
Expanding EZ-USB Memory
The 80-pin EZ-USB package provides a 16-bit address bus, an 8-bit bus, and memory control signals PSEN#, RD#, and WR#. These signals are used to expand EZ-USB
memory.
FFFF
Inside EZ-USB
Outside EZ-USB
External
Data
Memory
(RD,WR)
8000
7B40
Registers(RD,WR)
(Note 1)
External
Code
Memory
(PSEN)
External
Data
Memory
(RD, WR)
2000
1FFF
1F3F
1B40
0000
Unused Bulk Buffers
(RD,WR)
Code & Data
(PSEN,RD,WR)
(Note 1)
(Note 2)
Note 1: OK to populate data memory here--RD#, WR#, CS# and OE# pins are inactive.
Note 2: OK to populate code memory here--no PSEN# strobe is generated.
Figure 3-4. EZ-USB Memory Map with EA=0
Figure 3-4 shows that when EA=0, the code/data memory is internal at 0x0000-0x1B40. External
code memory can be added from 0x0000-0xFFFF, but it appears in the memory map only at
0x1B40-0xFFFF. Addressing external code memory at 0x0000-0x1B3F when EA=0 causes the
EZ-USB core to inhibit the #PSEN strobe. This allows program memory to be added from 0x00000xFFFF without requiring decoding to disable it between 0x0000 and 0x1B3F.
Page 3-4
EZ-USB Technical Reference Manual v1.10
The internal block at 0x7B40-0x7FFF (labeled “Registers”) contains the bulk buffer memory and
EZ-USB control registers. As previously mentioned, they are aliased at 0x1B40-0x1FFF to allow
adding unused bulk buffer RAM to general-purpose memory. 8051 code should access this memory only at the 0x7B40-0x7BFF addresses. External RAM may be added from 0x0000 to 0xFFFF,
but the regions shown by Note 1 in Figure 3-4 are ignored; no external strobes or select signals
are generated when the 8051 executes a MOVX instruction that addresses these regions.
3.4
CS# and OE# Signals
The EZ-USB core automatically gates the standard 8051 RD# and WR# signals to exclude selection of external memory that exists internal to the EZ-USB part. The PSEN# signal is also available on a pin for connection to external code memory.
Some 8051 systems implement external memory that is used as both data and program memory.
These systems must logically OR the PSEN# and RD# signals to qualify the chip enable and output enable signals of the external memory. To save this logic, the EZ-USB core provides two additional control signals, CS# and OE# :
•
CS# goes low when RD#, WR#, or PSEN# goes low
•
OE# goes low when RD# or PSEN# goes low
Because the RD#, WR#, and PSEN# signals are already qualified by the addresses allocated to
external memory, these strobes are active only when external memory is accessed.
Chapter 3. EZ-USB Memory
Page 3-5
EZ-USB Technical Reference Manual
FFFF
Inside EZ-USB
Outside EZ-USB
External
Data
Memory
(RD,WR)
8000
7B40
Registers(RD,WR)
(Note 1)
External
Code
Memory
(PSEN)
External
Data
Memory
(RD, WR)
2000
1FFF
1F3F
1B40
Unused Bulk Buffers
(RD,WR)
(Note 1)
Data (RD,WR)
0000
Note 1: OK to populate data memory here--RD#, WR#, CS# and OE# are inactive.
Figure 3-5. EZ-USB Memory Map with EA=1
When EA=1 (Figure 3-5), all code (PSEN) memory is external. All internal EZ-USB RAM is data
memory. This gives the user over 6-KB of general-purpose RAM, accessible by the MOVX
instruction.
Note
Figures 3-4 and 3-5 assume that the EZ-USB chip uses isochronous endpoints, and therefore
that the ISODISAB bit (ISOCTL.0) is LO. If ISODISAB=1, additional data RAM appears internally
at 0x2000-0x27FF, and the RD#, WR#, CS#, and OE# signals are modified to exclude this memory space from external data memory.
Page 3-6
EZ-USB Technical Reference Manual v1.10
Chapter 4
4.1
EZ-USB Input/Output
Introduction
The EZ-USB chip provides two input-output systems:
•
A set of programmable IO pins
•
A programmable I2C Controller
This chapter begins with a description of the programmable IO pins, and shows how they are
shared by a variety of 8051 and EZ-USB alternate functions such as UART, timer and interrupt signals.
The I2C controller uses the SCL and SDA pins, and performs two functions:
•
General-purpose 8051 use
•
Boot loading from an EEPROM
Note
2.2-KB to 4.7-KB pullups are required on the SDA and SCL lines.
This chapter describes both the programming information for the 8051 I2C interface, and the operating details of the I2C boot loader. The role of the boot loader is described in Chapter 5, "EZ-USB
Enumeration and ReNumeration™."
Chapter 4. EZ-USB Input/Output
Page 4-1
EZ-USB Technical Reference Manual
4.2
IO Ports
OE
OUT
Pin
reg
PINS
Figure 4-1. EZ-USB Input/Output Pin
The EZ-USB family implements its IO ports using memory-mapped registers. This is in contrast to
a standard, which uses SFR bits for input/output.
Figure 4-1 shows the basic structure of an EZ-USB IO pin. Twenty-four IO pins are grouped into
three 8-bit ports named PORTA, PORTB, and PORTC. The AN2131Q has all three ports, while
the AN2131S has PORTB, PORTC, and two PORTA bits. The 8051 accesses IO pins using the
three control bits shown in Figure 4-1: OE, OUT, and PINS. The OUT bit writes output data to a
register, the OE bit turns on the output buffer, and the PINS bit indicates the state of the pin.
To configure a pin as an input, the 8051 sets OE=0 to turn off the output buffer. To configure a pin
as an output, the 8051 sets OE=1 to turn on the output buffer, and writes data to the OUT register.
The PINS bit reflects the actual pin value regardless of the value of OE.
A fourth control bit (in PORTACFG, PORTBCFG, PORTCCFG registers) determines whether a
port pin is general-purpose Input/Output (GPIO) as shown in Figure 4-1, or connected to an alternate 8051 or EZ-USB function. Table 4-1 lists the alternate functions available on the IO pins.
Figure 4-1 shows the registers and bits associated with the IO ports.
Table 4-1. IO Pin Functions for PORTxCFG=0 and PORTxCFG=1
PORTxCFG
bit = 0
Page 4-2
PORTxCFG bit = 1
Signal
Signal
Direction
Description
Figure
PA0
T0OUT
OUT
Timer 0 Overflow Pulse
4-2
PA1
T1OUT
OUT
Timer 1 Overflow Pulse
4-2
PA2
OE#
OUT
EZ-USB Output Enable
4-2
PA3
CS#
OUT
EZ-USB Chip Select
4-2
PA4
FWR#
OUT
EZ-USB Fast Write
Strobe
4-2
EZ-USB Technical Reference Manual v1.10
Table 4-1. IO Pin Functions for PORTxCFG=0 and PORTxCFG=1 (Continued)
PORTxCFG
bit = 0
PORTxCFG bit = 1
Signal
Signal
Direction
Description
Figure
PA5
FRD#
OUT
EZ-USB Fast Read
Strobe
4-2
PA6
RxD0OU
T
OUT
UART0 Mode 0 Data
Out
4-2
PA7
RxD1OU
T
OUT
UART1 Mode 0 Data
Out
4-2
PB0
T2
IN
Timer 2 Clock Input
4-3
PB1
T2EX
IN
Timer 2 Capture/Reload
4-3
PB2
RxD1
IN
UART1 Receive Data
4-3
PB3
TxD1
OUT
UART1 Transmit Data
4-2
PB4
INT4
IN
Interrupt 4
4-3
PB5
INT5
IN
Interrupt 5
4-3
PB6
INT6
IN
Interrupt 6
4-3
PB7
T2OUT
OUT
Timer 2 Overflow Pulse
4-2
PC0
RxD0
IN
UART0 Receive Data
4-3
PC1
TxD0
OUT
UART0 Transmit Data
4-2
PC2
INT0#
IN
Interrupt 0
4-3
PC3
INT1#
IN
Interrupt 1
4-3
PC4
T0
IN
Timer 0 Clock Input
4-3
PC5
T1
IN
Timer 1 Clock Input
4-3
PC6
WR#
OUT
Write Strobe
4-2
PC7
RD#
OUT
Read Strobe
4-2
Depending on whether the alternate function is an input or output, the IO logic is slightly different,
as shown in Figure 4-2 (output) and Figure 4-3 (input). The last column of Table 4-1 indicates
which figure applies to each pin.
Chapter 4. EZ-USB Input/Output
Page 4-3
EZ-USB Technical Reference Manual
Alternate Function Output
Alternate Function Output
OE
OE
Pin
OUT
reg
Pin
PINS
OUT
reg
PINS
PORTCFG=0 (port)
PORTCFG=1 (alternate function)
Figure 4-2. Alternate Function is an OUTPUT
Referring to Figure 4-2, when PORTCFG=0, the IO port is selected. In this case the alternate
function (shaded) is disconnected and the pin functions exactly as shown in
Figure 4-1. When PORTCFG=1, the alternate function is connected to the IO pin and the output
register and buffer are disconnected. Note that the 8051 can still read the state of the pin, and
thus the alternate function value.
Alternate Function Input
Alternate Function Input
OE
OE
Pin
OUT
reg
Pin
PINS
OUT
reg
PINS
PORTCFG=0 (port)
PORTCFG=1 (alternate function)
Figure 4-3. Alternate Function is an INPUT
Referring to Figure 4-3, when PORTCFG=0, the IO port is selected. This is the general IO port
shown in Figure 4-1 with one important difference—the alternate function is always listening.
Whether the port pin is set for output or input, the pin signal also drives the alternate function.
8051 firmware should ensure that if the alternate function is not used (if the pin is GPIO only), the
alternate input function is disabled.
For example, suppose the PB4/INT4 pin is configured for PB4. The pin signal is also routed to
INT4. If INT4 is not used by the application, it should not be enabled. Alternatively, enabling INT4
could be useful, allowing IO bit PB4 to trigger an interrupt.
When PORTxCFG=1, the alternate function is selected. The output register and buffer are disconnected. The PINS bit can still read the pin, and thus the input to the alternate function.
Page 4-4
EZ-USB Technical Reference Manual v1.10
4.3
IO Port Registers
PORTACFG
RxD1out
RxD0out
FRD
FWR
CS
OE
T1out
T0out
OUTA
D7
D6
D5
D4
D3
D2
D1
D0
PINSA
D7
D6
D5
D4
D3
D2
D1
D0
OEA
D7
D6
D5
D4
D3
D2
D1
D0
T2OUT
INT6
INT5
INT4
TxD1
RxD1
T2EX
T2
OUTB
D7
D6
D5
D4
D3
D2
D1
D0
PINSB
D7
D6
D5
D4
D3
D2
D1
D0
OEB
D7
D6
D5
D4
D3
D2
D1
D0
PORTCCFG
RD
WR
T1
T0
INT1
INT0
TxD0
RxD0
OUTC
D7
D6
D5
D4
D3
D2
D1
D0
PINSC
D7
D6
D5
D4
D3
D2
D1
D0
OEC
D7
D6
D5
D4
D3
D2
D1
D0
PORTBCFG
Figure 4-4. Registers Associated with PORTS A, B, and C
Figure 4-4 shows the registers associated with the EZ-USB IO ports. The power-on default for the
PORTCFG bits is 0, selecting the IO port function. The power-on default for the OE bits is 0,
selecting the input direction.
Chapter 4. EZ-USB Input/Output
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EZ-USB Technical Reference Manual
4.4
I2C Controller
The USB core contains an I 2C controller for boot loading and general-purpose I 2C bus interface.
This controller uses the SCL (Serial Clock) and SDA (Serial Data) pins. I2C Controller describes
how the boot load operates at power-on to read the contents of an external serial EEPROM to
determine the initial EZ-USB FX configuration. The boot loader operates automatically, while the
8051 is held in reset. The last section of this chapter describes the operating details of the boot
loader.
After the boot sequence completes and the 8051 is brought out of reset, the general-purpose I 2C
controller is available to the 8051 for interface to external I 2C devices, such as other EEPROMS, I/
O chips, audio/video control chips, etc.
4.5
8051 I2C Controller
start
stop
SDA
D7
D6
D5
D4
D3
D2
D1
D0
ACK
SCL
1
2
3
4
5
6
7
8
9
Figure 4-5. General I2C Transfer
Figure 4-5 illustrates the waveforms for an I 2C transfer. SCL and SDA are open-drain EZ-USB
pins, which must be pulled up to Vcc with external resistors. The EZ-USB chip is an I 2C bus master only, meaning that it synchronizes data transfers by generating clock pulses on SCL by driving
low. Once the master drives SCL low, external slave devices can also drive SCL low to extend
clock cycle times.
To synchronize I 2C data, serial data (SDA) is permitted to change state only while SCL is low, and
must be valid while SCL is high. Two exceptions to this rule are used to generate START and
STOP conditions. A START condition is defined as SDA going low, while SCL is high, and a STOP
condition is defined as SDA going high, while SCL is high. Data is sent MSB first. During the last
bit time (clock #9 in Figure 4-5), the master (EZ-USB) floats the SDA line to allow the slave to
acknowledge the transfer by pulling SDA low.
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Multiple I 2C Bus Masters — The EZ-USB chip acts only as an I 2C bus master, never a slave.
However, the 8051 can detect a second master by checking for BERR=1 (Section 4.7, "Status
Bits").
start
SDA
SA3
SA2
SA1
SA0
DA2
DA1
DA0
R/W
ACK
D7
D6
SCL
1
2
3
4
5
6
7
8
9
10
11
Figure 4-6. Addressing an I2C Peripheral
The first byte of an I 2C bus transaction contains the address of the desired peripheral. Figure 4-7
shows the format for this first byte, which is sometimes called a control byte.
A master sends the bit sequence shown in Figure 4-6 after sending a START condition. The master uses this 9-bit sequence to select an I 2C peripheral at a particular address, to establish the
transfer direction (using R/W#), and to determine if the peripheral is present by testing for ACK#.
The four most significant bits SA3-SA0 are the peripheral chip’s slave address. I2C devices are
pre-assigned slave addresses by device type, for example slave address 1010 is assigned to
EEPROMS. The three bits DA2-DA0 usually reflect the states of I2C device address pins.
Devices with three address pins can be strapped to allow eight distinct addresses for the same
device type. The eighth bit (R/W#) sets the direction for the ensuing data transfer, 1 for master
read, and 0 for master write. Most address transfers are followed by one or more data transfers,
with the STOP condition generated after the last data byte is transferred.
In Figure 4-6, a READ transfer follows the address byte (at clock 8, the master sets the R/W# bit
high, indicating READ). At clock 9, the peripheral device responds to its address by asserting
ACK. At clock 10, the master floats SDA and issues SCL pulses to clock in SDA data supplied by
this slave.
Assuming the 12-MHz crystal used by the EZ-USB family, the SCL frequency is 90.9 KHz, giving
an I2C transfer rate of 11 ms per bit.
Chapter 4. EZ-USB Input/Output
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EZ-USB Technical Reference Manual
I2CS
7FA5
I2C Control and Status
b7
b6
b5
b4
b3
b2
b1
b0
START
STOP
LASTRD
ID1
ID0
BERR
ACK
DONE
I2DAT
7FA6
I2C Data
b7
b6
b5
b4
b3
b2
b1
b0
D7
D6
D5
D4
D3
D2
D1
D0
Figure 4-7. FC Registers
The 8051 uses the two registers shown in Figure 4-7 to conduct I2C transfers. The 8051 transfers
data to and from the I2C bus by writing and reading the I2DAT register. The I2CS register controls
I2C transfers and reports various status conditions. The three control bits are START, STOP, and
LASTRD. The remaining bits are status bits. Writing to a status bit has no effect.
4.6
Control Bits
4.6.1 START
The 8051 sets the START bit to 1 to prepare an I2C bus transfer. If START=1, the next 8051 load
to I2DAT will generate the start condition followed by the serialized byte of data in I2DAT. The
8051 loads data in the format shown in Figure 4-5 after setting the START bit. The I2C controller
clears the START bit during the ACK interval (clock 9 in Figure 4-5).
4.6.2 STOP
The 8051 sets STOP=1 to terminate an I2C bus transfer. The I2C controller clears the STOP bit
after completing the STOP condition. If the 8051 sets the STOP bit during a byte transfer, the
STOP condition will be generated immediately following the ACK phase of the byte transfer. If no
byte transfer is occurring when the STOP bit is set, the STOP condition will be carried out immediately on the bus. Data should not be written to I2CS or I2DAT until the STOP bit returns low. In
the 2122/2126 only, an interrupt request is available to signal that STOP bit transmission is complete.
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EZ-USB Technical Reference Manual v1.10
4.6.3 LASTRD
To read data over the I2C bus, an I2C master floats the SDA line and issues clock pulses on the
SCL line. After every eight bits, the master drives SDA low for one clock to indicate ACK. To signal the last byte of the read transfer, the master floats SDA at ACK time to instruct the slave to stop
sending. This is controlled by the 8051 by setting LASTRD=1 before reading the last byte of a
read transfer. The I2C controller clears the LASTRD bit at the end of the transfer (at ACK time).
Note
Setting LASTRD does not automatically generate a STOP condition. The 8051 should also set
the STOP bit at the end of a read transfer.
4.7
Status Bits
After a byte transfer the EZ-USB controller updates the three status bits BERR, ACK, and DONE.
If no STOP condition was transmitted, they are updated at ACK time. If a STOP condition was
transmitted they are updated after the STOP condition is transmitted.
4.7.1 DONE
The I2C controller sets this bit whenever it completes a byte transfer, right after the ACK stage.
The controller also generates an I2C interrupt request (8051 INT3) when it sets the DONE bit. The
I2C controller clears the DONE bit when the 8051 reads or writes the I2DAT register, and the I2C
interrupt request bit whenever the 8051 reads or writes the I2CS or I2DAT register.
4.7.2 ACK
Every ninth SCL of a write transfer, the slave indicates reception of the byte by asserting ACK.
The EZ-USB controller floats SDA during this time, samples the SDA line, and updates the ACK bit
with the complement of the detected value. ACK=1 indicates acknowledge, and ACK=0 indicates
not-acknowledge. The EZ-USB core updates the ACK bit at the same time it sets DONE=1. The
ACK bit should be ignored for read transfers on the bus.
4.7.3 BERR
This bit indicates an I2C bus error. BERR=1 indicates that there was bus contention, which results
when an outside device drives the bus LO when it shouldn’t, or when another bus master wins
Chapter 4. EZ-USB Input/Output
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EZ-USB Technical Reference Manual
arbitration, taking control of the bus. BERR is cleared when the 8051 reads or writes the I2DAT
register.
4.7.4 ID1, ID0
These bits are set by the boot loader (Section 4.10, "I2C Boot Loader") to indicate whether an 8-bit
address or 16-bit address EEPROM at slave address 000 or 001 was detected at power-on. They
are normally used only for debug purposes. Table 4-3 shows the encoding for these bits.
4.8
Sending I2C Data
To send a multiple byte data record over the I2C bus, follow these steps:
1. Set the START bit.
2. Write the peripheral address and direction=0 (for write) to I2DAT.
3. Wait for DONE=1*. If BERR=1 or ACK=0, go to step 7.
4. Load I2DAT with a data byte.
5. Wait for DONE=1*. If BERR=1 or ACK=0 go to step 7.
6. Repeat steps 4 and 5 for each byte until all bytes have been transferred.
7. Set STOP=1.
* If the I2C interrupt (8051 INT3) is enabled, each “Wait for DONE=1” step can be interrupt driven,
and handled by an interrupt service routine. See Section 9.12, "I2C Interrupt", for more details
regarding the I2C interrupt.
4.9
Receiving I2C Data
To read a multiple-byte data record, follow these steps:
1. Set the START bit.
2. Write the peripheral address and direction=1 (for read) to I2DAT.
3. Wait for DONE=1*. If BERR=1 or ACK=0, terminate by setting STOP=1.
4. Read I2DAT and discard the data. This initiates the first burst of nine SCL pulses to clock in
the first byte from the slave.
5. Wait for DONE=1*. If BERR=1, terminate by setting STOP=1.
6. Read the data from I2DAT. This initiates another read transfer.
7. Repeat steps 5 and 6 for each byte until ready to read the second-to-last byte.
8. Before reading the second-to-last I2DAT byte, set LASTRD=1.
9. Read the data from I2DAT. With LASTRD=1, this initiates the final byte read on the I2C bus.
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10. Wait for DONE=1*. If BERR=1, terminate by setting STOP=1.
11. Set STOP=1.
12. Read the last byte from I2DAT immediately (the next instruction) after setting the STOP bit.
This retrieves the last data byte without initiating an extra read transaction (nine more SCL
pulses) on the I2C bus.
2
*If the I C interrupt (8051 INT3) is enabled, each “Wait for DONE=1” step can be interrupt-driven, and handled by an inter2
rupt service routing. See Section 9.12, "I2C Interrupt" for more details regarding the I C interrupt.
4.10
I2C Boot Loader
When the EZ-USB chip comes out of reset, the EZ-USB boot loader checks for the presence of an
EEPROM on its I2C bus. If an EEPROM is detected, the loader reads the first EEPROM byte to
determine how to enumerate (specifically, whether to supply ID information from the EZ-USB core
or from the EEPROM). The various enumeration modes are described in Chapter 5, "EZ-USB
Enumeration and ReNumeration™".
Prior to reading the first EEPROM byte, the boot loader must set an address counter inside the
EEPROM to zero. It does this by sending a control byte (write) to select the EEPROM, followed by
a zero address to set the internal EEPROM address pointer to zero. Then it issues a control byte
(read), and reads the first EEPROM byte.
The EZ-USB boot loader supports two I2C EEPROM types:
•
EEPROMs with address A[7..4]=1010 that use an 8-bit address (example: 24LC00, LC01/
A, LC02/A).
•
EEPROMs with address A[7..4]=1010 that use a 16-bit address (example: 24AA64,
24LC128, 24AA256).
EEPROMs with densities up to 256 bytes require loading a single address byte. Larger EEPROMs
require loading two address bytes.
The EZ-USB I2C controller needs to determine which EEPROM type is connected—one or two
address bytes—so that it can properly reset the EEPROM address pointer to zero before reading
the EEPROM. For the single-byte address part, it must send a single zero byte of address, and for
the two-byte address part it must send two zero bytes of address.
Because there is no direct way to detect which EEPROM type—single or double address—is connected, the I2C controller uses the EEPROM address pins A2, A1, and A0 to determine whether to
send out one or two bytes of address. This algorithm requires that the EEPROM address lines are
strapped as shown in Table 4-2. Single-byte-address EEPROMs are strapped to address 000 and
double-byte-address EEPROMs are strapped to address 001.
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EZ-USB Technical Reference Manual
Table 4-2. Strap Boot EEPROM Address Lines to These Values
Bytes
Example
EEPROM
A2
A1
A0
16
24LC00*
N/A
N/A
N/A
128
24LC01
0
0
0
256
24LC02
0
0
0
4K
24LC32
0
0
1
8K
24LC64
0
0
1
* This EEPROM does not have address pins
The I2C controller performs a three-step test at power-on to determine whether a one-byteaddress or a two-byte-address EEPROM is attached. This test proceeds as follows:
1. The I2C controller sends out a “read current address” command to I2C sub-address 000
(10100001). If no ACK is returned, the controller proceeds to Step 2. If ACK is returned, the
one-byte-address device is indicated. The controller discards the data and proceeds to Step 3.
2. The I2C controller sends out a “read current address” command to I2C sub-address 001
(10100011). If ACK is returned, the two-byte-address device is indicated. The controller discards the data and proceeds to Step 3. If no ACK is returned, the controller assumes that a
valid EEPROM is not connected, assumes the “No Serial EEPROM” mode, and terminates
the boot load.
3. The I2C controller resets the EEPROM address pointer to zero (using the appropriate number
of address bytes), then reads the first EEPROM byte. If it does not read 0xB0 or 0xB2, the
controller assumes the “No Serial EEPROM” mode. If it reads either 0xB0 or 0xB2, the controller copies the next six bytes into internal storage, and if it reads 0xB2, it proceeds to load
the EEPROM contents into internal RAM.
The results of this power-on test are reported in the ID1 and ID0 bits, as shown in Table 4-3.
Table 4-3. Results of Power-On I2C Test
ID1
ID0
0
0
No EEPROM detected
Meaning
0
1
One-byte-address load EEPROM detected
1
0
Two-byte-address load EEPROM detected
1
1
Not used
Other EEPROM devices (with device address of 1010) can be attached to the I2C bus for general
purpose 8051 use, as long as they are strapped for address other than 000 or 001. If a 24LC00
EEPROM is used, no other EEPROMS with device address 1010 may be used, because the
24LC00 responds to all eight sub-addresses.
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EZ-USB Technical Reference Manual v1.10
Chapter 5
5.1
EZ-USB Enumeration and ReNumeration™
Introduction
The EZ-USB chip is soft. 8051 code and data is stored in internal RAM, which is loaded from the
host using the USB interface. Peripheral devices that use the EZ-USB chip can operate without
ROM, EPROM, or FLASH memory, shortening production lead times and making firmware updates
a breeze.
To support the soft feature, the EZ-USB chip automatically enumerates as a USB device without
firmware, so the USB interface itself may be used to download 8051 code and descriptor tables.
The EZ-USB core performs this initial (power-on) enumeration and code download while the 8051
is held in reset. This initial USB device, which supports code download, is called the “Default USB
Device.”
After the code descriptor tables have been downloaded from the host to EZ-USB RAM, the 8051 is
brought out of reset and begins executing the device code. The EZ-USB device enumerates
again, this time as the loaded device. This second enumeration is called “ReNumeration,” which
the EZ-USB chip accomplishes by electrically simulating a physical disconnection and re-connection to the USB.
An EZ-USB control bit called “ReNum” (ReNumerated) determines which entity, the core or the
8051, handles device requests over endpoint zero. At power-on, the RENUM bit (USBCS.1) is
zero, indicating that the EZ-USB core automatically handles device requests. Once the 8051 is
running, it can set ReNum=1 to indicate that user 8051 code handles subsequent device requests
using its downloaded firmware. Chapter 7, "EZ-USB Endpoint Zero" describes how the 8051 handles device requests while ReNum=1.
It is also possible for the 8051 to run with ReNum=0 and have the EZ-USB core handle certain
endpoint zero requests (see the text box, “Another Use for the Default USB Device” on page 5-2).
This chapter deals with the various EZ-USB startup modes, and describes the default USB device
that is created at initial enumeration.
Chapter 5. EZ-USB Enumeration and ReNumeration™
Page 5-1
EZ-USB Technical Reference Manual
Another Use for the Default USB Device
The Default USB Device is established at power-on to set up a USB device capable of downloading firmware into EZ-USB RAM. Another useful feature of the EZ-USB default device is that
8051 code can be written to support the already-configured Generic USB device. Before bringing the 8051 out of reset, the EZ-USB core enables certain endpoints and reports them to the
host via descriptors. By utilizing the USB default machine (by keeping ReNum=0), the 8051 can,
with very little code, perform meaningful USB transfers that use these default endpoints. This
accelerates the USB learning curve. To see an example of how little code is actually necessary,
take a look at Section 6.11, "Polled Bulk Transfer Example."
5.2
The Default USB Device
The Default USB Device consists of a single USB configuration containing one interface (interface
0) with three alternate settings 0, 1, and 2. The endpoints reported for this device are shown in
Table 5-1. Note that alternate setting zero uses no interrupt or isochronous bandwidth, as recommended by the USB Specification.
Table 5-1. EZ-USB Default Endpoints
Endpoint
Type
Alternate Setting
0
1
2
Maximum Packet Size (Bytes)
0
CTL
64
64
64
1-IN
INT
0
16
64
2-IN
BULK
0
64
64
2-OUT
BULK
0
64
64
4-IN
BULK
0
64
64
4-OUT
BULK
0
64
64
6-IN
BULK
0
64
64
6-OUT
BULK
0
64
64
8-IN
ISO
0
16
256
8-OUT
ISO
0
16
256
9-IN
ISO
0
16
16
9-OUT
ISO
0
16
16
10-IN
ISO
0
16
16
10 OUT
ISO
0
16
16
For purposes of downloading 8051 code, the Default USB Device requires only CONTROL endpoint zero. Nevertheless, the USB default machine is enhanced to support other endpoints as
shown in Figure 5-1 (note the alternate settings 1 and 2). This enhancement is provided to allow
the developer to get a head start generating USB traffic and learning the USB system. All the
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EZ-USB Technical Reference Manual v1.10
descriptors are automatically handled by the EZ-USB core, so the developer can immediately start
writing code to transfer data over USB using these pre-configured endpoints.
When the EZ-USB core establishes the Default USB Device, it also sets the proper endpoint configuration bits to match the descriptor data supplied by the EZ-USB core. For example, bulk endpoints 2, 4, and 6 are implemented in the Default USB Device, so the EZ-USB core sets the
corresponding EPVAL bits. Chapter 6, “EZ-Bulk Transfers” contains a detailed explanation of the
EPVAL bits.
Tables 5-9 through 5-13 show the various descriptors returned to the host by the EZ-USB core
when ReNum=0. These tables describe the USB endpoints defined in Table 5-1, along with other
USB details, and should be useful to help understand the structure of USB descriptors.
5.3
EZ-USB Core Response to EP0 Device Requests
Table 5-2 shows how the EZ-USB core responds to endpoint zero requests when ReNum=0.
Table 5-2. How the EZ-USB Core Handles EP0 Requests When ReNum=0
bRequest
Name
Action: ReNum=0
0x00
Get Status/Device
Returns two zero bytes
0x00
Get Status/Endpoint
Supplies EP Stall bit for indicated EP
0x00
Get Status/Interface
Returns two zero bytes
0x01
Clear Feature/Device
None
0x01
Clear Feature/Endpoint
Clears Stall bit for indicated EP
0x02
(reserved)
None
0x03
Set Feature/Device
None
0x03
Set Feature Endpoint
Sets Stall bit for indicated EP
0x04
(reserved)
None
0x05
Set Address
Updates FNADD register
0x06
Get Descriptor
Supplies internal table
0x07
Set Descriptor
None
0x08
Get Configuration
Returns internal value
0x09
Set Configuration
Sets internal value
0x0A
Get Interface
Returns internal value (0-3)
0x0B
Set Interface
Sets internal value (0-3)
0x0C
Sync Frame
None
Vendor Requests
0x0A
Firmware Load
Upload/Download RAM
0xA10xAF
Reserved
Reserved by Cypress Semiconductor
all other
Chapter 5. EZ-USB Enumeration and ReNumeration™
None
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EZ-USB Technical Reference Manual
The USB host enumerates by issuing:
•
Set_Address
•
Get_Descriptor
•
Set_Configuration (to 1)
As shown in Table 5-2, after enumeration, the EZ-USB core responds to the following host
requests.
•
Set or clear an endpoint stall (Set/Clear Feature-Endpoint).
•
Read the stall status for an endpoint (Get_Status_Endpoint).
•
Set/Read an 8-bit configuration number (Set/Get_Configuration).
•
Set/Read a 2-bit interface alternate setting (Set/Get_Interface).
•
Download or upload 8051 RAM.
To ensure proper operation of the default Keil Monitor, which uses SIO-1 (RXD1 and TXD1), never
change the following Port Config bits from “1”:
•
PORTBCFG bits 2 (RXD1) and 3 (TXD1).
To ensure the 8051 processor can access the external SRAM (including the Keil Monitor), do not
change the following bits from “1”:
•
PORTCCFG bits 6 (WR#) and 7 (RD#).
To ensure that no bits are unintentionally changed, all writes to the PORTxCFG registers should
use a read-modify-write series of instructions.
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5.4
Firmware Load
The USB Specification provides for vendor-specific requests to be sent over CONTROL endpoint
zero. The EZ-USB chip uses this feature to transfer data between the host and EZ-USB RAM.
The EZ-USB core responds to two “Firmware Load” requests, as shown in Tables 5-3 and 5-4.
Table 5-3. Firmware Download
Byte
Field
Value
Meaning
0
bmRequest
0x40
Vendor Request,
OUT
1
bRequest
0xA0
“Firmware Load”
2
wValueL
AddrL
Starting Address
3
wValueH
AddrH
4
wIndexL
0x00
5
wIndexH
0x00
6
wLenghtL
LenL
7
wLengthH
LenH
8051
Response
None
required
Number of Bytes
Table 5-4. Firmware Upload
Byte
Field
Value
Meaning
0
bmRequest
0xC0
Vendor Request,
IN
1
bRequest
0xA0
“Firmware Load”
2
wValueL
AddrL
Starting Address
3
wValueH
AddrH
4
wIndexL
0x00
5
wIndexH
0x00
6
wLengthL
LenL
7
wLengthH
LenH
8051
Response
None
required
Number of Bytes
These requests are always handled by the EZ-USB core (ReNum=0 or 1). This means that 0xA0
is reserved by the EZ-USB chip, and therefore should never be used for a vendor request.
Cypress Semiconductor also reserves bRequest values 0xA1 through 0xAF, so your system
should not use these bRequest values.
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EZ-USB Technical Reference Manual
A host loader program typically writes 0x01 to the CPUCS register to put the 8051 into RESET,
loads all or part of the EZ-USB RAM with 8051 code, and finally reloads the CPUCS register with
0 to take the 8051 out of RESET. The CPUCS register is the only USB register that can be written
using the Firmware Download command.
Firmware loads are restricted to internal EZ-USB memory.
When ReNum=1 at Power-On
At power-on, the ReNum bit is normally set to zero so that the EZ-USB handles device requests
over CONTROL endpoint zero. This allows the core to download 8051 firmware and then reconnect as the target device.
At power-on, the EZ-USB core checks the I2C bus for the presence of an EEPROM. If it finds
one, and the first byte of the EEPROM is 0xB2, the core copies the contents of the EEPROM into
internal RAM, sets the ReNum bit to 1, and un-RESETS the 8051. The 8051 wakes up ready-torun firmware in RAM. The required data form for this load module is described in the next section.
5.5
Enumeration Modes
When the EZ-USB chip comes out of reset, the EZ-USB core makes a decision about how to enumerate based on the contents of an external EEPROM on its I2C bus. Table 5-5 shows the
choices. In Table 5-5, PID means Product ID, VID means Version ID, and DID means Device ID.
Table 5-5. EZ-USB Core Action at Power-Up
First EEPROM
byte
EZ-USB Core Action
Not 0xB0 or 0xB2
Supplies descriptors, PID/VID/DID from EZUSB Core. Sets ReNum=0.
0xB0
Supplies descriptors from EZ-USB core,
PID/VID/DID from EEPROM. Sets
ReNum=0.
0xB2
Loads EEPROM into EZ-USB RAM. Sets
ReNum=1; therefore 8051 supplies descriptors, PID/VID/DID.
If no EEPROM is present, or if one is present but the first byte is neither 0xB0 nor 0xB2, the EZUSB core enumerates using internally stored descriptor data, which contains the Cypress Semiconductor VID, PID, and DID. These ID bytes cause the host operating system to load a Cypress
Semiconductor device driver. The EZ-USB core also establishes the Default USB device. This
mode is only used for code development and debug.
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If a serial EEPROM is attached to the I2C bus and its first byte is 0xB0, the EZ-USB core enumerates with the same internally stored descriptor data as for the no-EEPROM case, but with one difference. It supplies the PID/VID/DID data from six bytes in the external EEPROM rather than from
the EZ-USB core. The custom VID/PID/DID in the EEPROM causes the host operating system to
load a device driver that is matched to the EEPROM VID/PID/DID. This EZ-USB operating mode
provides a soft USB device using ReNumeration.
If a serial EEPROM is attached to the I2C bus and its first byte is 0xB2, the EZ-USB core transfers
the contents of the EEPROM into internal RAM. The EZ-USB core also sets the ReNum bit to 1 to
indicate that the 8051 (and not the EZ-USB core) responds to device requests over CONTROL
endpoint zero (see the text box, “When ReNum=1 at Power-On” on page 5-6). Therefore, all
descriptor data, including VID/DID/PID values, are supplied by the 8051 firmware. The last byte
loaded from the EEPROM (to the CPUCS register) releases the 8051 reset signal, allowing the
EZ-USB chip to come up as a fully custom device with firmware in RAM.
The following sections discuss these enumeration methods in detail.
The Other Half of the I2C Story
The EZ-USB I2C controller serves two purposes. First, as described in this chapter, it manages
the serial EEPROM interface that operates automatically at power-on to determine the enumeration method. Second, once the 8051 is up and running, the 8051 can access the I2C controller
for general-purpose use. This makes a wide range of standard I2C peripherals available to an
EZ-USB system.
Other I2C devices can be attached to the SCL and SDA lines of the I2C bus as long as there is no
address conflict with the serial EEPROM described in this chapter. Chapter 4, "EZ-USB Input/
Output" describes the general-purpose nature of the I2C interface.
5.6
No Serial EEPROM
In the simplest case, no serial EEPROM is present on the I2C bus, or an EEPROM is present but
its first byte is not 0xB0 or 0xB2. In this case, descriptor data is supplied by a table internal to the
EZ-USB core. The EZ-USB chip comes on as the USB Default Device, with the ID bytes shown in
Table 5-6.
Table 5-6. EZ-USB Device Characteristics, No Serial EEPROM
Vendor ID
0x0547 (Cypress Semiconductor)
Product ID
0x2131 (EZ-USB)
Device Release
0xXXYY (depends on revision)
Chapter 5. EZ-USB Enumeration and ReNumeration™
Page 5-7
EZ-USB Technical Reference Manual
The USB host queries the device during enumeration, reads the device descriptor, and uses the
Table 5-6 bytes to determine which software driver to load into the operating system. This is a
major USB feature—drivers are dynamically matched with devices and automatically loaded when
a device is plugged in.
The no_EEPROM case is the simplest configuration, but also the most limiting. This mode is used
only for code development, utilizing Cypress software tools matched to the ID values in Table 5-6.
Reminder
The EZ-USB core uses the Table 5-6 data for enumeration only if the ReNum bit is zero. If
ReNum=1, enumeration data is supplied by 8051 code.
5.7
Serial EEPROM Present, First Byte is 0xB0
Table 5-7. EEPROM Data Format for “B0” Load
EEPROM
Address
Contents
0
0xB0
1
Vendor ID (VID) L
2
Vendor ID (VID) H
3
Product ID (PID) L
4
Product ID (PID) H
5
Device ID (DID) L
6
Device ID (DID) H
7
Not used
If, at power-on, the EZ-USB core detects an EEPROM connected to its I2C port with the value
0xB0 at address 0, the EZ-USB core copies the Vendor ID (VID), Product ID (PID), and Device ID
(DID) from the EEPROM (Table 5-7) into internal storage. The EZ-USB core then supplies these
bytes to the host as part of the Get_Descriptor-Device request. (These six bytes replace only the
VID/PID/DID bytes in the default USB device descriptor.) This causes a driver matched to the
VID/PID/DID values in the EEPROM, instead of those in the EZ-USB core, to be loaded into the
OS.
After initial enumeration, the driver downloads 8051 code and USB descriptor data into EZ-USB
RAM and starts the 8051. The code then ReNumerates to come on as the fully custom device.
A recommended EEPROM for this application is the Microchip 24LC00, a small (5-pin SOT package) inexpensive 16-byte serial EEPROM. A 24LC01 (128 bytes) or 24LC02 (256 bytes) may be
substituted for the 24LC00, but as with the 24LC00, only the first seven bytes are used.
Page 5-8
EZ-USB Technical Reference Manual v1.10
5.8
Serial EEPROM Present, First Byte is 0xB2
If, at power-on, the EZ-USB core detects an EEPROM connected to its I2C port with the value
0xB2 at address 0; the EZ-USB core loads the EEPROM data into EZ-USB RAM. It also sets the
ReNum bit to 1, causing device requests to be fielded by the 8051 instead of the EZ-USB core.
The EEPROM data format is shown in Table 5-8.
Table 5-8. EEPROM Data Format for “B2” Load
EEPROM
Address
Contents
0
0xB2
1
Vendor ID (VID) L
2
Vendor ID (VID) H
3
Product ID (PID) L
4
Product ID (PID) H
5
Device ID (DID) L
6
Device ID (DID) H
7
Length H
8
Length L
9
StartAddr H
10
StartAddr L
---
Data block
-----
Length H
---
Length L
---
StartAddr H
---
StartAddr L
---
Data block
-----
0x80
---
0x01
---
0x7F
---
0x92
--Last
00000000
The first byte tells the EZ-USB core to copy EEPROM data into RAM. The next six bytes (1-6) are
ignored (see the text box, “VID/PID/DID in a “B2” EEPROM” on page 5-10).
Chapter 5. EZ-USB Enumeration and ReNumeration™
Page 5-9
EZ-USB Technical Reference Manual
One or more data records follow, starting at EEPROM address 7. The maximum value of Length
H is 0x03, allowing a maximum of 1,023 bytes per record. Each data record consists of a length,
a starting address, and a block of data bytes. The last data record must have the MSB of its
Length H byte set to 1. The last data record consists of a single-byte load to the CPUCS register
at 0x7F92. Only the LSB of this byte is significant—8051RES (CPUCS.0) is set to zero to bring
the 8051 out of reset.
Serial EEPROM data can be loaded into two EZ-USB RAM spaces only.
•
8051 program/data RAM at 0x0000-0x1B40.
•
The CPUCS register at 0x7F92 (only bit 0, 8051 RESET, is host-loadable).
VID/PID/DID in a “B2” EEPROM
Bytes 1-6 of a B2 EEPROM can be loaded with VID/PID/DID bytes if it is desired at some point to
run the 8051 program with ReNum=0 (EZ-USB core handles device requests), using the
EEPROM VID/PID/DID rather than the Cypress Semiconductor values built into the EZ-USB
core.
5.9
ReNumeration
Three EZ-USB control bits in the USBCS (USB Control and Status) register control the ReNumeration process: DISCON, DISCOE, and RENUM.
USBCS
USB Control and Status
7FD6
b7
b6
b5
b4
b3
b2
b1
b0
WAKESRC
-
-
-
DISCON
DISCOE
RENUM
SIGRSUME
R/W
R
R
R
R/W
R/W
R/W
R/W
0
0
0
0
0
1
0
0
Figure 5-1. USB Control and Status Register
Page 5-10
EZ-USB Technical Reference Manual v1.10
Internal Logic
DISCON
DISCON#
pin
DISCOE
Figure 5-2. Disconnect Pin Logic
The logic for the DISCON and DISCOE bits is shown in Figure 5-2. To simulate a USB disconnect,
the 8051 writes the value 00001010 to USBCS. This floats the DISCON# pin, and provides an
internal DISCON signal to the USB core that causes it to perform disconnect housekeeping.
To re-connect to USB, the 8051 writes the value 00000110 to USBCS. This presents a logic HI to
the DISCON# pin, enables the output buffer, and sets the RENUM bit HI to indicate that the 8051
(and not the USB core) is now in control for USB transfers. This arrangement allows connecting
the 1,500-ohm resistor directly between the DISCON# pin and the USB D+ line (Figure 5-3).
DISCON#
EZ-USB
To 3.3V regulator
1500
J1
VCC
DD+
GND
1
2
3
4
DD+
USB-B
Figure 5-3. Typical Disconnect Circuit (DISCOE=1)
5.10
Multiple ReNumerations
The 8051 can ReNumerate anytime. One use for this capability might be to fine tune an isochronous endpoint’s bandwidth requests by trying various descriptor values and ReNumerating.
Chapter 5. EZ-USB Enumeration and ReNumeration™
Page 5-11
EZ-USB Technical Reference Manual
5.11
Default Descriptor
Tables 5-9 through 5-19 show the descriptor data built into the EZ-USB core. The tables are presented in the order that the bytes are stored.
Table 5-9. USB Default Device Descriptor
Offset
0
Field
Description
Value
bLength
Length of this Descriptor = 18 bytes
12H
1
bDescriptorType
Descriptor Type = Device
01H
2
bcdUSB (L)
USB Specification Version 1.00 (L)
00H
3
bcdUSB (H)
USB Specification Version 1.00 (H)
01H
4
bDeviceClass
Device Class (FF is Vendor-Specific)
FFH
5
bDeviceSubClass
Device Sub-Class (FF is Vendor-Specific)
FFH
6
bDeviceProtocol
Device Protocol (FF is Vendor-Specific)
FFH
7
bMaxPacketSize0
Maximum Packet Size for EP0 = 64 bytes
40H
8
idVendor (L)
Vendor ID (L)
47H
Cypress Semiconductor = 0547H
9
idVendor (H)
Vendor ID (H)
10
idProduct (L)
Product ID (L)
05H
11
idProduct (H)
Product ID (H)
21H
12
bcdDevice (L)
Device Release Number (BCD,L) (see individual
data sheet)
21H
13
bcdDevice (H)
Device Release Number (BCD,H) (see individual
data sheet)
YYH
14
iManufacturer
Manufacturer Index String = None
00H
15
iProduct
Product Index String = None
00H
16
iSerialNumber
Serial Number Index String = None
00H
17
bNumConfigurations
Number of Configurations in this Interface = 1
01H
EZ-USB = 2131H
31H
The Device Descriptor specifies a MaxPacketSize of 64 bytes for endpoint 0, contains Cypress
Semiconductor Vendor, Product and Release Number IDs, and uses no string indices. Release
Number IDs (XX and YY) are found in individual Cypress Semiconductor data sheets. The EZUSB core returns this information response to a “Get_Descriptor/Device” host request.
Page 5-12
EZ-USB Technical Reference Manual v1.10
Table 5-10. USB Default Configuration Descriptor
Offset
Field
Description
Value
0
bLength
Length of this Descriptor = 9 bytes
09H
1
bDescriptorType
Descriptor Type = Configuration
02H
2
wTotalLength (L)
Total Length (L) Including Interface and Endpoint
Descriptors
DAH
3
wTotalLength (H)
Total Length (H)
00H
4
bNumInterfaces
Number of Interfaces in this Configuration
01H
5
bConfigurationValue
Configuration Value Used by Set_Configuration
Request to Select this Configuration
01H
6
iConfiguration
Index of String Describing this Configuration = None
00H
7
bmAttributes
Attributes - Bus-Powered, No Wakeup
80H
8
MaxPower
Maximum Power - 100 mA
32H
The configuration descriptor includes a total length field (offset 2-3) that encompasses all interface
and endpoint descriptors that follow the configuration descriptor. This configuration describes a
single interface (offset 4). The host selects this configuration by issuing a Set_Configuration
requests specifying configuration #1 (offset 5).
Table 5-11. USB Default Interface 0, Alternate Setting 0 Descriptor
Offset
Field
Description
Value
0
bLength
Length of the Interface Descriptor
09H
1
bDescriptorType
Descriptor Type = Interface
04H
2
bInterfaceNumber
Zero-based Index of this Interface = 0
00H
3
bAlternateSetting
Alternate Setting Value = 0
00H
4
bNumEndpoints
Number of Endpoints in this Interface (Not Counting
EPO) = 0
00H
5
bInterfaceClass
Interface Class = Vendor Specific
FFH
6
bInterfaceSubClass
Interface Sub-class = Vendor Specific
FFH
7
bInterfaceProtocol
Interface Protocol = Vendor Specific
FFH
8
iInterface
Index to String Descriptor for this Interface = None
00H
Interface 0, alternate setting 0 describes endpoint 0 only. This is a zero bandwidth setting. The
interface has no string index.
Chapter 5. EZ-USB Enumeration and ReNumeration™
Page 5-13
EZ-USB Technical Reference Manual
Table 5-12. USB Default Interface 0, Alternate Setting 1 Descriptor
Offset
Field
Description
Value
0
bLength
Length of the Interface Descriptor
09H
1
bDescriptorType
Descriptor Type = Interface
04H
2
bInterfaceNumber
Zero-based Index of this Interface = 0
00H
3
bAlternateSetting
Alternate Setting Value = 1
01H
4
bNumEndpoints
Number of Endpoints in this Interface (Not Counting
EPO) = 13
0DH
5
bInterfaceClass
Interface Class = Vendor Specific
FFH
6
bInterfaceSubClass
Interface Sub-class = Vendor Specific
FFH
7
bInterfaceProtocol
Interface Protocol = Vendor Specific
FFH
8
iInterface
Index to String Descriptor for this Interface = None
00H
Interface 0, alternate setting 1 has thirteen endpoints, whose individual descriptors follow the interface descriptor. The alternate settings have no string indices.
Table 5-13. USB Default Interface 0, Alternate Setting 1, Interrupt Endpoint Descriptor
Offset
Field
Description
Value
0
bLength
Length of this Endpoint Descriptor
07H
1
bDescriptorType
Descriptor Type = Endpoint
05H
2
bEndpointAddress
Endpoint Direction (1 is in) and Address = IN1
81H
3
bmAttributes
XFR Type = INT
03H
4
wMaxPacketSize (L)
Maximum Packet Size = 16 Bytes
10H
5
wMaxPacketSize (H)
Maximum Packet Size - High
00H
6
bInterval
Polling Interval in Milliseconds = 10 ms
0AH
Interface 0, alternate setting 1 has one interrupt endpoint, IN1, which has a maximum packet size
of 16 and a polling interval of 10 ms.
Page 5-14
EZ-USB Technical Reference Manual v1.10
Table 5-14. USB Default Interface 0, Alternate Setting 1, Bulk Endpoint Descriptors
Offset
Field
Description
Value
0
bLength
Length of this Endpoint Descriptor
07H
1
bDescriptorType
Descriptor Type = Endpoint
05H
2
bEndpointAddress
Endpoint Direction (1 is in) and Address = IN2
82H
3
bmAttributes
XFR Type = BULK
02H
4
wMaxPacketSize (L)
Maximum Packet Size = 64 Bytes
40H
5
wMaxPacketSize (H)
Maximum Packet Size - High
00H
6
bInterval
Polling Interval in Milliseconds (1 for iso)
00H
0
bLength
Length of this Endpoint Descriptor
07H
1
bDescriptorType
Descriptor Type = Endpoint
05H
2
bEndpointAddress
Endpoint Direction (1 is in) and Address = OUT2
02H
3
bmAttributes
XFR Type = BULK
02H
4
wMaxPacketSize (L)
Maximum Packet Size = 64 Bytes
40H
5
wMaxPacketSize (H)
Maximum Packet Size - High
00H
6
bInterval
Polling Interval in Milliseconds (1 for iso)
00H
0
bLength
Length of this Endpoint Descriptor
07H
1
bDescriptorType
Descriptor Type = Endpoint
05H
2
bEndpointAddress
Endpoint Direction (1 is in) and Address = IN4
84H
3
bmAttributes
XFR Type = BULK
02H
4
wMaxPacketSize (L)
Maximum Packet Size = 64 Bytes
40H
5
wMaxPacketSize (H)
Maximum Packet Size - High
00H
6
bInterval
Polling Interval in Milliseconds (1 for iso)
00H
0
bLength
Length of this Endpoint Descriptor
07H
1
bDescriptorType
Descriptor Type = Endpoint
05H
2
bEndpointAddress
Endpoint Direction (1 is in) and Address = OUT4
04H
3
bmAttributes
XFR Type = BULK
02H
4
wMaxPacketSize (L)
Maximum Packet Size = 64 Bytes
40H
5
wMaxPacketSize (H)
Maximum Packet Size - High
00H
6
bInterval
Polling Interval in Milliseconds (1 for iso)
00H
0
bLength
Length of this Endpoint Descriptor
07H
1
bDescriptorType
Descriptor Type = Endpoint
05H
2
bEndpointAddress
Endpoint Direction (1 is in) and Address = IN6
86H
3
bmAttributes
XFR Type = BULK
02H
4
wMaxPacketSize (L)
Maximum Packet Size = 64 Bytes
40H
5
wMaxPacketSize (H)
Maximum Packet Size - High
00H
6
bInterval
Polling Interval in Milliseconds (1 for iso)
00H
Chapter 5. EZ-USB Enumeration and ReNumeration™
Page 5-15
EZ-USB Technical Reference Manual
Table 5-14. USB Default Interface 0, Alternate Setting 1, Bulk Endpoint Descriptors (Continued)
Offset
Field
Description
Value
0
bLength
Length of this Endpoint Descriptor
07H
1
bDescriptorType
Descriptor Type = Endpoint
05H
2
bEndpointAddress
Endpoint Direction (1 is in) and Address = OUT6
06H
3
bmAttributes
XFR Type = BULK
02H
4
wMaxPacketSize (L)
Maximum Packet Size = 64 Bytes
40H
5
wMaxPacketSize (H)
Maximum Packet Size - High
00H
6
bInterval
Polling Interval in Milliseconds (1 for iso)
00H
Interface 0, alternate setting 1 has six bulk endpoints with max packet sizes of 64 bytes. Even
numbered endpoints were chosen to allow endpoint pairing. For more on endpoint pairing, see
Chapter 6, "EZ-USB Bulk Transfers."
Page 5-16
EZ-USB Technical Reference Manual v1.10
Table 5-15. USB Default Interface 0, Alternate Setting 1, Isochronous Endpoint Descriptors
Offset
0
1
2
3
4
5
6
0
1
2
3
4
5
6
0
1
2
3
4
5
6
0
1
2
3
4
5
6
0
1
2
3
4
5
6
0
1
2
3
4
5
6
Field
bLength
bDescriptorType
bEndpointAddress
bmAttributes
wMaxPacketSize (L)
wMaxPacketSize (H)
bInterval
bLength
bDescriptorType
bEndpointAddress
bmAttributes
wMaxPacketSize (L)
wMaxPacketSize (H)
bInterval
bLength
bDescriptorType
bEndpointAddress
bmAttributes
wMaxPacketSize (L)
wMaxPacketSize (H)
bInterval
bLength
bDescriptorType
bEndpointAddress
bmAttributes
wMaxPacketSize (L)
wMaxPacketSize (H)
bInterval
bLength
bDescriptorType
bEndpointAddress
bmAttributes
wMaxPacketSize (L)
wMaxPacketSize (H)
bInterval
bLength
bDescriptorType
bEndpointAddress
bmAttributes
wMaxPacketSize (L)
wMaxPacketSize (H)
bInterval
Description
Length of this Endpoint Descriptor
Descriptor Type = Endpoint
Endpoint Direction (1 is in) and Address = IN8
XFR Type = ISO
Maximum Packet Size = 16 Bytes
Maximum Packet Size - High
Polling Interval in Milliseconds (1 for iso)
Length of this Endpoint Descriptor
Descriptor Type = Endpoint
Endpoint Direction (1 is in) and Address = OUT8
XFR Type = ISO
Maximum Packet Size = 16 Bytes
Maximum Packet Size - High
Polling Interval in Milliseconds (1 for iso)
Length of this Endpoint Descriptor
Descriptor Type = Endpoint
Endpoint Direction (1 is in) and Address = IN9
XFR Type = ISO
Maximum Packet Size = 16 Bytes
Maximum Packet Size - High
Polling Interval in Milliseconds (1 for iso)
Length of this Endpoint Descriptor
Descriptor Type = Endpoint
Endpoint Direction (1 is in) and Address = OUT9
XFR Type = ISO
Maximum Packet Size = 16 Bytes
Maximum Packet Size - High
Polling Interval in Milliseconds (1 for iso)
Length of this Endpoint Descriptor
Descriptor Type = Endpoint
Endpoint Direction (1 is in) and Address = IN10
XFR Type = ISO
Maximum Packet Size = 16 Bytes
Maximum Packet Size - High
Polling Interval in Milliseconds (1 for iso)
Length of this Endpoint Descriptor
Descriptor Type = Endpoint
Endpoint Direction (1 is in) and Address = OUT10
XFR Type = ISO
Maximum Packet Size = 16 Bytes
Maximum Packet Size - High
Polling Interval in Milliseconds (1 for iso)
Chapter 5. EZ-USB Enumeration and ReNumeration™
Value
07H
05H
88H
01H
10H
00H
01H
07H
05H
08H
01H
10H
00H
01H
07H
05H
89H
01H
10H
00H
01H
07H
05H
09H
01H
10H
00H
01H
07H
05H
8AH
01H
10H
00H
01H
07H
05H
0AH
01H
10H
00H
01H
Page 5-17
EZ-USB Technical Reference Manual
Interface 0, alternate setting 1 has six isochronous endpoints with maximum packet sizes of 16
bytes. This is a low bandwidth setting.
Table 5-16. USB Default Interface 0, Alternate Setting 2 Descriptor
Offset
Field
Description
Value
0
bLength
Length of the Interface Descriptor
09H
1
bDescriptor Type
Descriptor Type = Interface
04H
2
bInterfaceNumber
Zero-based Index of this Interface = 0
00H
3
bAlternateSetting
Alternate Setting Value = 2
02H
4
bNumEndpoints
Number of Endpoints in this Interface (Not Counting
EPO) = 13
0DH
5
bInterfaceClass
Interface Class = Vendor Specific
FFH
6
bInterfaceSubClass
Interface Sub-class = Vendor Specific
FFH
7
bInterfaceProtocol
Interface Protocol = Vendor Specific
FFH
8
iInterface
Index to String Descriptor for this Interface = None
00H
Interface 0, alternate setting 2 has thirteen endpoints, whose individual descriptors follow the interface descriptor. Alternate setting 2 differs from alternate setting 1 in the maximum packet sizes of
its interrupt endpoint and two of its isochronous endpoints (EP8IN and EP8OUT).
Table 5-17. USB Default Interface 0, Alternate Setting 1, Interrupt Endpoint Descriptor
Offset
Field
Description
Value
0
bLength
Length of this Endpoint Descriptor
07H
1
bDescriptorType
Descriptor Type = Endpoint
05H
2
bEndpointAddress
Endpoint Direction (1 is in) and Address = IN1
81H
3
bmAttributes
XFR Type = INT
03H
4
wMaxPacketSize (L)
Maximum Packet Size = 64 Bytes
40H
5
wMaxPacketSize (H)
Maximum Packet Size - High
00H
6
bInterval
Polling Interval in Milliseconds = 10 ms
0AH
Alternate setting 2 for the interrupt 1-IN increases the maximum packet size for the interrupt endpoint to 64.
Page 5-18
EZ-USB Technical Reference Manual v1.10
Table 5-18. USB Default Interface 0, Alternate Setting 2, Bulk Endpoint Descriptors
Offset
0
1
2
3
4
5
6
0
1
2
3
4
5
6
0
1
2
3
4
5
6
0
1
2
3
4
5
6
0
1
2
3
4
5
6
0
1
2
3
4
5
6
Field
bLength
bDescriptor Type
bEndpointAddress
bmAttributes
wMaxPacketSize (L)
wMaxPacketSize (H)
bInterval
bLength
bDescriptorType
bEndpointAddress
bmAttributes
wMaxPacketSize (L)
wMaxPacketSize (H)
bInterval
bLength
bDescriptorType
bEndpointAddress
bmAttributes
wMaxPacketSize (L)
wMaxPacketSize (H)
bInterval
bLength
bDescriptorType
bEndpointAddress
bmAttributes
wMaxPacketSize (L)
wMaxPacketSize (H)
bInterval
bLength
bDescriptorType
bEndpointAddress
bmAttributes
wMaxPacketSize (L)
wMaxPacketSize (H)
bInterval
bLength
bDescriptorType
bEndpointAddress
bmAttributes
wMaxPacketSize (L)
wMaxPacketSize (H)
bInterval
Description
Length of this Endpoint Descriptor
Descriptor Type = Endpoint
Endpoint Direction (1 is in) and Address = IN2
XFR Type = BULK
Maximum Packet Size = 64 Bytes
Maximum Packet Size - High
Polling Interval in Milliseconds (1 for iso)
Length of this Endpoint Descriptor
Descriptor Type = Endpoint
Endpoint Direction (1 is in) and Address = OUT2
XFR Type = BULK
Maximum Packet Size = 64 Bytes
Maximum Packet Size - High
Polling Interval in Milliseconds (1 for iso)
Length of this Endpoint Descriptor
Descriptor Type = Endpoint
Endpoint Direction (1 is in) and Address = IN4
XFR Type = BULK
Maximum Packet Size = 64 Bytes
Maximum Packet Size - High
Polling Interval in Milliseconds (1 for iso)
Length of this Endpoint Descriptor
Descriptor Type = Endpoint
Endpoint Direction (1 is in) and Address = OUT4
XFR Type = ISO
Maximum Packet Size = 64 Bytes
Maximum Packet Size - High
Polling Interval in Milliseconds (1 for iso)
Length of this Endpoint Descriptor
Descriptor Type = Endpoint
Endpoint Direction (1 is in) and Address = IN6
XFR Type = BULK
Maximum Packet Size = 64 Bytes
Maximum Packet Size - High
Polling Interval in Milliseconds (1 for iso)
Length of this Endpoint Descriptor
Descriptor Type = Endpoint
Endpoint Direction (1 is in) and Address = OUT6
XFR Type = BULK
Maximum Packet Size = 64 Bytes
Maximum Packet Size - High
Polling Interval in Milliseconds (1 for iso)
Value
07H
05H
82H
02H
40H
00H
00H
07H
05H
02H
02H
40H
00H
00H
07H
05H
84H
02H
40H
00H
00H
07H
05H
04H
02H
40H
00H
00H
07H
05H
86H
02H
40H
00H
00H
07H
05H
06H
02H
40H
00H
00H
The bulk endpoints for alternate setting 2 are identical to alternate setting 1.
Chapter 5. EZ-USB Enumeration and ReNumeration™
Page 5-19
EZ-USB Technical Reference Manual
Table 5-19. USB Default Interface 0, Alternate Setting 2, Isochronous Endpoint Descriptors
Offset
0
1
2
3
4
5
6
0
1
2
3
4
5
6
0
1
2
3
4
5
6
0
1
2
3
4
5
6
0
1
2
3
4
5
6
0
1
2
3
4
5
6
Field
bLength
bDescriptorType
bEndpointAddress
bmAttributes
wMaxPacketSize (L)
wMaxPacketSize (H)
bInterval
bLength
bDescriptorType
bEndpointAddress
bmAttributes
wMaxPacketSize (L)
wMaxPacketSize (H)
bInterval
bLength
bDescriptorType
bEndpointAddress
bmAttributes
wMaxPacketSize (L)
wMaxPacketSize (H)
bInterval
bLength
bDescriptorType
bEndpointAddress
bmAttributes
wMaxPacketSize (L)
wMaxPacketSize (H)
bInterval
bLength
bDescriptorType
bEndpointAddress
bmAttributes
wMaxPacketSize (L)
wMaxPacketSize (H)
bInterval
bLength
bDescriptorType
bEndpointAddress
bmAttributes
wMaxPacketSize (L)
wMaxPacketSize (H)
bInterval
Description
Length of this Endpoint Descriptor
Descriptor Type = Endpoint
Endpoint Direction (1 is in) and Address = IN8
XFR Type = ISO
Maximum Packet Size = 256 Bytes
Maximum Packet Size - High
Polling Interval in Milliseconds (1 for iso)
Length of this Endpoint Descriptor
Descriptor Type = Endpoint
Endpoint Direction (1 is in) and Address = OUT8
XFR Type = ISO
Maximum Packet Size = 256 Bytes
Maximum Packet Size - High
Polling Interval in Milliseconds (1 for iso)
Length of this Endpoint Descriptor
Descriptor Type = Endpoint
Endpoint Direction (1 is in) and Address = IN9
XFR Type = ISO
Maximum Packet Size = 16 Bytes
Maximum Packet Size - High
Polling Interval in Milliseconds (1 for iso)
Length of this Endpoint Descriptor
Descriptor Type = Endpoint
Endpoint Direction (1 is in) and Address = OUT9
XFR Type = ISO
Maximum Packet Size = 16 Bytes
Maximum Packet Size - High
Polling Interval in Milliseconds (1 for iso)
Length of this Endpoint Descriptor
Descriptor Type = Endpoint
Endpoint Direction (1 is in) and Address = IN10
XFR Type = ISO
Maximum Packet Size = 16 Bytes
Maximum Packet Size - High
Polling Interval in Milliseconds (1 for iso)
Length of this Endpoint Descriptor
Descriptor Type = Endpoint
Endpoint Direction (1 is in) and Address = OUT10
XFR Type = ISO
Maximum Packet Size = 16 Bytes
Maximum Packet Size - High
Polling Interval in Milliseconds (1 for iso)
Value
07H
05H
88H
01H
10H
01H
01H
07H
05H
08H
01H
00H
10H
01H
07H
05H
89H
01H
10H
00H
01H
07H
05H
09H
01H
10H
00H
01H
07H
05H
8AH
01H
10H
00H
01H
07H
05H
0AH
01H
10H
00H
01H
The only differences between alternate settings 1 and 2 are the maximum packet sizes for EP8IN
and EP8OUT. This is a high-bandwidth setting using 256 bytes each.
Page 5-20
EZ-USB Technical Reference Manual v1.10
Chapter 6
6.1
EZ-USB Bulk Transfers
Introduction
A E
I D N
N D D
R P
C
R
C
5
Token Packet
D
A
T
A
0
Payload
Data
C
R
C
1
6
Data Packet
A
C
K
H/S Pkt
A E
I D N
N D D
R P
C
R
C
5
D
A
T
A
1
Token Packet
Payload
Data
Data Packet
C
R
C
1
6
A
C
K
H/S Pkt
Figure 6-1. Two BULK Transfers, IN and OUT
EZ-USB provides sixteen endpoints for BULK, CONTROL, and INTERRUPT transfers, numbered
0-7 as shown in Table 6-1. This chapter describes BULK and INTERRUPT transfers. INTERRUPT transfers are a special case of BULK transfers. EZ-USB CONTROL endpoint zero is
described in Chapter 7, "EZ-USB Endpoint Zero."
Table 6-1. EZ-USB Bulk, Control, and Interrupt Endpoints
Endpoint
0
1
1
2
2
3
3
4
4
5
5
6
6
7
7
Chapter 6. EZ-USB Bulk Transfers
Direction
Bidir
IN
OUT
IN
OUT
IN
OUT
IN
OUT
IN
OUT
IN
OUT
IN
OUT
Type
Control
Bulk/Int
Bulk/Int
Bulk/Int
Bulk/Int
Bulk/Int
Bulk/Int
Bulk/Int
Bulk/Int
Bulk/Int
Bulk/Int
Bulk/Int
Bulk/Int
Bulk/Int
Bulk/Int
Size
64/64
64
64
64
64
64
64
64
64
64
64
64
64
64
64
Page 6-1
EZ-USB Technical Reference Manual
The USB specification allows maximum packet sizes of 8, 16, 32, or 64 bytes for bulk data, and 1
- 64 bytes for interrupt data. EZ-USB provides the maximum 64 bytes of buffer space for each of
its sixteen endpoints 0-7 IN and 0-7 OUT. Six of the bulk endpoints, 2-IN, 4-IN, 6-IN, 2-OUT, 4OUT, and 6-OUT may be paired with the next consecutively numbered endpoint to provide doublebuffering, which allows one data packet to be serviced by the 8051 while another is in transit over
USB. Six endpoint pairing bits (USBPAIR register) control double-buffering.
The 8051 sets fourteen endpoint valid bits (IN07VAL, OUT07VAL registers) at initialization time to
tell the EZ-USB core which endpoints are active. The default CONTROL endpoint zero is always
valid.
Bulk data appears in RAM. Each bulk endpoint has a reserved 64-byte RAM space, a 7-bit count
register, and a 2-bit control and status (CS) register. The 8051 can read one bit of the CS register
to determine endpoint busy, and write the other to force an endpoint STALL condition.
The 8051 should never read or write an endpoint buffer or byte count register while the endpoint’s
busy bit is set.
When an endpoint becomes ready for 8051 service, the EZ-USB core sets an interrupt request bit.
The EZ-USB vectored interrupt system separates the interrupt requests by endpoint to automatically transfer control to the ISR (Interrupt Service Routine) for the endpoint requiring service.
Chapter 9, "EZ-USB Interrupts" fully describes this mechanism.
Figure 6-2 illustrates the registers and bits associated with bulk transfers.
Page 6-2
EZ-USB Technical Reference Manual v1.10
Registers Associated with a Bulk IN endpoint
(EP2IN shown as example)
Initialization
IN07VAL
7
6
5
4
3
Data transfer
2
1
0
IN2BUF
Endpoint Valid (1=valid)
USBPAIR
o67
o45
o23
i67
i45
64 Byte
Endpoint
Buffer
i23
Endpoint Pairing (1=paired)
IN07IEN
7
6
5
4
3
2
1
0
IN2BC
Byte Count
Interrupt Enable (1=enabled)
Busy and Stall
Interrupt Control
IN2CS
B
S
IN07IRQ
Control & Status
7
6
5
4
3
2
1
0
Interrupt Request (write 1 to clear)
Registers Associated with a Bulk OUT endpoint
(EP4OUT shown as example)
Initialization
OUT07VAL
7
6
5
4
3
Data transfer
2
1
0
OUT4BUF
Endpoint Valid (1=valid)
USBPAIR
o67
o45
o23
i67
i45
64 Byte
Endpoint
Buffer
i23
Endpoint Pairing (1=paired)
OUT07IEN
7
6
5
4
3
2
1
0
OUT4BC
Byte Count
Interrupt Enable (1=enabled)
Busy and Stall
OUT4CS
Interrupt Control
B
Control & Status
S
OUT07IRQ
7
6
5
4
3
2
1
0
Interrupt Request (write 1 to clear)
Figure 6-2. Registers Associated with Bulk Endpoints
Chapter 6. EZ-USB Bulk Transfers
Page 6-3
EZ-USB Technical Reference Manual
Bulk IN Transfers
1
2
H
...
D
A
I D
N D
R
E
N
D
P
D
A
T
A
1
C
R
C
5
Token Packet
C
R
C
1
6
Payload
Data
Data Packet
...
5
H
A
I D
N D
R
E
N
D
P
C
R
C
5
Token Packet
4
5
H
H
D
A E
I D N
N D D
R P
A
C
K
C
R
C
5
Token Packet
H/S Pkt
(INnBC loaded)
4
3
..
.
N
A
K
H/S Pkt
EPnIN Interrupt, INnBSY=0
6
7
8
D
H
D
N
A
K
A
I D
N D
R
...
H/S Pkt
Load INnBC
E
N
D
P
C
R
C
5
Token Packet
H
D
A
T
A
0
Payload
Data
Data Packet
C
R
C
1
6
A
C
K
N ote: H =H ost, D =D evice ( EZ-U SB)
6.2
H/S Pkt
EPnIN Interrupt, INnBSY=0
Figure 6-3. Anatomy of a Bulk IN Transfer
USB bulk IN data travels from device to host. The host requests an IN transfer by issuing an IN
token to the EZ-USB core, which responds with data when it is ready. The 8051 indicates ready
by loading the endpoint’s byte count register. If the EZ-USB core receives an IN token for an endpoint that is not ready, it responds to the IN token with a NAK handshake.
In the bulk IN transfer illustrated in Figure 6-3, the 8051 has previously loaded an endpoint buffer
with a data packet, and then loaded the endpoint’s byte count register with the number of bytes in
the packet to arm the next IN transfer. This sets the endpoint’s BUSY Bit. The host issues an IN
token (1), to which the USB core responds by transmitting the data in the IN endpoint buffer (2).
When the host issues an ACK (3), indicating that the data has been received error-free, the USB
core clears the endpoint’s BUSY Bit and sets its interrupt request bit. This notifies the 8051 that
the endpoint buffer is empty. If this is a multi-packet transfer, the host then issues another IN token
to get the next packet.
If the second IN token (4) arrives before the 8051 has had time to fill the endpoint buffer, the EZ
USB core issues a NAK handshake, indicating busy (5). The host continues to send IN tokens (4)
and (7) until the data is ready. Eventually, the 8051 fills the endpoint buffer with data, and then
loads the endpoint’s byte count register (INnBC) with the number of bytes in the packet (6). Load-
Page 6-4
EZ-USB Technical Reference Manual v1.10
ing the byte count re-arms the given endpoint. When the next IN token arrives (7) the USB core
transfers the next data packet (8).
6.3
Interrupt Transfers
Interrupt transfers are handled just like bulk transfers.
The only difference between a bulk endpoint and an interrupt endpoint exists in the endpoint
descriptor, where the endpoint is identified as type interrupt, and a polling interval is specified. The
polling interval determines how often the USB host issues IN tokens to the interrupt endpoint.
6.4
EZ-USB Bulk IN Example
Suppose 220 bytes are to be transferred to the host using endpoint 2-IN. Further assume that
MaxPacketSize of 64 bytes for endpoint 2-IN has been reported to the host during enumeration.
Because the total transfer size exceeds the maximum packet size, the 8051 divides the 220-byte
transfer into four transfers of 64, 64, 64, and 28 bytes.
After loading the first 64 bytes into IN2BUF (at 0x7C00), the 8051 loads the byte count register
IN6BC with the value 64. Writing the byte count register instructs the EZ-USB core to respond to
the next host IN token by transmitting the 64 bytes in the buffer. Until the byte count register is
loaded to arm the IN transfer, any IN tokens issued by the host are answered by EZ-USB with NAK
(Not-Acknowledge) tokens, telling the USB host that the endpoint is not yet ready with data. The
host continues to issue IN tokens to endpoint 2-IN until data is ready for transfer—whereupon the
EZ-USB core replaces NAKs with valid data.
When the 8051 initiates an IN transfer by loading the endpoint’s byte count register, the EZ-USB
core sets a busy bit to instruct the 8051 to hold off loading IN2BUF until the USB transfer is finished. When the IN transfer is complete and successfully acknowledged, the EZ-USB core resets
the endpoint 2-IN busy bit and generates an endpoint 2-IN interrupt request. If the endpoint 2-IN
interrupt is enabled, program control automatically vectors to the data transfer routine for further
action (Autovectoring is enabled by setting AVEN=1; refer to Chapter 9, "EZ-USB Interrupts").
The 8051 now loads the next 64 bytes into IN2BUF and then loads the EPINBC register with 64 for
the next two transfers. For the last portion of the transfer, the 8051 loads the final 28 bytes into
IN2BUF, and loads IN2BC with 28. This completes the transfer.
Chapter 6. EZ-USB Bulk Transfers
Page 6-5
EZ-USB Technical Reference Manual
Initialization Note
When the EZ-USB chip comes out of RESET, or when the USB host issues a bus reset, the EZUSB core unarms IN endpoint 1-7 by setting their busy bits to 0. Any IN transfer requests are
NAKd until the 8051 loads the appropriate INxBC register(s). The endpoint valid bits are not
affected by an 8051 reset or a USB reset. Chapter 10, "EZ-USB Resets" describes the various
reset conditions in detail.
The EZ-USB core takes care of USB housekeeping chores such as handshake verification. When
an endpoint 2-IN interrupt occurs, the user is assured that the data loaded by the 8051 into the
endpoint buffer was received error-free by the host. The EZ-USB core automatically checks the
handshake information from the host and re-transmits the data if the host indicates an error by not
ACKing.
6.5
Bulk OUT Transfers
USB bulk OUT data travels from host to device. The host requests an OUT transfer by issuing an
OUT token to EZ-USB, followed by a packet of data. The EZ-USB core then responds with an
ACK, if it correctly received the data. If the endpoint buffer is not ready to accept data, the EZUSB core discards the host’s OUT data and returns a NAK token, indicating “not ready.” In
response, the host continues to send OUT tokens and data to the endpoint until the EZ-USB core
responds with an ACK.
Page 6-6
EZ-USB Technical Reference Manual v1.10
2
H
H
A E
O
D N
U
D D
T
R P
D
A
T
A
1
C
R
C
5
Payload
Data
(OUTnBC loaded,
OUTnBSY=1)
4
5
H
H
A E
O
D N
U
D D
T
R P
C
R
C
5
4
D
H
D
C
R
C
5
D
A
T
A
0
Payload
Data
C
R
C
1
6
Data Packet
N
A
K
H/S Pkt
EPnOUT Interrupt,
OUTnBSY=0
D
C
R
C
1
6
Payload
Data
Data Packet
Token Packet
6
H
Token Packet
H/S Pkt
6
D
A
T
A
0
5
A E
O
D N
U
D D
T
R P
A
C
K
Data Packet
Token Packet
..
.
C
R
C
1
6
3
N
A
K
H/S Pkt
7
8
9
H
H
A E
O
D N
U
D D
T
R P
C
R
C
5
Token Packet
Load OUTnBC (any value),
causes OUTnBSY=1
D
A
T
A
0
D
Payload
Data
Data Packet
C
R
C
1
6
A
C
K
..
.
N ote: H =H ost, D =D evice ( EZ-U SB)
...
1
H/S Pkt
EPnOUT Interrupt,
OUTnBSY=0
Figure 6-4. Anatomy of a Bulk OUT Transfer
Each EZ-USB bulk OUT endpoint has a byte count register, which serves two purposes. The 8051
reads the byte count register to determine how many bytes were received during the last OUT
transfer from the host. The 8051 writes the byte count register (with any value) to tell the EZ-USB
core that is has finished reading bytes from the buffer, making the buffer available to accept the
next OUT transfer. The OUT endpoints come up (after reset) armed, so the byte count register
writes are required only for OUT transfers after the first one.
In the bulk OUT transfer illustrated in Figure 6-4, the 8051 has previously loaded the endpoint’s
byte count register with any value to arm receipt of the next OUT transfer. Loading the byte count
register causes the EZ-USB core to set the OUT endpoint’s busy bit to 1, indicating that the 8051
should not use the endpoint’s buffer.
The host issues an OUT token (1), followed by a packet of data (2), which the USB core acknowledges, clears the endpoint’s busy bit and generates an interrupt request (3). This notifies the 8051
that the endpoint buffer contains valid USB data. The 8051 reads the endpoint’s byte count register
to find out how many bytes were sent in the packet, and transfers that many bytes out of the endpoint buffer.
In a multi-packet transfer, the host then issues another OUT token (4) along with the next data
packet (5). If the 8051 has not finished emptying the endpoint buffer, the EZ-USB FX host issues a
NAK, indicating busy (6). The data at (5) is shaded to indicate that the USB core discards it, and
does not over-write the data in the endpoint’s OUT buffer.
Chapter 6. EZ-USB Bulk Transfers
Page 6-7
EZ-USB Technical Reference Manual
The host continues to send OUT tokens (4, 5, and 6) that are greeted by NAKs until the buffer is
ready. Eventually, the 8051 empties the endpoint buffer data, and then loads the endpoint’s byte
count register (7) with any value to re-arm the USB core. Once armed and when the next OUT
token arrives (8) the USB core accepts the next data packet (9).
Initializing OUT Endpoints
When the EZ-USB chip comes out of reset, or when the USB host issues a bus reset, the EZUSB core arms OUT endpoints 1-7 by setting their busy bits to 1. Therefore, they are initially
ready to accept one OUT transfer from the host. Subsequent OUT transfers are NAKd until the
appropriate OUTnBC register is loaded to re-arm the endpoint.
The EZ-USB core takes care of USB housekeeping chores such as CRC checks and data toggle
PIDs. When an endpoint 6-OUT interrupt occurs and the busy bit is cleared, the user is assured
that the data in the endpoint buffer was received error-free from the host. The EZ-USB core automatically checks for errors and requests the host to re-transmit data if it detects any errors using
the built-in USB error checking mechanisms (CRC checks and data toggles).
6.6
Endpoint Pairing
Table 6-2. Endpoint Pairing Bits (in the USB PAIR Register)
5
4
3
2
1
0
Name
PR6OUT
PR4OUT
PR2OUT
PR6IN
PR4IN
PR2IN
Paired
6 OUT
4 OUT
2 OUT
6 IN
4 IN
2 IN
Endpoints
7 OUT
5 OUT
3 OUT
7 IN
5 IN
3 IN
Bit
The 8051 sets endpoint pairing bits to 1 to enable double-buffering of the bulk endpoint buffers.
With double buffering enabled, the 8051 can operate on one data packet while another is being
transferred over USB. The endpoint busy and interrupt request bits function identically, so the
8051 code requires little code modification to support double-buffering.
When an endpoint is paired, the 8051 uses only the even-numbered endpoint of the pair. The
8051 should not use the paired odd endpoint. For example, suppose it is desired to use endpoint
2-IN as a double-buffered endpoint. This pairs the IN2BUF and IN3BUF buffers, although the
8051 accesses the IN2BUF buffer only. The 8051 sets PR2IN=1 (in the USBPAIR register) to
enable pairing, sets IN2VAL=1 (in the IN07VAL register) to make the endpoint valid, and then uses
the IN2BUF buffer for all data transfers. The 8051 should not write the IN3VAL bit, enable IN3
interrupts, access the EP3IN buffer, or load the IN3BC byte count register.
Page 6-8
EZ-USB Technical Reference Manual v1.10
6.7
Paired IN Endpoint Status
INnBSY=1 indicates that both endpoint buffers are in use, and the 8051 should not load new IN
data into the endpoint buffer. When INnBSY=0, either one or both of the buffers is available for
loading by the 8051. The 8051 can keep an internal count that increments on EPnIN interrupts
and decrements on byte count loads to determine whether one or two buffers are free. Or, the
8051 can simply check for INnBSY=0 after loading a buffer (and loading its byte count register to
re-arm the endpoint) to determine if the other buffer is free.
Important Note
If an IN endpoint is paired and it is desired to clear the busy bit for that endpoint, do the following:
(a) write any value to the even endpoint’s byte count register twice, and (b) clear the busy bit for
both endpoints in the pair. This is the only code difference between paired and unpaired use of
an IN endpoint.
A bulk IN endpoint interrupt request is generated whenever a packet is successfully transmitted
over USB. The interrupt request is independent of the busy bit. If both buffers are filled and one is
sent, the busy bit transitions from 1-0; if one buffer is filled and then sent, the busy bit starts and
remains at 0. In either case an interrupt request is generated to tell the 8051 that a buffer is free.
6.8
Paired OUT Endpoint Status
OUTnBSY=1 indicates that both endpoint buffers are empty, and no data is available to the 8051.
When OUTnBSY=0, either one or both of the buffers holds USB OUT data. The 8051 can keep an
internal count that increments on EPnOUT interrupts and decrements on byte count loads to determine whether one or two buffers contain data. Or, the 8051 can simply check for OUTnBSY=0
after unloading a buffer (and loading its byte count register to re-arm the endpoint) to determine if
the other buffer contains data.
Chapter 6. EZ-USB Bulk Transfers
Page 6-9
EZ-USB Technical Reference Manual
6.9
Using Bulk Buffer Memory
Table 6-3. EZ-USB Endpoint 0-7 Buffer Addresses
Endpoint Buffer
Address
Mirrored
IN0BUF
7F00-7F3F
1F00-1F3F
OUT0BUF
7EC0-7EFF
1EC0-1EFF
IN1BUF
7E80-7EBF
1E80-1EBF
OUT1BUF
7E40-7E7F
1E40-1E7F
IN2BUF
7E00-7E3F
1E00-1E3F
OUT2BUF
7DC0-7DFF
1DC0-1DFF
IN3BUF
7D80-7DBF
1D80-1DBF
OUT3BUF
7D40-7D7F
1D40-1D7F
IN4BUF
7D00-7D3F
1D00-1D3F
OUT4BUF
7CC0-7CFF
1CC0-1CFF
IN5BUF
7C80-7CBF
1C80-1CBF
OUT5BUF
7C40-7C7F
1C40-1C7F
IN6BUF
7C00-7C3F
1C00-1C3F
OUT6BUF
7BC0-7BFF
1BC0-1BFF
IN7BUF
7B80-7BBF
1B80-1BBF
OUT7BUF
7B40-7B7F
1B40-1B7F
Table 6-3 shows the RAM locations for the sixteen 64-byte buffers for endpoints 0-7 IN and OUT.
These buffers are positioned at the bottom of the EZ-USB register space so that any buffers not
used for endpoints can be reclaimed as general purpose data RAM. The top of memory for the 8KB EZ-USB part is at 0x1B3F. However, if the endpoints are allocated in ascending order starting
with the lowest numbered endpoints, the higher numbered unused endpoints can effectively move
the top of memory to utilize the unused endpoint buffer RAM as data memory. For example, an
application that uses endpoint 1-IN, 2-IN/OUT (paired), 4-IN and 4-OUT can use 0x1B40-0x1CBF
as data memory. Chapter 3 gives full details of the EZ-USB memory map.
Note
Uploads or Downloads to unused bulk memory can be done only at the Mirrored (low) addresses
shown in Table 6-3.
Page 6-10
EZ-USB Technical Reference Manual v1.10
6.10
Data Toggle Control
The EZ-USB core automatically maintains the data toggle bits during bulk, control and interrupt
transfers. As explained in Chapter 1, "Introducing EZ-USB," the toggle bits are used to detect certain transmission errors so that erroneous data can be re-sent.
In certain circumstances, the host resets its data toggle to “DATA0”:
•
After sending a Clear_Feature: Endpoint Stall request to an endpoint.
•
After setting a new interface.
•
After selecting a new alternate setting.
In these cases, the 8051 can directly clear the data toggle for each of the bulk/interrupt/control
endpoints, using the TOGCTL register (Figure 6-5).
TOGCTL
Data Toggle Control
7FD7
b7
b6
b5
b4
b3
b2
b1
b0
Q
S
R
IO
0
EP2
EP1
EP0
R
R/W
R/W
R/W
R/W
R/W
R/W
R/W
x
x
x
x
x
x
x
x
Figure 6-5. Bulk Endpoint Toggle Control
The IO bit selects the endpoint direction (1=IN, 0=OUT), and the EP2-EP1-EP0 bits select the endpoint number. The Q bit, which is read-only, indicates the state of the data toggle for the selected
endpoint. Writing R=1 sets the data toggle to DATA0, and writing S=1 sets the data toggle to
DATA1.
Note
At the present writing, there appears to be no reason to set a data toggle to DATA1. The S bit is
provided for generality.
To clear an endpoint’s data toggle, the 8051 performs the following sequence:
•
Select the endpoint by writing the value 000D0EEE to the TOGCTL register, where D is
the direction and EEE is the endpoint number.
•
Clear the toggle bit by writing the value 001D0EEE to the TOGCTL register.
After step 1, the 8051 may read the state of the data toggle by reading the TOGCTL register
checking bit 7.
Chapter 6. EZ-USB Bulk Transfers
Page 6-11
EZ-USB Technical Reference Manual
6.11
Polled Bulk Transfer Example
The following code illustrates the EZ-USB registers used for a simple bulk transfer. In this example, 8051 register R1 keeps track of the number of endpoint 2-IN transfers and register R2 keeps
track of the number of endpoint 2-OUT transfers (mod-256). Every endpoint 2-IN transfer consists
of 64 bytes of a decrementing count, with the first byte replaced by the number of IN transfers and
the second byte replaced by the number of OUT transfers.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
start:
fill:
mov
mov
mov
mov
movx
inc
djnz
SP,#STACK-1
dptr,#IN2BUF
r7,#64
a,r7
@dptr,a
dptr
r7,rill
; set stack
; fill EP2IN buffer with
; decrementing counter
mov
mov
mov
mov
movx
r1,#0
r2,#0
dptr,#IN2BC
a,#40h
@dptr,a
;
;
;
;
;
mov
a,@dptr
jnb
mov
movx
jb
dptr,#IN2CS
; poll the EP2-IN Status
acc.1,serviceIN2
dptr,#OUT2CS
a,@dptr
acc.1,loop
; not busy--keep looping
inc
mov
movx
sjmp
r2
dptr,#OUT2BC
@dptr,a
loop
; OUT packet counter
; load byte count register to re-arm
; (any value)
inc
mov
mov
movx
inc
mov
movx
mov
mov
movx
sjmp
r1
dptr,3IN2BUF
a,r1
@dptr,a
dptr
a,r2
@dptr,a
dptr,#IN2BC
a,#40h
@dptr,a
loop
; IN packet counter
; update the first data byte
; in EP2IN buffer
;
;
loop:
movx
r1 is IN token counter
r2 is OUT token counter
Point to EP2 Byte Count register
64-byte transfer
arm the IN2 transfer
; EP2OUT is busy--keep looping
;
serviceOUT2:
;
serviceIN2:
; second byte in buffer
; get number of OUT packets
; point to EP2IN Byte Count Register
; load bc=64 to re-arm IN2
;
END
Figure 6-6. Example Code for a Simple (Polled) BULK Transfer
Page 6-12
EZ-USB Technical Reference Manual v1.10
The code at lines 2-7 fills the endpoint 2-IN buffer with 64 bytes of a decrementing count. Two 8bit counts are initialized to zero at lines 9 and 10. An endpoint 2-IN transfer is armed at lines 1113, which load the endpoint 2-IN byte count register IN2BC with 64. Then the program enters a
polling loop at lines 15-20, where it checks two flags for endpoint 2 servicing. Lines 15-17 check
the endpoint 2-IN busy bit in IN2CS bit 1. Lines 18-20 check the endpoint 2-OUT busy bit in
OUT2CS bit 1. When busy=1, the EZ-USB core is currently using the endpoint buffers and the
8051 should not access them. When busy=0, new data is ready for service by the 8051.
For both IN and OUT endpoints, the busy bit is set when the EZ-USB core is using the buffers, and
cleared by loading the endpoint’s byte count register. The byte count value is meaningful for IN
transfers because it tells the EZ-USB core how many bytes to transfer in response to the next IN
token. The 8051 can load any byte count OUT transfers, because only the act of loading the register is significant—loading OUTnBC arms the OUT transfer and sets the endpoint’s busy bit.
When an OUT packet arrives in OUT2BUF, the service routine at lines 22-26 increments R2, loads
the byte count (any value) into OUT2BC to re-arm the endpoint (lines 24-25), and jumps back to
the polling routine. This program does not use OUT2BUF data; it simply counts the number of
endpoint 2-OUT transfers.
When endpoint 2-IN is ready for the 8051 to load another packet into IN2BUF, the polling loop
jumps to the endpoint 2-IN service routine at lines 28-39. First, R1 is incremented (line 29). The
data pointer is set to IN2BUF at line 30, and register R1 is loaded into the first byte of the buffer
(lines 31-32). The data pointer is advanced to the second byte of IN2BUF at line 33, and register
R2 is loaded into the buffer (lines 34-35). Finally, the byte count 40H (64 decimal bytes) is loaded
into the byte count register IN2BC to arm the next IN transfer at lines 36-38, and the routine returns
the polling loop.
6.12
Enumeration Note
The code in this example is complete, and runs on the EZ-USB chip. You may be wondering about
the missing step, which reports the endpoint characteristics to the host during the enumeration
process. The reason this code runs without any enumeration code is that the EZ-USB chip comes
on as a fully-functional USB device with certain endpoints already configured and reported to the
host. Endpoint 2 is included in this default configuration. The full default configuration is described
in Chapter 5, "EZ-USB Enumeration and ReNumeration™."
6.13
Bulk Endpoint Interrupts
All USB interrupts activate the 8051 INT 2 interrupt. If enabled, INT2 interrupts cause the 8051 to
push the current program counter onto the stack, and then execute a jump to location 0x43, where
the programmer has inserted a jump instruction to the interrupt service routine (ISR). If the AVEN
(Autovector Enable) bit is set, the EZ-USB core inserts a special byte at location 0x45, which
directs the jump instruction to a table of jump instructions which transfer control the endpoint-specific ISR.
Chapter 6. EZ-USB Bulk Transfers
Page 6-13
EZ-USB Technical Reference Manual
Table 6-4. 8051 INT2 Interrupt Vector
Location
Op-Code
Instruction
0x43
02
LJMP
0x44
AddrH
0x45
AddrL*
* Replaced by EZ-USB Core if AVEN=1.
The byte inserted by the EZ-USB core at address 0x45 depends on which bulk endpoint requires
service. Table 6-5 shows all INT2 vectors, with the bulk endpoint vectors un-shaded. The shaded
interrupts apply to all the bulk endpoints.
Table 6-5. Byte Inserted by EZ-USB Core at Location 0x45 if AVEN=1
Interrupt
SUDAV
SOF
SUTOK
SUSPEND
USBRES
Reserved
EP0-IN
EP0-OUT
EP1-IN
EP1OUT
EP2IN
EP2OUT
EP3-IN
EP3-OUT
EP4-IN
EP4-OUT
EP5-IN
EP5-OUT
EP6-IN
EP6-OUT
EP7-IN
EP7-OUT
Inserted Byte at 0x45
0x00
0x04
0x08
0x0C
0x10
0x14
0x18
0X1C
0x20
0x24
0x28
0x2C
0x30
0x34
0x38
0x3C
0x40
0x44
0x48
0x4C
0x50
0x54
The vector values are four bytes apart. This allows the programmer to build a jump table to each
of the interrupt service routines. Note that the jump table must begin on a page (256 byte) boundary because the first vector starts at 00. If Autovectoring is not used (AVEN=0), the IVEC register
may be directly inspected to determine the USB interrupt source (see Section 9.11, "Autovector
Coding").
Each bulk endpoint interrupt has an associated interrupt enable bit (in IN07IEN and OUT07IEN),
and an interrupt request bit (in IN07IRQ and OUT07IRQ). The interrupt service routine. IRQ bits
are cleared by writing a “1.” Because all USB registers are accessed using “movx@dptr” instruc-
Page 6-14
EZ-USB Technical Reference Manual v1.10
tions, USB interrupt service routines must save and restore both data pointers, the DPS register,
and the accumulator before clearing interrupt request bits.
Note
Any USB ISR should clear the 8051 INT2 interrupt request bit before clearing any of the EZ-USB
endpoint IRQ bits, to avoid losing interrupts. Interrupts are discussed in more detail in Chapter 9,
"EZ-USB Interrupts."
Individual interrupt request bits are cleared by writing “1” to them to simplify code. For example,
to clear the endpoint 2-IN IRQ, simply write “0000100” to IN07IRQ. This will not disturb the other
interrupt request bits. Do not read the contents of IN07IRQ, logical-OR the contents with 01,
and write it back. This clears all other pending interrupts because you are writing “1”s to them.
6.14
Interrupt Bulk Transfer Example
This simple (but fully-functional) example illustrates the bulk transfer mechanism using interrupts.
In the example program, BULK endpoint 6 is used to loop data back to the host. Data sent by the
host over endpoint 2-OUT is sent back over endpoint 2-IN.
Chapter 6. EZ-USB Bulk Transfers
Page 6-15
EZ-USB Technical Reference Manual
1.
Set up the jump table.
CSEG
AT 300H
; any page boundary
ljmp
db
ljmp
db
ljmp
db
ljmp
db
ljmp
db
ljmp
db
ljmp
db
ljmp
db
ljmp
db
ljmp
db
ljmp
db
ljmp
db
ljmp
db
ljmp
db
ljmp
db
ljmp
db
ljmp
db
ljmp
db
ljmp
db
ljmp
db
ljmp
db
ljmp
db
SUDAV_ISR
0
SOF_ISR
0
SUTOK_ISR
0
SUSP_ISR
0
URES_ISR
0
SPARE_ISR
0
EP0IN_ISR
0
EP0OUT_ISR
0
EP1IN_ISR
0
EP1OUT_ISR
0
EP2IN_ISR
0
EP2OUT_ISR
0
EP3IN_ISR
0
EP3OUT_ISR
0
EP4IN_ISR
0
EP4OUT_ISR
0
EP5IN_ISR
0
EP5OUT_ISR
0
EP6IN_ISR
0
EP6OUT_ISR
0
EP7IN_ISR
0
EP7OUT_ISR
0
; SETUP Data Available
; make a 4-byte entry
; SOF
USB_Jump_Table:
; SETUP Data Loading
; Global Suspend
; USB Reset
; Used by this example
; Used by this example
Figure 6-7. Interrupt Jump Table
This table contains all of the USB interrupts, even though only the jumps for endpoint 2 are used
for the example. It is convenient to include this table in any USB application that uses interrupts.
Be sure to locate this table on a page boundary (xx00).
Page 6-16
EZ-USB Technical Reference Manual v1.10
2.
Write the INT2 interrupt vector.
; ----------------; Interrupt Vectors
; ----------------org
ljmp
43h
USB_Jump_Table
; int2 is the USB vector
; Autovector will replace byte 45
Figure 6-8. INT2 Interrupt Vector
3.
Write the interrupt service routine.
Put it anywhere in memory and the jump table in step 1 will automatically jump to it.
; ----------------------------; USB Interrupt Service Routine
; ----------------------------EP2OUT_ISR
push
dps
push
dpl
push
dph
push
dpl1
push
dph1
push
acc
mov
clr
mov
a,EXIF
acc.4
EXIF,a
mov
mov
movx
setb
dptr,#OUT07IRQ
a,#01000000b
@dptr,a
got_EP2_data
pop
pop
pop
pop
pop
pop
reti
acc
dph1
dpl1
dph
dpl
dps
; save both dptrs, dps, and acc
; clear USB IRQ (INT2)
; a “1” clears the IRQ bit
; clear OUT2 int request
; set my flag
; restore vital registers
Figure 6-9. Interrupt Service Routine (ISR) for Endpoint 2-OUT
In this example, the ISR simply sets the 8051 flag “got_EP2_data” to indicate to the background
program that the endpoint requires service. Note that both data pointers and the DPS (Data
Pointer Select) registers must be saved and restored in addition to the accumulator.
Chapter 6. EZ-USB Bulk Transfers
Page 6-17
EZ-USB Technical Reference Manual
4.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
Write the endpoint 2 transfer program.
loop:
jnb
clr
got_EP2_data,loop
got_EP2_data
; clear my flag
;
; The user sent bytes to OUT2 endpoint using the USB Control Panel.
; Find out how many bytes were sent.
;
mov
dptr,#OUT2BC
; point to OUT2 byte count register
movx
a,@dptr
; get the value
mov
r7,a
; stash the byte count
mov
r6,a
; save here also
;
; Transfer the bytes received on the OUT2 endpoint to the IN2 endpoint
; buffer. Number of bytes in r6 and r7.
;
mov
dptr,#OUT2BUF
; first data pointer points to EP2OUT buffer
inc
dps
; select the second data pointer
mov
dptr,#IN2BUF
; second data pointer points to EP2IN buffer
inc
dps
; back to first data pointer
transfer: movx
movx
get OUT byte
inc
dptr
; bump the pointer
inc
dps
; second data pointer
movx
@dptr,a
; put into IN buffer
inc
dptr
; bump the pointer
inc
dps
; first data pointer
djnz
r7,transfer
;
; Load the byte count into IN2BC. This arms in IN transfer
;
mov
dptr,#IN2BC
mov
a,r6
; get other saved copy of byte count
movx
@dptr,a
; this arms the IN transfer
;
; Load any byte count into OUT2BC. This arms the next OUT transfer.
;
mov
dptr,#OUT2BC
movx
@dptr,a
; use whatever is in acc
sjmp
loop
; start checking for another OUT2 packet
Figure 6-10. Background Program Transfers Endpoint 2-OUT Data to Endpoint 2-IN
The main program loop tests the “got_EP2_data” flag, waiting until it is set by the endpoint 2 OUT
interrupt service routine in Figure 6-10. This indicates that a new data packet has arrived in
OUT2BUF. Then the service routine is entered, where the flag is cleared in line 2. The number of
bytes received in OUT2BUF is retrieved from the OUT2BC register (Endpoint 2 Byte Count) and
saved in registers R6 and R7 in lines 7-10.
The dual data pointers are initialized to the source (OUT2BUF) and destination (IN2BUF) buffers
for the data transfer in lines 15-18. These labels represent the start of the 64-byte buffers for endpoint 2-OUT and endpoint 2-IN, respectively. Each byte is read from the OUT2BUF buffer and
written to the IN2BUF buffer in lines 19-25. The saved value of OUT2BC is used as a loop counter
in R7 to transfer the exact number of bytes that were received over endpoint 2-OUT.
Page 6-18
EZ-USB Technical Reference Manual v1.10
When the transfer is complete, the program loads the endpoint 2-IN byte count register IN2BC with
the number of loaded bytes (from R6) to arm the next endpoint 2-IN transfer in lines 29-31. Finally,
the 8051 loads any value into the endpoint 2 OUT byte count register OUT2BC to arm the next
OUT transfer in lines 35-36. Then the program loops back to check for more endpoint 2-OUT data.
5.
Initialize the endpoints and enable the interrupts.
start:
mov
SP,#STACK-1
; set stack
;
; Enable USB interrupts and Autovector
;
mov
dptr,#USBBAV
; enable Autovector
movx
a,@dptr,a
setb
acc.0
; AVEN bit is bit 0
movx
@dptr,a
;
mov
dptr,#OUT07IEN
; ‘EP0-7 OUT int enables’ register
;
mov
a,#01000000b
; set bit 6 for EP2OUT interrupt enable
movx
@dptr,a
; enable EP2OUT interrupt
;
; Enable INT2 and 8051 global interrupts
;
setb
ex2
; enable int2 (USB interrupt)
setb
EA
; enable 8051 interrupts
clr
got_EP2_data
; clear my flag
Figure 6-11. Initialization Routine
The initialization routine sets the stack pointer, and enables the EZ-USB Autovector by setting
USBBAV.0 to 1. Then it enables the endpoint 2-OUT interrupt, all USB interrupts (INT2), and the
8051 global interrupt (EA) and finally clears the flag indicating that endpoint 2-OUT requires service.
Once this structure is put into place, it is quite easy to service any or all of the bulk endpoints. To
add service for endpoint 2-IN, for example, simply write an endpoint 2-IN interrupt service routine
with starting address EP2IN_ISR (to match the address in the jump table in step 1), and add its
valid and interrupt enable bits to the “init” routine.
6.15
Enumeration Note
The code in this example is complete, and runs on the EZ-USB chip. You may be wondering about
the missing step, which reports the endpoint characteristics to the host during the enumeration
process. The reason this code runs without any enumeration code is that the EZ-USB chip comes
on as a fully-functional USB device with certain endpoints already configured and reported to the
host. Endpoint 2 is included in this default configuration. The full default configuration is described
in Chapter 5, "EZ-USB Enumeration and ReNumeration™."
Chapter 6. EZ-USB Bulk Transfers
Page 6-19
EZ-USB Technical Reference Manual
Portions of the above code are not necessary for the default configuration (such as setting the
endpoint valid bits) but the code is included to illustrate all of the EZ-USB registers used for bulk
transfers.
6.16
The Autopointer
Bulk endpoint data is available in 64-byte buffers in EZ-USB RAM. In some cases it is preferable
to access bulk data as a FIFO register rather than as a RAM. The EZ-USB core provides a special data pointer which automatically increments when data is transferred. Using this Autopointer,
the 8051 can access any contiguous block of internal EZ-USB RAM as a FIFO.
AUTOPTRH
Autopointer Address High
7FE3
b7
b6
b5
b4
b3
b2
b1
b0
A15
A14
A13
A12
A11
A10
A9
A8
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
x
x
x
x
x
x
x
x
AUTOPTRL
Autopointer Address Low
7FE4
b7
b6
b5
b4
b3
b2
b1
b0
A7
A6
A5
A4
A3
A2
A1
A0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
x
x
x
x
x
x
x
x
AUTODATA
Autopointer Data
7FE5
b7
b6
b5
b4
b3
b2
b1
b0
D7
D6
D5
D4
D3
D2
D1
D0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
x
x
x
x
x
x
x
x
Figure 6-12. Autopointer Registers
The 8051 first loads AUTOPTRH and AUTOPTRL with a RAM address (for example the address
of a bulk endpoint buffer). Then, as the 8051 reads or writes data to the data register AUTODATA,
the address is supplied by AUTOPTRH/L, which automatically increments after every read or write
to the AUTODATA register. The AUTOPTRH/L registers may be written or read at anytime. These
registers maintain the current pointer address, so the 8051 can read them to determine where the
next byte will be read or written.
Page 6-20
EZ-USB Technical Reference Manual v1.10
The 8051 code example in Figure 6-13 uses the Autopointer to transfer a block of eight data bytes
from the endpoint 4 OUT buffer to internal 8051 memory.
Init:
;
loop:
mov
mov
movx
mov
mov
movx
mov
mov
mov
dptr,#AUTOPTRH
a,#HIGH(OUT4BUF)
@dptr,a
dptr,#AUTOPTRL
a,#LOW(OUT4BUF)
@dptr,a
dptr,#AUTODATA
r0,#80H
r2,#8
movx
mov
inc
a,@dptr
@r0,a
r0
djnz
r2,loop
; High portion of OUT4BUF buffer
; Load OUTOPTRH
;
;
;
;
;
Low portion of OUT4BUF buffer address
Load AUTOPTRL
point to the ‘fifo’ register
store data in upper 128 bytes of 8051 RAM
loop counter
;
;
;
;
;
get a ‘fifo’ byte
store it
bump destination pointer
(NOTE: no ‘inc dptr’ required here)
do it eight times
Figure 6-13. Use of the Autopointer
As the comment in the penultimate line indicates, the Autopointer saves an “inc dptr” instruction
that would be necessary if one of the 8051 data pointers were used to access the OUT4BUF RAM
data. This improves the transfer time.
Note
Fastest bulk transfer speed in and out of EZ-USB bulk buffers is achieved when the Autopointer
is used in conjunction with the EZ-USB Fast Transfer mode.
As described in Chapter 8, "EZ-USB Isochronous Transfers," the EZ-USB core provides a method
for transferring data directly between an internal FIFO and external memory in two 8051 cycles
(333 ns). The fast transfer mode is active for bulk data when:
•
The 8051 sets FBLK=1 in the FASTXFR register, enabling fast bulk transfers,
•
The 8051 DPTR points to the AUTODATA register, and
•
The 8051 executes a “movx a,@dptr” or a “movx @dptr,a” instruction.
The 8051 code example in Figure 6-14 shows a transfer loop for moving 64 bytes of external FIFO
data into the endpoint 4-IN buffer. The FASTXFR register bits are explained in Chapter 8, "EZUSB Isochronous Transfers."
Chapter 6. EZ-USB Bulk Transfers
Page 6-21
EZ-USB Technical Reference Manual
Note
The Autopointer works only with internal program/data RAM. It does not work with memory outside the chip, or with internal RAM that is made available when ISODISAB=1. See Section 8.9.1,
"Disable ISO" for a description of the ISODISAB bit.
Init:
;
loop:
mov
mov
movx
mov
mov
movx
mov
mov
movx
mov
mov
dptr,#FASTXFR
a,#01000000b
@dptr,a
dptr,#AUTOPTRH
a,#HIGH(IN4BUF)
@dptr,a
dptr,#AUTOPTRL
a,#LOW(IN4BUF)
@dptr,a
dptr,#AUTODATA
r7,#8
; set up the fast BULK transfer mode
; FBLK=1, RPOL=0, RM1-0 = 00
; load the FASTXFR register
;
;
;
;
Low portion of IN4BUF buffer address
Load AUTOPTRH
point to the ‘fifo’ register
r7 is loop counter, 8 bytes per loop
movx
movx
movx
movx
movx
movx
movx
movx
djnz
@dptr,a
@dptr,a
@dptr,a
@dptr,a
@dptr,a
@dptr,a
@dptr,a
@dptr,a
r7,loop
;
;
;
;
;
;
;
;
;
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(3)
; High portion of IN4BUF
; Load AUTOPTRH
write IN ‘fifo’ using byte from external bus
again
again
again
again
again
again
again
do eight more, ‘r7’ times
Figure 6-14. 8051 Code to Transfer External Data to a Bulk IN Buffer
This transfer loop takes 19 cycles per loop times 8 passes, or 22 ms (152 cycles). A USB bulk
transfer of 64 bytes takes more that 42 ms (64*8*83 ns) of bus time to transfer the data bytes to or
from the host. This calculation neglects USB overhead time.
From this simple example, it is clear that by using the Autopointer and the EZ-USB Fast Transfer
mode, the 8051 can transfer data in and out of EZ-USB endpoint buffers significantly faster than
the USB can transfer it to and from the host. This means that the EZ-USB chip should never be a
speed bottleneck in a USB system. It also gives the 8051 ample time for other processing duties
between endpoint buffer loads.
The Autopointer can be used to quickly move data anywhere in RAM, not just the bulk endpoint
buffers. For example, it can be used to good effect in an application that calls for transferring a
block of data into RAM, processing the data, and then transferring the data to a bulk endpoint
buffer.
Page 6-22
EZ-USB Technical Reference Manual v1.10
Chapter 7
7.1
EZ-USB Endpoint Zero
Introduction
Endpoint Zero has special significance in a USB system. It is a CONTROL endpoint, and is
required by every USB device. Only CONTROL endpoints accept special SETUP tokens that the
host uses to signal transfers that deal with device control. The USB host sends a repertoire of
standard device requests over endpoint zero. These standard requests are fully defined in Chapter 9 of the USB Specification. This chapter describes how the EZ-USB chip handles endpoint
zero requests.
Because the EZ-USB chip can enumerate without firmware (see Chapter 5, "EZ-USB Enumeration
and ReNumeration™"), the EZ-USB core contains logic to perform enumeration on its own. This
hardware assist of endpoint zero operations is make available to the 8051, simplifying the code
required to service device requests. This chapter deals with 8051 control of endpoint zero
(ReNum=1, Chapter 5), and describes EZ-USB resources such as the Setup Data Pointer that simplify 8051 code that handles endpoint zero requests.
Endpoint zero is the only CONTROL endpoint in the EZ-USB chip. Although CONTROL endpoints
are bi-directional, the EZ-USB chip provides two 64-byte buffers, IN0BUF and OUT0BUF, which
the 8051 handles exactly like bulk endpoint buffers for the data stages of a CONTROL transfer. A
second 8-byte buffer, SETUPDAT, which is unique to endpoint zero, holds data that arrives in the
SETUP stage of a CONTROL transfer. This relieves the 8051 programmer of having to keep track
of the three CONTROL transfer phases—SETUP, DATA, and STATUS. The EZ-USB core also
generates separate interrupt requests for the various transfer phases, further simplifying code.
The IN0BUF and OUT0BUF buffers have two special properties that result from being used by
CONTROL endpoint zero:
•
Endpoints 0-IN and 0-OUT are always valid, so the valid bits (LSB of IN07VAL and
OUT07VAL registers) are permanently set to 1. Writing any value to these two bits has no
effect, and reading these bits always returns a 1.
•
Endpoint 0 cannot be paired with endpoint 1, so there is no pairing bit in the USBPAIR register for endpoint 0 or 1.
Chapter 7. EZ-USB Endpoint Zero
Page 7-1
EZ-USB Technical Reference Manual
7.2
Control Endpoint EP0
SETUP Stage
S
A E C
E
D N R
T
D D C
U
R P 5
P
Token Packet
D
A
T
A
0
C
R
C
1
6
8 bytes
Setup
Data
A
C
K
H/S Pkt
Data Packet
SUTOK Interrupt
Core sets HSNAK=1
SUDAV Interrupt
DATA Stage
A
I D
N D
R
E
N
D
P
C
R
C
5
D
A
T
A
1
C
R
C
1
6
Payload
Data
Data Packet
Token Packet
A
I D
N D
R
A
C
K
E
N
D
P
C
R
C
5
D
A
T
A
0
Data Packet
Token Packet
H/S Pkt
Payload
Data
EP0-IN Interrupt
C
R
C
1
6
A
C
K
H/S Pkt
EP0-IN Interrupt
STATUS Stage
A E
O
D N
U
D D
T
R P
C
R
C
5
Token Packet
D
A
T
A
1
Data
C
R
C
1
6
Pkt
S
N
Y
A
N
K
C
H/S Pkt
....
A E
O
D N
U
D D
T
R P
C
R
C
5
Token Packet
D
A
T
A
1
Data
C
A
R
C
C
K
1
6
Pkt H/S Pkt
8051 clears HSNAK bit (writes 1 to it)
or sets the STALL bit.
Figure 7-1. A USB Control Transfer (This One Has a Data Stage)
Endpoint zero accepts a special SETUP packet, which contains an 8-byte data structure that provides host information about the CONTROL transaction. CONTROL transfers include a final STATUS phase, constructed from standard PIDs (IN/OUT, DATA1, and ACK/NAK).
Some CONTROL transactions include all required data in their 8-byte SETUP Data packet. Other
CONTROL transactions require more OUT data than will fit into the eight bytes, or require IN data
from the device. These transactions use standard bulk-like transfers to move the data. Note in
Figure 7-1 that the “DATA Stage” looks exactly like a bulk transfer. As with BULK endpoints, the
endpoint zero byte count registers must be loaded to ACK the data transfer stage of a CONTROL
transfer.
Page 7-2
EZ-USB Technical Reference Manual v1.10
The STATUS stage consists of an empty data packet with the opposite direction of the data stage,
or an IN if there was no data stage. This empty data packet gives the device a chance to ACK or
NAK the entire CONTROL transfer. The 8051 writes a “1” to a bit call HSNAK (Handshake NAK) to
clear it and instruct the EZ-USB core to ACK the STATUS stage.
The HSNAK bit is used to hold off completing the CONTROL transfer until the device has had time
to respond to a request. For example, if the host issues a Set_Interface request, the 8051 performs various housekeeping chores such as adjusting internal modes and re-initializing endpoints.
During this time the host issues handshake (STATUS stage) packets to which the EZ-USB core
responds with NAKs, indicating “busy.” When the 8051 completes the desired operation, it sets
HSNAK=1 (by writing a “1” to the bit) to terminate the CONTROL transfer. This handshake prevents the host from attempting to use a partially configured interface.
To perform an endpoint stall for the DATA or STATUS stage of an endpoint zero transfer (the
SETUP stage can never stall), the 8051 must set both the STALL and HSNAK bits for endpoint
zero.
Some CONTROL transfers do not have a DATA stage. Therefore the 8051 code that processes
the SETUP data should check the length field in the SETUP data (in the 8-byte buffer at SETUPDAT) and arm endpoint zero for the DATA phase (by loading IN0BC or OUT0BC) only if the length
is non-zero.
Two 8051 interrupts provide notification that a SETUP packet has arrived, as shown in Figure 7-2.
SETUP Stage
S
A E C
E
D N R
T
D D C
U
R P 5
P
Token Packet
SUTOK
Interrupt
D
A
T
A
0
8 bytes
Setup
Data
Data Packet
C
R
C
1
6
A
C
K
SETUPDAT
8 RAM
bytes
H/S Pkt
SUDAV
Interrupt
Figure 7-2. The Two Interrupts Associated with EP0 CONTROL Transfers
The EZ-USB core sets the SUTOKIR bit (SETUP Token Interrupt Request) when the EZ-USB core
detects the SETUP token at the beginning of a CONTROL transfer. This interrupt is normally used
only for debug.
The EZ-USB core sets the SUDAVIR bit (Setup Data Available Interrupt Request) when the eight
bytes of SETUP data have been received error-free and transferred to eight EZ-USB registers
starting at SETUPDAT. The EZ-USB core takes care of any re-tries if it finds any errors in the
SETUP data. These two interrupt request bits are set by the EZ-USB core, and must be cleared
by firmware.
Chapter 7. EZ-USB Endpoint Zero
Page 7-3
EZ-USB Technical Reference Manual
An 8051 program responds to the SUDAV interrupt request by either directly inspecting the eight
bytes at SETUPDAT or by transferring them to a local buffer for further processing. Servicing the
SETUP data should be a high 8051 priority, since the USB Specification stipulates that CONTROL
transfers must always be accepted and never NAKd. It is therefore possible that a CONTROL
transfer could arrive while the 8051 is still servicing a previous one. In this case the previous
CONTROL transfer service should be aborted and the new one serviced. The SUTOK interrupt
gives advance warning that a new CONTROL transfer is about to over-write the eight SETUPDAT
bytes.
If the 8051 stalls endpoint zero (by setting the EP0STALL and HSNAK bits to 1), the EZ-USB core
automatically clears this stall bit when the next SETUP token arrives.
Like all EZ-USB interrupt requests, the SUTOKIR and SUDAVIR bits can be directly tested and
reset by the CPU (they are reset by writing a “1”). Thus, if the corresponding interrupt enable bits
are zero, the interrupt request conditions can still be directly polled.
Figure 7-3 shows the EZ-USB registers that deal with CONTROL transactions over EP0.
Registers Associated with Endpoint Zero
For handling SETUP transactions
Initialization
Data transfer
SETUPDAT
USBIEN
T
8 Bytes of
SETUP Data
D
Global Enable:
T=Setup Token SUTOKIE
D=Setup Data SUDAVIE
Interrupt Control
USBIRQ
T
Interrupt Request:
T=Setup Token SUTOKIR
D=Setup Data SUDAVIR
SUDPTRH
15
14
13
12
11
10
9
8
SUDPTRL
7
6
5
4
3
2
1
0
D
Figure 7-3. Registers Associated with EP0 Control Transfers
These registers augment those associated with normal bulk transfers over endpoint zero, which
are described in Chapter 6, "EZ-USB Bulk Transfers."
Two bits in the USBIEN (USB Interrupt Enable) register enable the SETUP Token (SUTOKIE) and
SETUP Data interrupts. The actual interrupt request bits are in the USBIRQ (USB Interrupt
Requests) register. They are called STOKIR (SETUP Token Interrupt Request) and SUDAVIR
(SETUP Data Interrupt Request).
Page 7-4
EZ-USB Technical Reference Manual v1.10
The EZ-USB core transfers the eight SETUP bytes into eight bytes of RAM at SETUPDAT. A 16bit pointer, SUDPTRH/L gives hardware assistance for handling CONTROL IN transfers, in particular, the USB Get_Descriptor requests described later in this chapter.
7.3
USB Requests
The Universal Serial Bus Specification Version 1.1, Chapter 9, "USB Device Framework" defines a
set of Standard Device Requests. When the 8051 is in control (ReNum=1), the EZ-USB core handles one of these requests (Set Address) directly, and relies on the 8051 to support the others.
The 8051 acts on device requests by decoding the eight bytes contained in the SETUP packet.
Table 7-1 shows the meaning of these eight bytes.
Table 7-1. The Eight Bytes in a USB SETUP Packet
Byte
Field
Meaning
0
bmRequestType
Request Type, Direction, and Recipient
1
bRequest
The actual request (see Table 7-2)
2
wValueL
Word-size value, varies according to bRequest
3
wValueH
4
wIndexL
5
wIndexH
6
wLengthL
7
wLengthH
Word-size field, varies according to bRequest
Number of bytes to transfer if there is a data phase
The Byte column in the previous table shows the byte offset from SETUPDAT. The Field column
shows the different bytes in the request, where the “bm” prefix means bit-map, “b” means byte, and
“w” means word (16 bits). Table 7-2 shows the different values defined for bRequest, and how the
8051 responds to each request. The remainder of this chapter describes each of the Table 7-2
requests in detail.
Note
Table 7-2 applies when ReNum=1, which signifies that the 8051, and not the EZ-USB core, handles device requests. Table 5-2 shows how the core handles each of these device requests
when ReNum=0, for example when the chip is first powered and the 8051 is not running.
Chapter 7. EZ-USB Endpoint Zero
Page 7-5
EZ-USB Technical Reference Manual
Table 7-2. How the 8051 Handles USB Device Requests (ReNum=1)
bRequest
Name
0x00
Get Status
0x01
Clear Feature
0x02
(reserved)
0x03
Set Feature
0x04
(reserved)
0x05
Set Address
0x06
Get Descriptor
0x07
Set Descriptor
0x08
Get Configuration
0x09
Set Configuration
0x0A
Get Interface
0x0B
Set Interface
0x0C
Sync Frame
Vendor Requests
0xA0 (Firmware Load)
0xA1 - 0xAF
All except 0xA0
Action
SUDAV Interrupt
SUDAV Interrupt
none
SUDAV Interrupt
none
Update FNADDR register
SUDAV Interrupt
SUDAV Interrupt
SUDAV Interrupt
SUDAV Interrupt
SUDAV Interrupt
SUDAV Interrupt
SUDAV Interrupt
8051 Response
Supply RemWU, SelfPwr or Stall bits
Clear RemWU, SelfPwr or Stall bits
Stall EP0
Set RemWU, SelfPwr or Stall bits
Stall EP0
none
Supply table data over EP0-IN
Application dependent
Send current configuration number
Change current configuration
Supply alternate setting No. from RAM
Change alternate setting No.
Supply a frame number over EP0-IN
Up/Download RAM
SUDAV Interrupt
SUDAV Interrupt
--Reserved by Cypress Semiconductor
Depends on application
In the ReNumerated condition (ReNum=1), the EZ-USB core passes all USB requests except Set
Address onto the 8051 via the SUDAV interrupt. This, in conjunction with the USB disconnect/
connect feature, allows a completely new and different USB device (yours) to be characterized by
the downloaded firmware.
The EZ-USB core implements one vendor-specific request, namely “Firmware Load,” 0xA0. (The
bRequest value of 0xA0 is valid only if byte 0 of the request, bmRequestType, is also “x10xxxxx,”
indicating a vendor-specific request.) The load request is valid at all times, so even after ReNumeration the load feature maybe used. If your application implements vendor-specific USB
requests, and you do not wish to use the Firmware Load feature, be sure to refrain from using the
bRequest value 0xA0 for your custom requests. The Firmware Load feature is fully described in
Chapter 5, "EZ-USB Enumeration and ReNumeration™."
Note
To avoid future incompatibilities, vendor requests A0-AF (hex) are reserved by Cypress Semiconductor.
7.3.1 Get Status
The USB Specification version 1.0 defines three USB status requests. A fourth request, to an
interface, is indicated in the spec as “reserved.” The four status requests are:
Page 7-6
EZ-USB Technical Reference Manual v1.10
•
Remote Wakeup (Device request)
•
Self-Powered (Device request)
•
Stall (Endpoint request)
•
Interface request (“reserved”)
The EZ-USB core activates the SUDAV interrupt request to tell the 8051 to decode the SETUP
packet and supply the appropriate status information.
SETUP Stage
S
A E C
E
D N R
T
D D C
U
R P 5
P
Token Packet
D
A
T
A
0
C
R
C
1
6
8 bytes
Setup
Data
Data Packet
SUTOK
Interrupt
A
C
K
SETUPDAT
8 RAM
bytes
H/S Pkt
SUDAV
Interrupt
DATA Stage
A
I D
N D
R
E
N
D
P
C
R
C
5
Token Packet
D
C
A
R
2
T
C
Bytes
A
1
1
6
Data Packet
A
C
K
H/S Pkt
IN0BUF
64-byte
Buffer
STATUS Stage
A E
O
D N
U
D D
T
R P
C
R
C
5
Token Packet
D C
A R
T C
A 1
1 6
Data Pkt
A
C
K
2
IN0BC
H/S Pkt
Figure 7-4. Data Flow for a Get_Status Request
As Figure 7-4 illustrates, the 8051 responds to the SUDAV interrupt by decoding the eight bytes
the EZ-USB core has copied into RAM at SETUPDAT. The 8051 answers a Get_Status request
(bRequest=0) by loading two bytes into the IN0BUF buffer and loading the byte count register
IN0BC with the value “2.” The EZ-USB core transmits these two bytes in response to an IN token.
Chapter 7. EZ-USB Endpoint Zero
Page 7-7
EZ-USB Technical Reference Manual
Finally, the 8051 clears the HSNAK bit (by writing “1” to it) to instruct the EZ-USB core to ACK the
status stage of the transfer.
The following tables show the eight SETUP bytes for Get_Status requests.
Table 7-3. Get Status-Device (Remote Wakeup and Self-Powered Bits)
Byte
Field
Value
Meaning
0
bmRequestType
0x80
IN, Device
1
bRequest
0x00
“Get Status”
2
wValueL
0x00
3
wValueH
0x00
4
wIndexL
0x00
5
wIndexH
0x00
6
wLengthL
0x02
7
wLengthH
0x00
8051 Response
Load two bytes into IN0BUF
Byte 0 : bit 0 = Self Powered bit
: bit 1 = Remote Wakeup
Byte 1 : zero
Two bytes
requested
Get_Status-Device queries the state of two bits, Remote Wakeup and Self-Powered. The Remote
Wakeup bit indicates whether or not the device is currently enabled to request remote wakeup.
Remote wakeup is explained in Chapter 11, "EZ-USB Power Management." The Self-Powered bit
indicates whether or not the device is self-powered (as opposed to USB bus-powered).
The 8051 returns these two bits by loading two bytes into IN0BUF, and then loading a byte count
of two into IN0BC.
Table 7-4. Get Status-Endpoint (Stall Bits)
Byte
0
Field
Value
Meaning
8051 Response
bmRequestType
0x82
IN, Endpoint
Load two bytes into IN0BUF
“Get Status”
Byte 0 : bit 0 = Stall bit for EP(n)
1
bRequest
0x00
2
wValueL
0x00
3
wValueH
0x00
4
wIndexL
EP
5
wIndexH
0x00
6
wLengthL
0x02
7
wLengthH
0x00
Byte 1 : zero
Endpoint Number
EP(n):
0x00-0x07: OUT0-OUT7
Two bytes requested
0x80-0x87: IN0-IN7
Each bulk endpoint (IN or OUT) has a STALL bit in its Control and Status register (bit 0). If the
CPU sets this bit, any requests to the endpoint return a STALL handshake rather than ACK or
NAK. The Get Status-Endpoint request returns the STALL state for the endpoint indicated in byte
4 of the request. Note that bit 7 of the endpoint number EP (byte 4) specifies direction.
Endpoint zero is a CONTROL endpoint, which by USB definition is bi-directional. Therefore, it has
only one stall bit.
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EZ-USB Technical Reference Manual v1.10
About STALL
The USB STALL handshake indicates that something unexpected has happened. For instance,
if the host requests an invalid alternate setting or attempts to send data to a non-existent endpoint, the device responds with a STALL handshake over endpoint zero instead of ACK or NAK.
Stalls are defined for all endpoint types except ISOCHRONOUS, which do not employ handshakes. Every EZ-USB bulk endpoint has its own stall bit. The 8051 sets the stall condition for
an endpoint by setting the stall bit in the endpoint’s CS register. The host tells the 8051 to set or
clear the stall condition for an endpoint using the Set_Feature/Stall and Clear_Feature/Stall
requests.
An example of the 8051 setting a stall bit would be in a routine that handles endpoint zero device
requests. If an undefined or non-supported request is decoded, the 8051 should stall EP0. (EP0
has a single stall bit because it is a bi-directional endpoint.)
Once the 8051 stalls an endpoint, it should not remove the stall until the host issues a
Clear_Feature/Stall request. An exception to this rule is endpoint 0, which reports a stall condition only for the current transaction, and then automatically clears the stall condition. This prevents endpoint 0, the default CONTROL endpoint, from locking out device requests.
Table 7-5. Get Status-Interface
Byte
Field
Value
Meaning
8051 Response
0
bmRequestType
0x81
IN, Endpoint
Load two bytes into IN0BUF
1
bRequest
0x00
“Get Status”
Byte 0 : zero
2
wValueL
0x00
3
wValueH
0x00
4
wIndexL
0x00
5
wIndexH
0x00
6
wLengthL
0x02
7
wLengthH
0x00
Byte 1 : zero
Two bytes
requested
Get_Status/Interface is easy: the 8051 returns two zero bytes through IN0BUF and clears the
HSNAK bit. The requested bytes are shown as “Reserved (Reset to zero)” in the USB Specification
Chapter 7. EZ-USB Endpoint Zero
Page 7-9
EZ-USB Technical Reference Manual
7.3.2 Set Feature
Set Feature is used to enable remote wakeup or stall an endpoint. No data stage is required.
Table 7-6. Set Feature-Device (Set Remote Wakeup Bit)
Byte
Field
Value
Meaning
0
bmRequestType
0x00
OUT, Device
1
bRequest
0x03
“Set Feature”
2
wValueL
0x01
Feature Selector:
Remote Wakeup
3
wValueH
0x00
4
wIndexL
0x00
5
wIndexH
0x00
6
wLengthL
0x00
7
wLengthH
0x00
8051 Response
Set the Remote Wakeup bit
The only Set_Feature/Device request presently defined in the USB specification is to set the
remote wakeup bit. This is the same bit reported back to the host as a result of a Get StatusDevice request (Table 7-3). The host uses this bit to enable or disable remote wakeup by the
device.
Table 7-7. Set Feature-Endpoint (Stall)
Byte
Field
0
bmRequestType
1
bRequest
2
wValueL
3
4
5
6
7
wValueH
wIndexL
wIndexH
wLengthL
wLengthH
Value
0x02
0x03
0x00
Meaning
8051 Response
Set the STALL bit for the
OUT, Endpoint
indicated endpoint:
“Set Feature”
Feature Selector:
STALL
0x00
EP
0x00
0x00
0x00
EP(n):
0x00-0x07: OUT0-OUT7
0x80-0x87: IN0-IN7
The only Set_Feature/Endpoint request presently defined in the USB Specification is to stall an
endpoint. The 8051 should respond to this request by setting the stall bit in the Control and Status
register for the indicated endpoint EP (byte 4 of the request). The 8051 can either stall an endpoint on its own, or in response to the device request. Endpoint stalls are cleared by the host
Clear_Feature/Stall request.
The 8051 should respond to the Set_Feature/Stall request by performing the following steps:
1. Set the stall bit in the indicated endpoint’s CS register.
2. Reset the data toggle for the indicated endpoint.
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EZ-USB Technical Reference Manual v1.10
3. For an IN endpoint, clear the busy bit in the indicated endpoint’s CS register.
4. For an OUT endpoint, load any value into the endpoint’s byte count register.
5. Clear the HSNAK bit in the EP0CS register (by writing 1 to it) to terminate the Set_Feature/
Stall CONTROL transfer.
Steps 3 and 4 restore the stalled endpoint to its default condition, ready to send or accept data
after the stall condition is removed by the host (using a Clear_Feature/Stall request). These steps
are also required when the host sends a Set_Interface request.
Data Toggles
The EZ-USB core automatically maintains the endpoint toggle bits to ensure data integrity for
USB transfers. The 8051 should directly manipulate these bits only for a very limited set of circumstances:
•
Set_Feature/Stall
•
Set_Configuration
•
Set_Interface
7.3.3 Clear Feature
Clear Feature is used to disable remote wakeup or to clear a stalled endpoint.
Table 7-8. Clear Feature-Device (Clear Remote Wakeup Bit)
Byte
Field
Value
Meaning
bmRequestType
0x00
1
bRequest
0x01
“Clear Feature”
2
wValueL
0x01
Feature Selector:
Remote Wakeup
3
wValueH
0x00
4
wIndexL
0x00
5
wIndexH
0x00
6
wLengthL
0x00
7
wLengthH
0x00
0
Chapter 7. EZ-USB Endpoint Zero
OUT, Device
8051 Response
Clear the remote wakeup bit
Page 7-11
EZ-USB Technical Reference Manual
Table 7-9. Clear Feature-Endpoint (Clear Stall)
Byte
Field
Value
Meaning
8051 Response
bmRequestType
0x02
OUT, Endpoint
Clear the STALL bit for the
1
bRequest
0x01
“Clear Feature”
indicated endpoint:
2
wValueL
0x00
Feature Selector:
STALL
3
wValueH
0x00
4
wIndexL
EP
5
wIndexH
0x00
0x00-0x07: OUT0-OUT7
6
wLengthL
0x00
0x80-0x87: IN0-IN7
7
wLengthH
0x00
0
EP(n):
If the USB device supports remote wakeup (as reported in its descriptor table when the device is
enumerated), the Clear_Feature/Remote Wakeup request disables the wakeup capability.
The Clear_Feature/Stall removes the stall condition from an endpoint. The 8051 should respond
by clearing the stall bit in the indicated endpoint’s CS register.
7.3.4 Get Descriptor
During enumeration, the host queries a USB device to learn its capabilities and requirements
using Get_Descriptor requests. Using tables of descriptors, the device sends back (over EP0-IN)
such information as what device driver to load, how many endpoints it has, its different configurations, alternate settings it may use, and informative text strings about the device.
The EZ-USB core provides a special Setup Data Pointer to simplify 8051 service for
Get_Descriptor requests. The 8051 loads this 16-bit pointer with the beginning address of the
requested descriptor, clears the HSNAK bit (by writing “1” to it), and the EZ-USB core does the
rest.
Page 7-12
EZ-USB Technical Reference Manual v1.10
SETUP Stage
S
A E C
E
D N R
T
D D C
U
R P 5
P
Token Packet
D
A
T
A
0
8 bytes
Setup
Data
C
R
C
1
6
Data Packet
A
C
K
SETUPDAT
8 RAM
bytes
H/S Pkt
SUDAV Interrupt
DATA Stage
A
I D
N D
R
E
N
D
P
C
R
C
5
Token Packet
D
A
T
A
1
Payload
Data
Data Packet
C
R
C
1
6
A
C
K
H/S Pkt
A
I D
N D
R
E
N
D
P
C
R
C
5
Token Packet
EP0IN
Interrupt
STATUS Stage
A E
O
D N
U
D D
T
R P
C
R
C
5
Token Packet
D C
A R
A
T C
C
A 1
K
1 6
Data Pkt H/S Pkt
D
A
T
A
0
C
R
C
1
6
Payload
Data
Data Packet
A
C
K
H/S Pkt
EP0IN
Interrupt
SUDPTRH/L
64 bytes
27 bytes
Figure 7-5. Using the Setup Data Pointer (SUDPTR) for Get_Descriptor Requests
Figure 7-5 illustrates use of the Setup Data Pointer. This pointer is implemented as two registers,
SUDPTRH and SUDPTRL. Most Get_Descriptor requests involve transferring more data than will
fit into one packet. In the Figure 7-5 example, the descriptor data consists of 91 bytes.
The CONTROL transaction starts in the usual way, with the EZ-USB core transferring the eight
bytes in the SETUP packet into RAM at SETUPDAT and activating the SUDAV interrupt request.
The 8051 decodes the Get_Descriptor request, and responds by clearing the HSNAK bit (by writing “1” to it), and then loading the SUDPTR registers with the address of the requested descriptor.
Loading the SUDPTRL register causes the EZ-USB core to automatically respond to two IN transfers with 64 bytes and 27 bytes of data using SUDPTR as a base address, and then to respond to
(ACK) the STATUS stage.
The usual endpoint zero interrupts, SUDAV and EP0IN, remain active during this automated transfer. The 8051 normally disables these interrupts because the transfer requires no 8051 intervention.
Chapter 7. EZ-USB Endpoint Zero
Page 7-13
EZ-USB Technical Reference Manual
Three types of descriptors are defined: Device, Configuration, and String.
7.3.4.1 Get Descriptor-Device
Table 7-10. Get Descriptor-Device
Byte
Field
Value
Meaning
8051 Response
bmRequestType
0x80
IN, Device
Set SUDPTR H-L to start of
1
bRequest
0x06
“Get_Descriptor”
Device Descriptor table in RAM
2
wValueL
0x00
3
wValueH
0x01
4
wIndexL
0x00
5
wIndexH
0x00
6
wLengthL
LenL
7
wLengthH
LenH
0
Descriptor Type:
Device
As illustrated in Figure 7-5, the 8051 loads the 2-byte SUDPTR with the starting address of the
Device Descriptor table. When SUDPTRL is loaded, the EZ-USB core performs the following
operations:
1. Reads the requested number of bytes for the transfer from bytes 6 and 7 of the SETUP packet
(LenL and LenH in Table 7-11).
2. Reads the requested string’s descriptor to determine the actual string length.
3. Sends the smaller of (a) the requested number of bytes or (b) the actual number of bytes in
the string, over IN0BUF using the Setup Data Pointer as a data table index. This constitutes
the second phase of the three-phase CONTROL transfer. The core Packetizes the data into
multiple data transfers as necessary.
4. Automatically checks for errors and re-transmits data packets if necessary.
5. Responds to the third (handshake) phase of the CONTROL transfer to terminate the operation.
The Setup Data Pointer can be used for any Get_Descriptor request; for example,
Get_Descriptor-String. It can also be used for vendor-specific requests (that you define), as long
as bytes 6-7 contain the number of bytes in the transfer (for step 1).
It is possible for the 8051 to do manual CONTROL transfers, directly loading the IN0BUF buffer
with the various packets and keeping track of which SETUP phase is in effect. This would be a
good USB training exercise, but not necessary due to the hardware support built into the EZ-USB
core for CONTROL transfers.
For DATA stage transfers of fewer than 64 bytes, moving the data into the IN0BUF buffer and then
loading the EP0INBC register with the byte count would be equivalent to loading the Setup Data
Pointer. However, this would waste 8051 overhead because the Setup Data Pointer requires no
byte transfers into the IN0BUF buffer.
Page 7-14
EZ-USB Technical Reference Manual v1.10
7.3.4.2 Get Descriptor-Configuration
Table 7-11. Get Descriptor-Configuration
Byte
Field
Value
Meaning
8051 Response
IN, Device
Set SUDPTR H-L to start of
0x06
“Get_Descriptor”
requested Configuration
CFG
Config Number
Descriptor table in RAM
wValueH
0x02
Descriptor Type:
Configuration
4
wIndexL
0x00
5
wIndexH
0x00
6
wLengthL
LenL
7
wLengthH
LenH
0
bmRequestType
0x80
1
bRequest
2
wValueL
3
7.3.4.3 Get Descriptor-String
Table 7-12. Get Descriptor-String
Byte
Field
Value
Meaning
8051 Response
bmRequestType
0x80
IN, Device
Set SUDPTR H-L to start of
1
bRequest
0x06
“Get_Descriptor”
requested String Descriptor
2
wValueL
STR
String Number
table in RAM
0
3
wValueH
0x03
Descriptor Type: String
4
wIndexL
0x00
(Language ID L)
5
wIndexH
0x00
(Language ID H)
6
wLengthL
LenL
7
wLengthH
LenH
Configuration and string descriptors are handled similarly to device descriptors. The 8051 firmware reads byte 2 of the SETUP data to determine which configuration or string is being
requested, loads the corresponding table pointer into SUDPTRH-L, and the EZ-USB core does the
rest.
Chapter 7. EZ-USB Endpoint Zero
Page 7-15
EZ-USB Technical Reference Manual
7.3.5 Set Descriptor
Table 7-13. Set Descriptor-Device
Byte
Field
Value
Meaning
8051 Response
0
bmRequestType
0x00
OUT, Device
Read device descriptor data
over
1
bRequest
0x07
“Set_Descriptor”
OUT0BUF
2
wValueL
0x00
3
wValueH
0x01
4
wIndexL
0x00
5
wIndexH
0x00
6
wLengthL
LenL
7
wLengthH
LenH
Descriptor Type: Device
Table 7-14. Set Descriptor-Configuration
Byte
Field
Value
Meaning
8051 Response
0
bmRequestType
0x00
OUT, Device
Read configuration descriptor
1
bRequest
0x07
“Set_Descriptor”
data over OUT0BUF
2
wValueL
0x00
3
wValueH
0x02
4
wIndexL
0x00
5
wIndexH
0x00
6
wLengthL
LenL
7
wLengthH
LenH
Descriptor Type: Configuration
Table 7-15. Set Descriptor-String
Byte
Field
Value
bmRequestType
0x00
1
bRequest
2
wValueL
3
4
5
6
7
0
Page 7-16
Meaning
8051 Response
IN, Device
Read string descriptor data over
0x07
“Get_Descriptor”
OUT0BUF
0x00
Config Number
wValueH
0x03
Descriptor Type: String
wIndexL
0x00
(Language ID L)
wIndexH
0x00
(Language ID H)
wLengthL
LenL
wLengthH
LenH
EZ-USB Technical Reference Manual v1.10
The 8051 handles Set_Descriptor requests by clearing the HSNAK bit (by writing “1” to it), then
reading descriptor data directly from the OUT0BUF buffer. The EZ-USB core keeps track of the
number of byes transferred from the host into OUT0BUF, and compares this number with the
length field in bytes 6 and 7. When the proper number of bytes has been transferred, the EZ-USB
core automatically responds to the status phase, which is the third and final stage of the CONTROL transfer.
Note
The 8051 controls the flow of data in the Data Stage of a Control Transfer. After the 8051 processes each OUT packet, it loads any value into the OUT endpoint’s byte count register to re-arm
the endpoint.
Configurations, Interfaces, and Alternate Settings
Configurations, Interfaces, and Alternate Settings
Device
A USB device has one or more configuration. Only one configuration is active at any
time.
A configuration has one or more interface, all
of which are concurrently active. Multiple
interfaces allow different host-side device
drivers to be associated with different portions of a USB device.
Each interface has one or more alternate
setting. Each alternate setting has a collection of one or more endpoints.
Config 1
High Power
Interface 0
CDROM
control
Alt Setting
0
Interface 1
audio
Config 2
Low Power
Interface 3
data
storage
Interface 2
video
Alt Setting
1
Alt Setting
3
ep
ep
O ne at a tim e
Concurrent
O ne at a tim e
ep
This structure is a software model; the EZ-USB core takes no action when these settings change.
However, the 8051 must re-initialize endpoints when the host changes configurations or interfaces alternate settings.
As far as 8051 firmware is concerned, a configuration is simply a byte variable that indicates the
current setting.
The host issues a Set_Configuration request to select a configuration, and a Get_Configuration
request to determine the current configuration.
Chapter 7. EZ-USB Endpoint Zero
Page 7-17
EZ-USB Technical Reference Manual
7.3.6 Set Configuration
Table 7-16. Set Configuration
Byte
Field
Value
Meaning
8051 Response
Read and stash byte 2,
change
0
bmRequestType
0x00
OUT, Device
1
bRequest
0x09
“Set_Configuration” configurations in firmware
Config Number
2
wValueL
CFG
3
wValueH
0x00
4
wIndexL
0x00
5
wIndexH
0x00
6
wLengthL
0x00
7
wLengthH
0x00
When the host issues the Set_Configuration request, the 8051 saves the configuration number
(byte 2 in Table Table 7-16), performs any internal operations necessary to support the configuration, and finally clears the HSNAK bit (by writing “1” to it) to terminate the Set_Configuration CONTROL transfer.
Note
After setting a configuration, the host issues Set_Interface commands to set up the various interfaces contained in the configuration.
7.3.7 Get Configuration
Table 7-17. Get Configuration
Byte
Page 7-18
Field
Value
Meaning
8051 Response
0
bmRequestType
0x80
IN, Device
Send CFG over IN0BUF after
1
bRequest
0x08
“Get_Configuration”
re-configuring
2
wValueL
0x00
3
wValueH
0x00
4
wIndexL
0x00
5
wIndexH
0x00
6
wLengthL
1
LenL
7
wLengthH
0
LenH
EZ-USB Technical Reference Manual v1.10
The 8051 returns the current configuration number. It loads the configuration number into EP0IN,
loads a byte count of one into EP0INBC, and finally clears the HSHAK bit (by writing “1” to it) to terminate the Set_Configuration CONTROL transfer.
7.3.8 Set Interface
This confusingly named USB command actually sets and reads back alternate settings for a specified interface.
USB devices can have multiple concurrent interfaces. For example a device may have an audio
system that supports different sample rates, and a graphic control panel that supports different languages. Each interface has a collection of endpoints. Except for endpoint 0, which each interface
uses for device control, endpoints may not be shared between interfaces.
Interfaces may report alternate settings in their descriptors. For example, the audio interface may
have setting 0, 1, and 2 for 8-KHz, 22-KHz, and 44-KHz sample rates, and the panel interface may
have settings 0 and 1 for English and Spanish. The Set/Get_Interface requests select between
the various alternate settings in an interface.
Table 7-18. Set Interface (Actually, Set Alternate Setting AS for Interface IF)
Byte
Field
Value
Meaning
8051 Response
0
bmRequestType
0x00
OUT, Device
Read and stash byte 2 (AS) for
1
bRequest
0x0B
“Set_Interface”
Interface IF, change setting for
2
wValueL
AS
Alt Setting Number
Interface IF in firmware
3
wValueH
0x00
4
wIndexL
IF
5
wIndexH
0x00
6
wLengthL
0x00
7
wLengthH
0x00
For this interface
The 8051 should respond to a Set_Interface request by performing the following steps:
•
Perform the internal operation requested (such as adjusting a sampling rate).
•
Reset the data toggles for every endpoint in the interface.
•
For an IN endpoint, clear the busy bit for every endpoint in the interface.
•
For an OUT endpoint, load any value into the byte count register for every endpoint in the
interface.
•
Clear the HSNAK bit (by writing “1” to it) to terminate the Set_Feature/Stall CONTROL
transfer.
Chapter 7. EZ-USB Endpoint Zero
Page 7-19
EZ-USB Technical Reference Manual
7.3.9 Get Interface
Table 7-19. Get Interface (Actually, Get Alternate Setting AS for interface IF)
Byte
Field
Value
Meaning
8051 Response
0
bmRequestType
0x81
IN, Device
Send AS for Interface IF over
1
bRequest
0x0A
“Get_Interface”
OUT0BUF (1 byte)
2
wValueL
0x00
3
wValueH
0x00
4
wIndexL
IF
5
wIndexH
0x00
6
wLengthL
1
LenL
7
wLengthH
0
LenH
For this interface
The 8051 simply returns the alternate setting for the requested interface IF, and clears the HSNAK
bit by writing “1” to it.
7.3.10 Set Address
When a USB device is first plugged in, it responds to device address 0 until the host assigns it a
unique address using the Set_Address request. The EZ-USB core copies this device address into
the FNADDR (Function Address) register, and subsequently responds only to requests to this
address. This address is in effect until the USB device is unplugged, the host issues a USB
Reset, or the host powers down.
The FNADDR register can be read, but not written by the 8051. Whenever the EZ-USB core
ReNumerates, it automatically resets the FNADDR to zero allowing the device to come back as
new.
An 8051 program does not need to know the device address, because the EZ-USB core automatically responds only to the host-assigned FNADDR value. The EZ-USB core makes it readable by
the 8051 for debug/diagnostic purposes.
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EZ-USB Technical Reference Manual v1.10
7.3.11 Sync Frame
Table 7-20. Sync Frame
Byte
Field
Value
Meaning
8051 Response
0
bmRequestType
0x82
IN, Endpoint
Send a frame number over
1
bRequest
0x0C
“Sync_Frame”
IN0BUF to synchronize endpoint
2
wValueL
0x00
3
wValueH
0x00
EP
4
wIndexL
EP
5
wIndexH
0x00
Endpoint number
6
wLengthL
2
LenL
0x08-0x0F: OUT8-OUT15
7
wLengthH
0
LenH
0x88-0x8F: IN8-IN15
EP(n):
The Sync_Frame request is used to establish a marker in time so the host and USB device can
synchronize multi-frame transfers over isochronous endpoints.
Suppose an isochronous transmission consists of a repeating sequence of five 300 byte packets
transmitted from host to device over EP8-OUT. Both host and device maintain sequence counters
that count repeatedly from 1 to 5 to keep track of the packets inside a transmission. To start up in
sync, both host and device need to reset their counts to 1 at the same time (in the same frame).
To get in sync, the host issues the Sync_Frame request with EP=EP-OUT (byte 4). The 8051 firmware responds by loading IN0BUF with a two-byte frame count for some future time; for example,
the current frame plus 20. This marks frame “current+20” as the sync frame, during which both
sides will initialize their sequence counters to 1. The 8051 reads the current frame count in the
USBFRAMEL and USBFRAMEH registers.
Multiple isochronous endpoints can be synchronized in this manner. The 8051 keeps separate
internal sequence counts for each endpoint.
About USB Frames
The USB host issues a SOF (Start Of Frame) packet once every millisecond. Every SOF packet
contains an 11-bit (mod-2048) frame number. The 8051 services all isochronous transfers at
SOF time, using a single SOF interrupt request and vector. If the EZ-USB core detects a missing
SOF packet, it uses an internal counter to generate the SOF interrupt.
Chapter 7. EZ-USB Endpoint Zero
Page 7-21
EZ-USB Technical Reference Manual
7.3.12 Firmware Load
The USB endpoint zero protocol provides a mechanism for mixing vendor-specific requests with
the previously described standard device requests. Bits 6:5 of the bmRequest field are set to 00
for a standard device request, and to 10 for a vendor request.
Table 7-21. Firmware Download
Byte
Field
Value
Meaning
8051 Response
0
bmRequestType
0x40
Vendor Request, OUT
1
bRequest
0xA0
“Firmware Load”
2
wValueL
AddrL
Starting address
3
wValueH
AddrH
4
wIndexL
0x00
5
wIndexH
0x00
6
wLengthL
LenL
7
wLengthH
LenH
None required
Number of bytes
Table 7-22. Firmware Upload
Byte
Field
Value
Meaning
0
bmRequestType
0xC0
Vendor Request, IN
1
bRequest
0xA0
“Firmware Load”
2
wValueL
AddrL
Starting address
3
wValueH
AddrH
4
wIndexL
0x00
5
wIndexH
0x00
6
wLengthL
LenL
7
wLengthH
LenH
8051 Response
None Required
Number of Bytes
The EZ-USB core responds to two endpoint zero vendor requests, RAM Download and RAM
Upload. These requests are active in all modes (ReNum=0 or 1).
Because bit 7 of the first byte of the SETUP packet specifies direction, only one bRequest value
(0xA0) is required for the upload and download requests. These RAM load commands are available to any USB device that uses the EZ-USB chip.
A host loader program typically writes 0x01 to the CPUCS register to put the 8051 into RESET,
loads all or part of the EZ-USB internal RAM with 8051 code, and finally reloads the CPUCS register with 0 to take the 8051 out of RESET. The CPUCS register is the only USB register that can be
written using the Firmware Download command.
Page 7-22
EZ-USB Technical Reference Manual v1.10
Chapter 8
8.1
EZ-USB Isochronous Transfers
Introduction
Isochronous endpoints typically handle time-critical, streamed data that is delivered or consumed
in byte-sequential order. Examples might be audio data sent to a DAC over USB, or teleconferencing video data sent from a camera to the host. Due to the byte-sequential nature of this data, the
EZ-USB chip makes isochronous data available as a single byte that represents the head or tail of
an endpoint FIFO.
The EZ-USB chips that support isochronous transfers implement sixteen isochronous endpoints,
IN8-IN15 and OUT8-OUT15. 1,024 bytes of FIFO memory may be distributed over the 16 endpoint
addresses. FIFO sizes for the isochronous endpoints are programmable.
OUTnDATA Register
(n=8-15)
8051 FIFO
SOF
USB FIFO
INnDATA Register
(n=8-15)
USB
OUT
Data
8051 FIFO
SOF
USB FIFO
USB
IN
Data
Figure 8-1. EZ-USB Isochronous Endpoints 8-15
The 8051 reads or writes isochronous data using sixteen FIFO data registers, one per endpoint.
These FIFO registers are shown in Figure 8-1 as INnDATA (Endpoint n IN Data) and OUTnDATA
(Endpoint n OUT Data).
Chapter 8. EZ-USB Isochronous Transfers
Page 8-1
EZ-USB Technical Reference Manual
The EZ-USB core provides a total of 2,048 bytes of FIFO memory (1,024 bytes, double-buffered)
for ISO endpoints. This memory is in addition to the 8051 program/data memory, and normally
exists outside of the 8051 memory space. The 1,024 FIFO bytes may be divided among the sixteen isochronous endpoints. The 8051 writes sixteen EZ-USB registers to allocate the FIFO
buffer space to the isochronous endpoints. The 8051 also sets endpoint valid bits to enable isochronous endpoints.
8.2
Isochronous IN Transfers
IN transfers travel from device to host. Figure 8-2 shows the EZ-USB registers and bits associated with isochronous IN transfers.
Registers Associated with an ISO IN endpoint
(EP8IN shown as example)
Initialization
INISOVAL
15
14
13
12
Data transfer
11
10
9
8
IN8DATA
7
6
Endpoint Valid (1=valid)
IN8ADDR
A9
A8
A7
A6
A5
A4
0
7
6
5
4
3
2
1
4
3
2
1
0
1
0
Data to USB
0
FIFO Start Address (see text)
USBPAIR
5
USBIRQ
7
6
5
4
3
2
SOFIR (1=clear request)
0
ISOSEND0 (see text)
USBIEN
7
6
5
4
3
2
1
0
SOFIE (1=enabled)
Figure 8-2. Isochronous IN Endpoint Registers
8.2.1 Initialization
To initialize an isochronous IN endpoint, the 8051 performs the following:
•
Sets the endpoint valid bit for the endpoint.
•
Sets the endpoint’s FIFO size by loading a starting address (Section 8.4, "Setting Isochronous FIFO Sizes").
•
Sets the ISOSEND0 bit in the USBPAIR register for the desired response.
Page 8-2
EZ-USB Technical Reference Manual v1.10
•
Enables the SOF interrupt. All isochronous endpoints are serviced in response to the SOF
interrupt.
The EZ-USB core uses the ISOSEND0 bit to determine what to do if:
•
The 8051 does not load any bytes to an INnDATA register during the previous frame, and
•
An IN token for that endpoint arrives from the host.
If ISOSEND0=0 (the default value), the EZ-USB core does not respond to the IN token. If
ISOSEND0=1, the EZ-USB core sends a zero-length data packet in response to the IN token.
Which action to take depends on the overall system design. The ISOSEND0 bit applies to all of
the isochronous IN endpoints, EP8IN through EP15IN.
8.2.2 IN Data Transfers
When an SOF interrupt occurs, the 8051 is presented with empty IN FIFOs that it fills with data to
be transferred to the host during the next frame. The 8051 has 1 ms to transfer data into these
FIFOs before the next SOF interrupt arrives.
To respond to the SOF interrupt, the 8051 clears the USB interrupt (8051 INT2), and clears the
SOFIR (Start Of Frame Interrupt Request) bit writing a “1” to it. Then, the 8051 loads data into the
appropriate isochronous endpoint. The EZ-USB core keeps track of the number of bytes the 8051
loads to each INnDATA register, and subsequently transfers the correct number of bytes in
response to the USB IN token during the next frame.
The EZ-USB FIFO swap occurs every SOF, even if during the previous frame the host did not
issue an IN token to read the isochronous FIFO data, or if the host encountered an error in the
data. USB isochronous data has no re-try mechanism like bulk data.
8.3
Isochronous OUT Transfers
OUT transfers travel from host to device. Figure 8-3 shows the EZ-USB registers and bits associated with isochronous OUT transfers.
Chapter 8. EZ-USB Isochronous Transfers
Page 8-3
EZ-USB Technical Reference Manual
Registers Associated with an ISO OUT endpoint
(EP15OUT shown as example)
Data transfer
Initialization
OUTISOVAL
14
15
13
12
11
10
9
8
OUT15DATA
7
6
A9
A8
A7
A6
A5
A4
0
0
FIFO Start Address (see text)
USBIEN
7
6
5
4
3
2
1
4
3
2
1
0
1
0
Data from USB
Endpoint Valid (1=valid)
OUT15ADDR
5
USBIRQ
7
6
5
4
3
2
SOFIR (1=clear request)
0
SOFIE (1=enabled)
OUT15BCH
7
6
5
4
3
2
9
8
Received Byte Count (H)
OUT15BCL
7
6
5
4
3
2
1
0
Received Byte Count (L)
ISOERR
15
14
13
12
11
10
9
8
OUT15 CRC Error (1=error)
Figure 8-3. Isochronous OUT Registers
8.3.1 Initialization
To initialize an isochronous OUT endpoint, the 8051:
•
Sets the endpoint valid bit for the endpoint.
•
Sets the endpoint’s FIFO size by loading a starting address (Section 8.4, "Setting Isochronous FIFO Sizes").
•
Enables the SOF interrupt. All isochronous endpoints are serviced in response to the
SOF interrupt.
Page 8-4
EZ-USB Technical Reference Manual v1.10
8.3.2 OUT Data Transfer
When an SOF interrupt occurs, the 8051 is presented with FIFOs containing OUT data sent from
the host in the previous frame, along with 10-bit byte counts, indicating how many bytes are in the
FIFOs. The 8051 has 1 ms to transfer data out of these FIFOs before the next SOF interrupt
arrives.
To respond to the SOF interrupt, the 8051 clears the USB interrupt (8051 INT2), and clears the
SOFIR bit by writing one to it. Then, the 8051 reads data from the appropriate OUTnDATA FIFO
register(s). The 8051 can check an error bit in the ISOERR register to determine if a CRC error
occurred for the endpoint data. Isochronous data is never present, so the firmware must decide
what to do with bad-CRC data.
8.4
Setting Isochronous FIFO Sizes
Up to sixteen EZ-USB isochronous endpoints share an EZ-USB 1,024-byte RAM which can be
configured as one to sixteen FIFOs. The 8051 initializes the endpoint FIFO sizes by specifying the
starting address for each FIFO within the 1,024 bytes, starting at address zero. The isochronous
FIFOs can exist anywhere in the 1,024 bytes, but the user must take care to ensure that there is
sufficient space between start addresses to accommodate the endpoint FIFO size.
Sixteen start address registers set the isochronous FIFO sizes (Table 8-1). The EZ-USB core constructs the address writing the 1,024 byte range from the register value as shown in Figure 8-4.
Address
A9
A8
A7
A6
A5
A4
0
0
0
0
Register
Figure 8-4. FIFO Start Address Format
Chapter 8. EZ-USB Isochronous Transfers
Page 8-5
EZ-USB Technical Reference Manual
Table 8-1. Isochronous Endpoint FIFO Starting Address Registers
b7
b6
b5
b4
b3
b2
b1
b0
OUT8ADDR
Register
Endpoint 8 OUT Start Address
Function
A9
A8
A7
A6
A5
A4
0
0
OUT9ADDR
Endpoint 9 OUT Start Address
A9
A8
A7
A6
A5
A4
0
0
OUT10ADDR
Endpoint 10 OUT Start Address
A9
A8
A7
A6
A5
A4
0
0
OUT11ADDR
Endpoint 11 OUT Start Address
A9
A8
A7
A6
A5
A4
0
0
OUT12ADDR
Endpoint 12 OUT Start Address
A9
A8
A7
A6
A5
A4
0
0
OUT13ADDR
Endpoint 13 OUT Start Address
A9
A8
A7
A6
A5
A4
0
0
OUT14ADDR
Endpoint 14 OUT Start Address
A9
A8
A7
A6
A5
A4
0
0
OUT15ADDR
Endpoint 15 OUT Start Address
A9
A8
A7
A6
A5
A4
0
0
IN8ADDR
Endpoint 8 IN Start Address
A9
A8
A7
A6
A5
A4
0
0
IN9ADDR
Endpoint 9 IN Start Address
A9
A8
A7
A6
A5
A4
0
0
IN10ADDR
Endpoint 10 IN Start Address
A9
A8
A7
A6
A5
A4
0
0
IN11ADDR
Endpoint 11 IN Start Address
A9
A8
A7
A6
A5
A4
0
0
IN12ADDR
Endpoint 12 IN Start Address
A9
A8
A7
A6
A5
A4
0
0
IN13ADDR
Endpoint 13 IN Start Address
A9
A8
A7
A6
A5
A4
0
0
IN14ADDR
Endpoint 14 IN Start Address
A9
A8
A7
A6
A5
A4
0
0
IN15ADDR
Endpoint 15 IN Start Address
A9
A8
A7
A6
A5
A4
0
0
The size of an isochronous endpoint FIFO is determined by subtracting consecutive addresses in
Table 8-1, and multiplying by four. Values written to these registers should have the two LSBs set
to zero. The last endpoint, EP15IN, has a size of 1,024 minus IN15ADDR times four. Because
the 10-bit effective address has the four LSBs set to zero (Figure 8-4), the FIFO sizes are allocated in increments of 16 bytes. For example, if OUT8ADDR=0x00 and OUT9ADDR=0x04,
EP8OUT has a FIFO size of the difference multiplied by four or 16 bytes.
An 8051 assembler or C compiler may be used to translate FIFO sizes into starting addresses.
The assembler example in Figure 8-5 shows a block of equates for the 16 isochronous FIFO
sizes, followed by assembler equations to compute the corresponding FIFO relative address values. To initialize all sixteen FIFO sizes, the 8051 merely copies the table starting at 8OUTAD to
the sixteen EZ-USB registers starting at OUT8ADDR.
Page 8-6
EZ-USB Technical Reference Manual v1.10
0100
EP8INSZ
equ
256
0100
EP8OUTSZ
equ
256
; Iso FIFO sizes in bytes
0010
EP9INSZ
equ
16
0010
EP9OUTSZ
equ
16
0010
EP10INSZ
equ
16
0010
EP10OUTSZ
equ
16
0000
EP11INSZ
equ
0
0000
EP11OUTSZ
equ
0
0000
EP12INSZ
equ
0
0000
EP12OUTSZ
equ
0
0000
EP13INSZ
equ
0
0000
EP13OUTSZ
equ
0
0000
EP14INSZ
equ
0
0000
EP14OUTSZ
equ
0
0000
EP15INSZ
equ
0
0000
EP15OUTSZ
equ
0
0000
8OUTAD
equ
0
; Load these 16 bytes into ADDR regs starting OUT8ADDR
0040
9OUTAD
equ
8OUTAD
+ Low(EP8OUTSZ/4)
0044
10OUTAD
equ
9OUTAD
+ Low(EP9OUTSZ/4)
0048
11OUTAD
equ
10OUTAD + Low(EP10OUTSZ/4)
0048
12OUTAD
equ
11OUTAD + Low(EP11OUTSZ/4)
0048
13OUTAD
equ
12OUTAD + Low(EP12OUTSZ/4)
0048
14OUTAD
equ
13OUTAD + Low(EP13OUTSZ/4)
0048
15OUTAD
equ
14OUTAD + Low(EP14OUTSZ/4)
0048
8INAD
equ
15OUTAD + Low(EP15OUTSZ/4)
0088
9INAD
equ
8INAD
+ Low(EP8INSZ/4)
008C
10INAD
equ
9INAD
+ Low(EP9INSZ/4)
0090
11INAD
equ
10INAD
+ Low(EP10INSZ/4)
0090
12INAD
equ
11INAD
+ Low(EP11INSZ/4)
0090
13INAD
equ
12INAD
+ Low(EP12INSZ/4)
0090
14INAD
equ
13INAD
+ Low(EP13INSZ/4)
0090
15INAD
equ
14INAD
+ Low(EP14INSZ/4)
;
Figure 8-5. Assembler Translates FIFO Sizes to Addresses
The assembler computes starting addresses in Figure 8-5 by adding the previous endpoint’s
address to the desired size shifted right twice. This aligns A9 with bit 7 as shown in Table 8-1. The
LOW operator takes the low byte of the resulting 16 bit expression
The user of this code must ensure that the sizes given in the first equate block are all multiples of
16. This is easy to tell by inspection—the least significant digit of the hex values in the first column
should be zero.
Chapter 8. EZ-USB Isochronous Transfers
Page 8-7
EZ-USB Technical Reference Manual
8.5
Isochronous Transfer Speed
The amount of data USB can transfer during a 1-ms frame is slightly more than 1,000 bytes per
frame (1,500 bytes theoretical, without accounting for USB overhead and bus utilization). A
device’s actual isochronous transfer bandwidth is usually determined by how fast the CPU can
move data in and out of its isochronous endpoint FIFOs.
The 8051 code example in Figure 8-6 shows a typical transfer loop for moving external FIFO data
into an IN endpoint FIFO. This code assumes that the 8051 is moving data from an external FIFO
attached to the EZ-USB data bus and strobed by the RD signal, into an internal isochronous IN
FIFO.
mov
dptr,#8000H
; pointer to any outside address
inc
dps
; switch to second data pointer
mov
dptr,#IN8DATA
; pointer to an IN endpoint FIFO (IN8 as example)
inc
dps
; back to first data pointer
mov
r7,#nBytes
; r7 is loop counter—transfer this many bytes
;
loop:
movx
a,@dptr
; (2) read byte from external bus to acc
inc
dps
; (2) switch to second data pointer
movx
@dptr,a
; (2) write to ISO FIFO
inc
dps
; (2) switch back to first data pointer
djnz
r7,loop
; (3) loop ‘nBytes’ times
Figure 8-6. 8051 Code to Transfer Data to an Isochronous FIFO (IN8DATA)
The numbers in parentheses indicate 8051 cycles. One cycle is four clocks, and the EZ-USB
8051 is clocked at 24 MHz (42 ns). Thus, an 8051 cycle takes 4*42=168 ns, and the loop takes 9
cycles or 1.5 µs. This loop can transfer about 660 bytes into an IN FIFO every millisecond (1 ms/
1.5 µs).
If more speed is required, the loop can be unrolled by in-line coding the first four instructions in the
loop. Then, a byte is transferred in 6 cycles (24 clocks) which equates to 1 µs per byte. Using this
method, the 8051 could transfer 1,000 bytes into an IN FIFO every millisecond. In practice, a better solution is to in-line code only a portion of the loop code, which decreases full in-line performance only slightly and uses far fewer bytes of program code.
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EZ-USB Technical Reference Manual v1.10
8.6
Fast Transfers
EZ-USB has a special fast transfer mode for applications that use external FIFOs connected to the
EZ-USB data bus. These applications typically require very high transfer speeds in and out of EZUSB endpoint buffers.
DPTR
EZ-USB
Registers
(Addressed
as external
RAM)
movx a,@dptr
movx @dptr,a
Accumulator
Figure 8-7. 8051 MOVX Instructions
The 8051 transfers data to and from EZ-USB registers and RAM using the MOVX (move external)
instruction (Figure 8-7). The 8051 loads one of its two 16-bit data pointers (DPTR) with an address
in RAM, and then executes a MOVX instruction to transfer data between the accumulator and the
byte addressed by DPTR. The “@” symbol indicates that the address is supplied indirectly, by the
DPTR.
The EZ-USB core monitors MOVX transfers between the accumulator and any of the sixteen isochronous FIFO registers. If an enable bit is set (FISO=1 in the FASTXFR register), any read or
write to an isochronous FIFO register causes the EZ-USB core to connect the data to the EZ-USB
data bus D[7..0], and generate external read/write strobes. One MOVX instruction thus transfers a
byte of data in or out of an endpoint FIFO and generates timing strobes for an outside FIFO or
memory. The 2-cycle MOVX instruction takes 2 cycles or 333 ns. Figures 8-8 and 8-9 show the
data flow for fast writes and reads over the EZ-USB data bus.
Fast Bulk Transfers
The EZ-USB core provides a special auto-incrementing data pointer that makes the fast transfer
mechanism available for bulk transfers. The 8051 loads a 16-bit RAM address into the AUTOPTRH/L registers, and then accesses RAM data as a FIFO using the AUTODATA register. Section
6.16, "The Autopointer" describes this special pointer and register.
Chapter 8. EZ-USB Isochronous Transfers
Page 8-9
EZ-USB Technical Reference Manual
8.6.1 Fast Writes
ISO OUT FIFO
movx a,@dptr
DPTR
FWR#
D[7..0]
External FIFO
or ASIC
Accumulator
Figure 8-8. Fast Transfer, EZ-USB to Outside Memory
Fast writes are illustrated in Figure 8-8. When the fast mode is enabled, the DPTR points to an
isochronous OUT FIFO register, and the 8051 executes the “movx a,@dptr” instruction, the EZUSB core broadcasts the data from the isochronous FIFO to the outside world via the data bus
D[7..0], and generates a Write Strobe FWR# (Fast Write). A choice of eight waveforms is available for the write strobe, as shown in the next section.
8.6.2 Fast Reads
ISO IN FIFO
movx @dptr,a
DPTR
FRD#
D[7..0]
External FIFO
or ASIC
Accumulator
Figure 8-9. Fast Transfer, Outside Memory to EZ-USB
Fast reads are illustrated in Figure 8-9. When the fast mode is enabled, the DPTR points to an
isochronous OUT FIFO register, and the 8051 executes the “movx @dptr,a” instruction, the EZ-
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EZ-USB Technical Reference Manual v1.10
USB core breaks the data path from the accumulator to the IN FIFO register, and instead writes
the IN FIFO using outside data from D[7..0]. The EZ-USB core synchronizes this transfer by generating a FIFO Read Strobe FRD# (Fast Read). A choice of eight waveform is available for the
read strobe, as shown in the next section.
8.7
Fast Transfer Timing
The 8051 sets bits in the FASTXFR register to select the fast ISO and/or fast BULK mode and to
adjust the timing and polarity of the read and write strobes FRD# and FWR#.
FASTXFR
Fast Transfer Control
7FE2
b7
b6
b5
b4
b3
b2
b1
b0
FISO
FBLK
RPOL
RMOD1
RMOD0
WPOL
WMOD1
WMOD0
Figure 8-10. The FASTXFR Register Controls FRD# and FWR# Strobes
The 8051 sets FISO=1 to select the fast ISO mode and FBLK=1 to select the fast Bulk mode. The
8051 selects read and write strobe pulse polarities with the RPOL and WPOL bits, where 0=active
low, and 1=active high. Read and write strobe timings are set by RMOD1-RMOD0 for read strobes
and WMOD1-WMOD0 for write strobes, as shown in Figure 8-11 (write) and Figure 8-12 (read).
Note
When using the fast transfer feature, be sure to enable the FRD# and FWR# strobe signals in the
PORTACFG register.
Chapter 8. EZ-USB Isochronous Transfers
Page 8-11
EZ-USB Technical Reference Manual
8.7.1 Fast Write Waveforms
tCL
41.66 ns
CLK24
D[7..0]
stretch=000
Output
stretch=000
FWR#[00]
stretch=000
FWR#[01]
stretch=000
FWR#[10]
stretch=000
FWR#[11]
D[7..0]
Output
stretch=001
FWR#[00]
stretch=001
FWR#[01]
stretch=001
FWR#[10]
stretch=001
FWR#[11]
stretch=001
[nn] = WM1:WM0, WPOL=0
Note: If WPOL=1 the waveforms are inverted
Figure 8-11. Fast Write Timing
The timing choices for fast write pulses (FWR#) are shown in Figure 8-11. The 8051 can extend
the output data and widths of these pulses by setting cycle stretch values greater than zero in the
8051 Clock Control Register CKCON (at SFR location 0x8E). The top five waveforms show the
fastest write timings, with a stretch value of 000, which performs the write in eight 8051 clocks.
The bottom five waveforms show the same waveforms with a stretch value of 001.
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8.7.2 Fast Read Waveforms
tCL
41.66 ns
OSC24
In
D[7..0]
stretch=000, 001
FRD#[00]
In
D[7..0]
stretch=000, 001
FRD#[01]
In
D[7..0]
FRD#[10]
stretch=000
FRD#[10]
stretch=001
In
D[7..0]
FRD#[11]
stretch=000
FRD#[11]
stretch=001
[nn] = RMOD1:RMOD0, RPOL=0
Note: If WPOL=1 the waveforms are inverted
Figure 8-12. Fast Read Timing
The timing choices for fast read pulses (FRD#) are shown in Figure 8-12. Read Strobe waveforms
for stretch values of 000 and 001 are indicated. Although two of the read strobe widths can be
extended using stretch values greater than 000, the times that the input data is sampled by the EZUSB core remains the same as shown.
FRD# strobes[00] and [01], along with the OSC24 clock signal are typically used to connect to an
external synchronous FIFO. The on-clock-wide read strobe ensures that the FIFO address
advances only once per clock. The second strobe [01] is for FIFOs that put data on the bus one
clock after the read strobe. Stretch values above 000 serve only to extend the 8051 cycle times,
without affecting the width of the FRD# strobe.
FRD# strobes [10] and [11] are typically connected to an external asynchronous FIFO, where no
clock is required. Strobe [10] samples the data at the same time as strobe [11], but provides a
Chapter 8. EZ-USB Isochronous Transfers
Page 8-13
EZ-USB Technical Reference Manual
wider pulse width (for stretch=000), which is required by some audio CODECS. Timing values for
these strobe signals are given in Chapter 13, “EZ-USB AC/DC Parameters.”
8.8
Fast Transfer Speed
The 8051 code example in Figure 8-13 shows a transfer loop for moving external FIFO data into
the endpoint 8-IN FIFO. This code moves data from an external FIFO attached to the EZ-USB
data bus and strobed by the FRD# signal, into the FIFO register IN8DATA
(init)
mov
dptr,#FASTXFR
; set up the fast ISO transfer mode
mov
a,#10000000b
; FISO=1, RPOL=0, RM1-0 = 00
movx
@dptr,a
; load the FASTXFR register
mov
dptr,#IN8DATA
; pointer to IN endpoint FIFO
mov
r7,#80
; r7 is loop counter, 8 bytes per loop
;
loop:
movx
@dptr,a
; (2) write IN FIFO using byte from external bus
movx
@dptr,a
; (2) again
movx
@dptr,a
; (2) again
movx
@dptr,a
; (2) again
movx
@dptr,a
; (2) again
movx
@dptr,a
; (2) again
movx
@dptr,a
; (2) again
movx
@dptr,a
; (2) again
djnz
r7,loop
; (3) do eight more, ‘r7’ times
Figure 8-13. 8051 Code to Transfer 640 Bytes of External Data to an Isochronous IN FIFO
This routine uses a combination of in-line and looped code to transfer 640 bytes into the EP8IN
FIFO from an external FIFO. The loop transfers eight bytes in 19 cycles, and it takes 80 times
through the loop to transfer 640 bytes. Therefore, the total transfer time is 80 times 19 cycles, or
1,520 cycles. The 640 byte transfer thus takes 1,520*166 ns or 252 µs, or approximately onefourth of the 1-ms USB frame time.
Using this routine, the time to completely fill one isochronous FIFO with 1,024 bytes (assuming all
1,024 isochronous FIFO bytes are assigned to one endpoint) would be 128 times 19 cycles, or
2,432 cycles. The 1,024 byte transfer would take 403 µs, less than half of the 1-ms USB frame
time.
If still faster time is required, the routine can be modified to put more of the MOVX instructions inline. For example, with 16 in-line MOVX instructions, the transfer time for 1,024 bytes would be 35
cycles times 64 loops or 2,240 cycles, or 371 µs, an 8% speed improvement over the eight instruction loop.
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EZ-USB Technical Reference Manual v1.10
8.9
Other Isochronous Registers
Two additional registers, ISOCTL and ZBCOUT, provide additional isochronous endpoint features.
8.9.1 Disable ISO
ISOCTL
Isochronous Control
7FA1
b7
b6
b5
b4
b3
b2
b1
b0
-
-
-
-
PPSTAT
MBZ
MBZ
ISODISAB
Figure 8-14. ISOCTL Register
Bit zero of the ISOCTL register is called ISODISAB. When the 8051 sets ISODISAB=1, all sixteen
of EZ-USB endpoints are disabled. If ISODISAB=1, EP8IN=EP15IN and EP8OUT-EP15OUT
should not be used. ISODISAB is cleared at power-on.
When ISODISAB=1, the 2,048 bytes of RAM normally used for isochronous buffers is available to
the 8051 as XDATA RAM (not program memory), from 0x2000 to 0x27FF in internal memory.
When ISODISAB=1, the behavior of the RD# and WR# strobe signals changes to reflect the additional 2 KB of memory inside the EZ-USB chip. This is shown in Table 8-2.
Table 8-2. Addresses for RD# and WR# vs. ISODISAB bit
ISODISAB
RD#, WR#
0
(default)
2000-7B40,
8000-FFFF
1
2800-7B40,
8000-FFFF
ISOCTL register bits shown as MBZ (must be zero) must be written with zeros. The PPSTAT bit
toggles every SOF, and may be written with any value (no effect). Therefore, to disable the isochronous endpoints, the 8051 should write the value 0x01 to the ISOCTL register.
Caution!
If you use this option, be absolutely certain that the host never sends isochronous data to your
device. Isochronous data directed to a disabled isochronous endpoint system will cause unpredictable operation.
Chapter 8. EZ-USB Isochronous Transfers
Page 8-15
EZ-USB Technical Reference Manual
Note
The Autopointer is not usable from 0x2000-0x27FF (the reclaimed ISO buffer RAM) when ISODISAB=1.
8.9.2 Zero Byte Count Bits
When the SOF interrupt is asserted, the 8051 normally checks the isochronous OUT endpoint
FIFOs for data. Before reading the byte count registers and unloading an isochronous FIFO, the
firmware may wish to check for a zero byte count. In this case, the 8051 can check bits in the
ZBCOUT register. Any endpoint bit set to “1” indicates that no OUT bytes were received for that
endpoint during the previous frame. Figure 8-15 shows this register.
ZBCOUT
Zero Byte Count Bits
7FA2
b7
b6
b5
b4
b3
b2
b1
b0
EP15
EP14
EP13
EP12
EP11
EP10
EP9
EP8
Figure 8-15. ZBCOUT Register
The EZ-USB core updates these bits every SOF.
8.10
ISO IN Response with No Data
The ISOSEND0 bit (bit 7 in the USBPAIR register) is used when the EZ-USB chip receives an isochronous IN token while the IN FIFO is empty. If ISOSEND0=0 (the default value) the EZ-USB
core does not respond to the IN token. If ISOSEND0=1, the EZ-USB core sends a zero-length
data packet in response to the IN token. Which action to take depends on the overall system
design. The ISOSEND0 bit applies to all of the isochronous IN endpoints, IN-8 through IN-15.
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EZ-USB Technical Reference Manual v1.10
8.11
Using the Isochronous FIFOs
There is a window of time before and after each SOF (Start of Frame) when accessing the Isochronous FIFOs will cause data corruption or loss of data.
This is because each isochronous endpoint is actually a pair of FIFOs, and the FIFOs are swapped
at SOF time. The swap occurs about 10 µs before the SOF interrupt signals the 8051 code.
(Between SOFs, one FIFO of the pair is accessible to the 8051, while the other FIFO of the pair
transfers data to or from the USB.)
Workaround#1: If you can pre-assemble the data into a buffer, blast the data (in a tight loop) into
the new FIFO just after the SOF interrupt, typically inside the SOF ISR (Interrupt Service Routine).
Workaround#2: If you can’t pre-assemble the data into a buffer, prevent access during SOFs by
setting a time (in the SOF ISR) to time out and halt access just before the next SOF. Set the timer
for about 950 µs (ms minus 50 µs).
Be careful of interrupt latency delaying the timeout ISR. That is, the timeout ISR may be prevented
from halting access by getting preempted by a higher priority interrupt(s), made worse by the necessary practice of disabling interrupts to manage shared resources, resources that are shared
between the ISRs and background process.
To prevent drift of the timer relative to SOFs, restart the timer after each SOF (typically in the SOF
ISR).
Chapter 8. EZ-USB Isochronous Transfers
Page 8-17
EZ-USB Technical Reference Manual
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EZ-USB Technical Reference Manual v1.10
Chapter 9
9.1
EZ-USB Interrupts
Introduction
The EZ-USB enhanced 8051 responds to the interrupts shown in Table 9-1. Interrupt sources that
are not present in the standard 8051 are shown as checked in the “New” column. The three interrupts used by the EZ-USB core are shown in bold type.
Table 9-1. EZ-USB Interrupts
New
P
8051 Interrupt (IRQ name)
Source
Vector (hex)
Natural Priority
IE0
INT0# Pin
03
1
TF0
Timer 0 Overflow
0B
2
IE1
INT1# Pin
13
3
TF1
Timer 1 Overflow
1B
4
RI_0 & TI_0
UART0 Rx & Tx
23
5
TF2
Timer 2 Overflow
2B
6
P
Resume (PFI)
WAKEUP# Pin or USB Core
33
0
P
RI_1 & TI_1
UART1 Rx & Tx
3B
7
P
USB (INT2)
USB Core
43
8
P
I C (INT3)
USB Core
4B
9
P
IE4
IN4 Pin
53
10
P
IE5
INT5# Pin
5B
11
P
IE6
INT6 Pin
63
12
2
The Natural Priority column in Table 9-1 shows the 8051 interrupt priorities. As explained in
Appendix C, the 8051 can assign each interrupt to a high or low priority group. The 8051 resolves
priorities within the groups using the natural priorities.
Chapter 9. EZ-USB Interrupts
Page 9-1
EZ-USB Technical Reference Manual
9.2
USB Core Interrupts
The EZ-USB core provides three interrupt request types, which are described in the following sections:
Wakeup - After the EZ-USB chip detects USB suspend and the 8051 has entered its idle
state, the EZ-USB core responds to an external signal on its WAKEUP# pin or
resumption of USB bus activity by re-starting the EZ-USB oscillator and resuming
8051 operation.
USB Signaling - These include 16 bulk endpoint interrupts, three interrupts not specific to
a particular endpoint (SOF), Suspend, USB Reset), and two interrupts for CONTROL transfers (SUTOK, SUDAV). These interrupts share the USB interrupt
(INT2).
I2C Transfers - (INT3).
9.3
Wakeup Interrupt
Chapter 10, "EZ-USB Resets" describes suspend-resume signaling in detail, along with a code
example that uses the Wakeup interrupt.
Briefly, the USB host puts a device into SUSPEND by stopping bus activity to the device. When
the EZ-USB core detects 3 ms of no bus activity, it activates the USB suspend interrupt request. If
enabled, the 8051 takes the suspend interrupt, does power management housekeeping (shutting
down power to external logic), and finishes by setting SFR bit PCON.0. This signals the EZ-USB
core to enter a very low power mode by turning off the 12-MHz oscillator.
When the 8051 sets PCON.0, it enters an idle state. 8051 execution is resumed by activation of
any enabled interrupt. The EZ-USB chip uses a dedicated interrupt for USB Resume. When
external logic pulls WAKEUP# low (for example, when a keyboard key is pressed or a modem
receives a ring signal) or USB bus activity resumes, the EZ-USB core re-starts the 12-MHz oscillator, allowing the 8051 to recognize the interrupt and continue executing instructions.
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EZ-USB Technical Reference Manual v1.10
EICON.5
Resume signal
from EZ-USB core
S
R
8051
"RESUME"
Interrupt
EICON.4(rd)
EICON.4(0)
Figure 9-1. EZ-USB Wakeup Interrupt
Figure 9-1 shows the 8051 SFR bits associated with the RESUME interrupt. The EZ-USB core
asserts the resume signal when the EZ-USB core senses a USB Global Resume, or when the EZUSB WAKEUP# pin is pulled low. The 8051 enables the RESUME interrupt by setting EICON.5.
tb
EICON.5
; enable Resume interrupt
The 8051 reads the RESUME interrupt request bit in EICON.4, and clears the interrupt request by
writing a zero to EICON.4.
Resume_isr:
clr
EICON.4
; clear the 8051 W/U
; interrupt request
reti
9.4
USB Signaling Interrupts
Figure 9-2 shows the 21 USB requests that share the 8051 USB (INT2) interrupt. The bottom IRQ,
EP7-OUT, is expanded in the diagram to show the logic associated with each USB interrupt
request.
Chapter 9. EZ-USB Interrupts
Page 9-3
EZ-USB Technical Reference Manual
EZ-USB
00
SUDAV
01
SOF
02
SUTOK
03
SUSP
04
URES
05
IBN Int
06
EP0-IN
07
EP0-OUT
08
EP1-IN
09
EP1-OUT
0A
EP2-IN
0B
EP2-OUT
0C
EP3-IN
0D
EP3-OUT
0E
EP4-IN
0F
EP4-OUT
10
EP5-IN
11
EP5-OUT
12
EP6-IN
13
EP6-OUT
14
EP7-IN
8051
EIE.0
8051 "USB"
Interrupt
S
R
EXIF.4(rd)
EXIF.4(0)
OUT07IEN.7
15
EP7-OUT
S
IN07IRQ.7(1)
R
IN07IRQ.7 (rd)
Interrupt Request Latch
IVEC
0
IV4
IV3
IV2
IV1
IV0
0
0
Figure 9-2. USB Interrupts
Referring to the logic inside the dotted lines, each USB interrupt source has an interrupt request
latch. The EZ-USB core sets an IRQ bit, and the 8051 clears an IRQ bit by writing a “1” to it. The
output of each latch is ANDed with an IEN (Interrupt Enable) bit and then ORed with all the other
USB interrupt request sources.
The EZ-USB core prioritizes the USB interrupts, and constructs an Autovector, which appears in
the IVEC register. The interrupt vector values IV[4..0] are shown to the left of the interrupt sources
(shaded boxes). 00 is the highest priority, 15 is the lowest. If two USB interrupts occur simultaneously, the prioritization affects which one is first indicated in the AVEC register. If the 8051 has
enabled Autovectoring, the IVEC byte replaces byte 0x45 in 8051 program memory. This causes
Page 9-4
EZ-USB Technical Reference Manual v1.10
the USB interrupt automatically to vector to different addresses for each USB interrupt source.
This mechanism is explained in detail in Section 9.10, "USB Autovectors."
Due to the OR gate in Figure 9-2, any of the USB interrupt sources sets the 8051 USB interrupt
request latch, whose state appears as an interrupt request in the 8051 SFR bit EXIF.4. The 8051
enables the USB interrupt by setting SFR bit EIE.0. To clear the USB interrupt request the 8051
writes a zero to the EXIF.4 bit. Note that this is the opposite of clearing any of the individual USB
interrupt sources, which the 8051 does by writing a “1” to the IRQ bit.
When a USB resource requires service (for example, a SOF token arrives or an OUT token arrives
on a BULK endpoint), two things happen. First, the corresponding Interrupt Request Latch is set.
Second, a pulse is generated, ORed with the other USB interrupt logic, and routed to the 8051
INT2 input. The pulse is required because INT2 is edge triggered.
When the 8051 finishes servicing a USB interrupt, it clears the particular IRQ bit by writing a “1” to
it. If any other USB interrupts are pending, the act of clearing the IRQ causes the EZ-USB core
logic to generate another pulse for the highest-priority pending interrupt. If more that one is pending, they are serviced in the priority order shown in Figure 9-2, starting with SUDAV (priority 00) as
the highest priority, and ending with EP7-OUT (priority 15) as the lowest.
Important
It is important in any USB Interrupt Service Routine (ISR) to clear the 8051 INT2 interrupt before
clearing the particular USB interrupt request latch. This is because as soon as the USB interrupt
is cleared, any pending USB interrupt will pulse the 8051 INT2 input, and if the INT2 interrupt
request latch has not been previously cleared the pending interrupt will be lost.
Figure 9-3 illustrates a typical USB ISR for endpoint 2-IN.
Chapter 9. EZ-USB Interrupts
Page 9-5
EZ-USB Technical Reference Manual
USB_ISR:
push
push
push
push
push
push
dps
dpl
dph
dpl1
dph1
acc
mov
clr
mov
a,EXIF
acc.4
EXIF,a
; FIRST clear the USB (INT2) interrupt request
mov
mov
movx
dptr,#IN07IRQ
a,#00000100b
@dptr,a
; now clear the USB interrupt request
; use IN2 as example
;
; Note:
EXIF reg is not 8051 bit-addressable
;
;
; (perform interrupt routine stuff)
;
pop
acc
pop
dph1
pop
dpl1
pop
dph
pop
dpl
pop
dps
;
reti
Figure 9-3. The Order of Clearing Interrupt Requests is Important
Page 9-6
EZ-USB Technical Reference Manual v1.10
IN07IRQ
Endpoints 0-7 IN Interrupt Requests
7FA9
b7
b6
b5
b4
b3
b2
b1
b0
IN7IR
IN6IR
IN5IR
IN4IR
IN3IR
IN2IR
IN1IR
IN0IR
OUT07IRQ
Endpoints 0-7 OUT Interrupt Requests
7FAA
b7
b6
b5
b4
b3
b2
b1
b0
OUT7IR
OUT6IR
OUT5IR
OUT4IR
OUT3IR
OUT2IR
OUT1IR
OUT0IR
USBIRQ
USB Interrupt Request
7FAB
b7
b6
b5
b4
b3
b2
b1
b0
-
-
-
USESIR
SUSPIR
SUTOKIR
SOFIR
SUDAVIR
IN07IEN
Endpoints 0-7 IN Interrupt Enables
7FAC
b7
b6
b5
b4
b3
b2
b1
b0
IN7IEN
IN6IEN
IN5IEN
IN4IEN
IN3IEN
IN2IEN
IN1IEN
IN0IEN
OUT07IEN
Endpoints 0-7 OUT Interrupt Enables
7FAD
b7
b6
b5
b4
b3
b2
b1
b0
OUT7IEN
OUT6IEN
OUT5IEN
OUT4IEN
OUT3IEN
OUT2IEN
OUT1IEN
OUT0IEN
USBIEN
USB Interrupt Enables
7FAE
b7
b6
b5
b4
b3
b2
b1
b0
-
-
-
URESIE
SUSPIE
SUTOKIE
SOFIE
SUDAVIE
Figure 9-4. EZ-USB Interrupt Registers
Figure 9-4 shows the registers associated with the USB interrupts. Each interrupt source has an
enable (IEN) and a request (IRQ) bit. The 8051 sets the IEN bit to enable the interrupt. The USB
core sets an IRQ bit high to request an interrupt, and the 8051 clears an IRQ bit by writing a “1” to
it.
Chapter 9. EZ-USB Interrupts
Page 9-7
EZ-USB Technical Reference Manual
The USBIEN and USBIRQ registers control the first five interrupts shown in Figure 9-2. The
IN07IEN and OUT07 registers control the remaining 16 USB interrupts, which correspond to the
16 bulk endpoints IN0-IN7 and OUT0-OUT7.
The 21 USB interrupts are now described in detail.
9.5
SUTOK, SUDAV Interrupts
SETUP Stage
S
A E C
E
D N R
T
D D C
U
R P 5
P
Token Packet
D
A
T
A
0
8 bytes
Setup
Data
C
R
C
1
6
Data Packet
SUTOK
Interrupt
A
C
K
H/S Pkt
SUDAV
Interrupt
Figure 9-5. SUTOK and SUDAV Interrupts
SUTOK and SUDAV are supplied to the 8051 by EZ-USB CONTROL endpoint zero. The first portion of a USB CONTROL transfer is the SETUP stage shown in Figure 9-5. (A full CONTROL
transfer is the SETUP stage shown in Figure 7-1.) When the EZ-USB core decodes a SETUP
packet, it asserts the SUTOK (SETUP Token) interrupt request. After the EZ-USB core has
received the eight bytes error-free and copied them into eight internal registers at SETUPDAT, it
asserts the SUDAV interrupt request.
The 8051 program responds to the SUDAV interrupt by reading the eight SETUP data bytes in
order to decode the USB request (Chapter 7, "EZ-USB Endpoint Zero").
The SUTOK interrupt is provided to give advance warning that the eight register bytes at SETUPDAT are about to be over-written. It is useful for debug and diagnostic purposes.
9.6
SOF Interrupt
F C
S
R R
O
N C
F
O 5
Token Pkt
Figure 9-6. A Start Of Frame (SOF) Packet
Page 9-8
EZ-USB Technical Reference Manual v1.10
USB Start of Frame interrupt requests occur every millisecond. When the EZ-USB core receives
an SOF packet, it copies the eleven-bit frame number (FRNO in Figure 9-6) into the USBFRAMEH
and USBFRAMEL registers, and activates the SOF interrupt request. The 8051 services all isochronous endpoint data as a result of the SOF interrupt.
9.7
Suspend Interrupt
If the EZ-USB detects 3 ms of no bus activity, it activates the SUSP (Suspend) interrupt request. A
full description of Suspend-Resume signaling appears in Chapter 11, "EZ-USB Power Management."
9.8
USB RESET Interrupt
The USB signals a bus reset by driving both D+ and D- low for at least 10 ms. When the EZ-USB
core detects the onset of USB bus reset, it activates the URES interrupt request.
9.9
Bulk Endpoint Interrupts
The remaining 16 USB interrupt requests are indexed to the 16 EZ-USB bulk endpoints. The EZUSB core activates a bulk interrupt request when the endpoint buffer requires service. For an OUT
endpoint, the interrupt request signifies that OUT data has been sent from the host, validated by
the EZ-USB core, and is sitting in the endpoint buffer memory. For an IN endpoint, the interrupt
request signifies that the data previously loaded by the 8051 into the IN endpoint buffer has been
read and validated by the host, making the IN endpoint buffer ready to accept new data.
The EZ-USB core sets an endpoint’s interrupt request bit when the endpoint’s busy bit (in the endpoint CS register) goes low, indicating that the endpoint buffer is available to the 8051. For example, when endpoint 4-OUT receives a data packet, the busy bit in the OUT4CS register goes low,
and OUT07IRQ.4 goes high, requesting the endpoint 4-OUT interrupt.
9.10
USB Autovectors
The USB interrupt is shared by 21 interrupt sources. To save the code and processing time
required to sort out which USB interrupt occurred, the EZ-USB core provides a second level of
interrupt vectoring, called “Autovectoring.” When the 8051 takes a USB interrupt, it pushes the
program counter onto its stack, and then executes a jump to address 43, where it expects to find a
jump instruction to an interrupt service routine. The 8051 jump instruction is encoded as follows:
Chapter 9. EZ-USB Interrupts
Page 9-9
EZ-USB Technical Reference Manual
Table 9-2. 8051 JUMP Instruction
Address Op-Code Hex Value
0043
Jump
0x02
0044
AddrH
0xHH
0045
AddrL
0xLL
If Autovectoring is enabled (AVEN=1 in the USBBAV register), the EZ-USB core substitutes its
AVEC byte for the byte at address 0x0045. Therefore, if the programmer pre-loads the high byte
(“page”) of a jump table address at location 0x0044, the core-inserted byte at 0x45 will automatically direct the JUMP to one of 21 addresses within the page. In the jump table, the programmer
then puts a series of jump instructions to each particular ISR.
Table 9-3. A Typical USB Jump Table
Table Offset
Page 9-10
Instruction
00
JMP SUDAV_ISR
04
JMP SOF_ISR
08
JMP SUTOK_ISR
0C
JMP SUSPEND_ISR
10
JMP USBRESET_ISR
14
JMP IBN_ISR (2122/2126 only,
otherwise NOP)
18
JMP EP0IN _ISR
1C
JMP EP0OUT_ISR
20
JMP IN1BUF_ISR
24
JMP EP1OUT_ISR
28
JMP EP2IN_ISR
2C
JMP EP2OUT_ISR
30
JMP EP3IN_ISR
34
JMP EP3OUT_ISR
38
JMP EP4IN_ISR
3C
JMP EP4OUT_ISR
40
JMP EP5IN_ISR
44
JMP EP5OUT_ISR
48
JMP EP6IN_ISR
4C
JMP EP6OUT_ISR
50
JMP EP7IN_ISR
54
JMP EP7OUT_ISR
EZ-USB Technical Reference Manual v1.10
9.11
Autovector Coding
A detailed example of a program that uses Autovectoring is presented in Section 6.14, "Interrupt
Bulk Transfer Example." The coding steps are summarized here. To employ EZ-USB Autovectoring:
1. Insert a jump instruction at 0x43 to a table of jump instructions to the various USB interrupt
service routines.
2. Code the jump table with jump instructions to each individual USB interrupt service routine.
This table has two important requirements, arising from the format of the AVEC byte (zerobased, with 2 LSBs set to 0):
•It must begin on a page boundary (address 0xNN00).
•The jump instructions must be four bytes apart.
•The interrupt service routines can be placed anywhere in memory.
•Write initialization code to enable the USB interrupt (INT2), and Autovectoring.
8051 USB
Interrupt
Vector
0043
0044
0045
USB_Jmp_Table:
0400
LJMP
04
(00)2C
USB core
AVEC
2C
042C
042D
042E
LJMP EP2OUT_ISR
01
EP2OUT_ISR:
19
0119
Figure 9-7. The Autovector Mechanism in Action
Figure 9-7 illustrates an ISR that services endpoint 2-OUT. When endpoint 2-OUT requires service, the EZ-USB core activates the USB interrupt request, vectoring the 8051 to location 0x43.
The jump instruction at this location, which was originally coded as “LJMP 04-00” becomes “LJMP
04-2C” due to the EZ-USB core substituting 2C as the Autovector byte for Endpoint 2-OUT
(Table 9-3). The 8051 jumps to 042C, where it executes the jump instruction to the endpoint 2OUT ISR shown in this example at address 0119. Once the 8051 takes the vector at 0043, initiation of the endpoint-specific ISR takes only eight 8051 cycles.
Chapter 9. EZ-USB Interrupts
Page 9-11
EZ-USB Technical Reference Manual
9.12
I2C Interrupt
EZ-USB 8051
EIE.1
DONE
RD or WR
I2DAT register
S
S
R
R
8051
I2C-compatible
Interrupt (INT3)
EXIF.5(rd)
I2C-compatible
EXIF.5(0)
Interrupt Request
I2CS
I2DAT
START
STOP
LASTRD
ID1
ID0
BERR
ACK
DONE
D7
D6
D5
D4
D3
D2
D1
D0
Figure 9-8. I2C Interrupt Enable Bits and Registers
Chapter 4, "EZ-USB Input/Output" describes the 8051 interface to the EZ-USB I2C controller. The
8051 uses two registers, I2CS (I2C Control and Status) and I2DAT (I2C Data) to transfer data over
the I2C bus. The EZ-USB core signals completion of a byte transfer by setting the DONE bit
(I2CS.0) high, which also sets an I2C interrupt request latch (Figure 9-8). This interrupt request is
routed to the 8051 INT3 interrupt.
The 8051 enables the I2C interrupt by setting EIE.1=1. The 8051 determines the state of the interrupt request flag by reading EXIF.5, and resets the INT3 interrupt request by writing a zero to
EXIF.5. Any 8051 read or write to the I2DAT or I2CS register automatically clears the I2C interrupt
request.
Page 9-12
EZ-USB Technical Reference Manual v1.10
9.13
I2C Registers
I2CS
7FA5
I2C Control and Status
b7
b6
b5
b4
b3
b2
b1
b0
START
STOP
LASTRD
ID1
ID0
BERR
ACK
DONE
R/W
R/W
R/W
R
R
R
R
R
0
0
0
X
X
0
0
0
Figure 9-9. I2C Control and Status Register
I2DAT
7FA6
I2C Data
b7
b6
b5
b4
b3
b2
b1
b0
D7
D6
D5
D4
D3
D2
D1
D0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
x
x
x
x
x
x
x
x
Figure 9-10. I2C Data
The two registers that the 8051 uses to control I2C transfers are shown above. In the EZ-USB
family, an I2C interrupt request occurs on INT3 whenever the DONE bit (I2CS.0) makes a 0-to-1
transition. This interrupt signals the 8051 that the I2C controller is ready for another command.
The 8051 concludes I2C transfers by setting the STOP bit (I2CS.6). When the STOP condition has
been sent over the I2C bus, the I2C controller resets I2CS.6 to zero. During the time the I2C controller is generating the stop condition, it ignores accesses to the I2CS and I2DAT registers. The
8051 code should therefore check the STOP bit for zero before writing new data to I2CS or I2DAT.
In the EZ-USB family, it does this by polling the I2CS.6 bit.
Chapter 9. EZ-USB Interrupts
Page 9-13
EZ-USB Technical Reference Manual
Page 9-14
EZ-USB Technical Reference Manual v1.10
Chapter 10 EZ-USB Resets
10.1
Introduction
The EZ-USB chip has three resets:
•
A Power-On Reset (POR), which turns on the EZ-USB chip in a known state.
•
An 8051 reset, controlled by the EZ-USB core.
•
A USB bus reset, sent by the host to reset a device.
This chapter describes the effects of these three resets.
10.2
EZ-USB Power-On Reset (POR)
RES
8051
Vcc
CPUCS.0
(1 at PWR ON)
RESET
RES
EZ-USB Core
24 MHz
USB Bus
Reset
48 MHz
XIN
12
MHz
Oscillator
PLL
XOUT
÷2
CLK24
Figure 10-1. EZ-USB Resets
Chapter 10. EZ-USB Resets
Page 10-1
EZ-USB Technical Reference Manual
When power is first applied to the EZ-USB chip, the external R-C circuit holds the EZ-USB core in
reset until the on-chip PLL stabilizes. The CLK24 pin is active as soon as power is applied. The
8051 may clear an EZ-USB control bit, CLK24OE, to inhibit the CLK24 output pin for EMI-sensitive
applications that do not need this signal. External logic can force a chip reset by pulling the
RESET pin HI. The RESET pin is normally connected to Vcc through a 1 µF capacitor and to GND
through a 10-K resistor (Figure 10-1). The oscillator and PLL are unaffected by the state of the
RESET pin.
The CLK24 signal is active while RESET = HI. When RESET returns LO, the activity on the
CLK24 pin depends on whether or not the EZ-USB chip is in suspend state. If in suspend, CLK24
stops. Resumption of USB bus activity or asserting the WAKEUP# pin LO re-starts the CLK24 signal.
Power-on default values for all EZ-USB register bits are shown in Chapter 12, "EZ-USB Registers." Table 10-1 summarizes reset states that affect USB device operation. Note that the term
“Power-On Reset” refers to a reset initiated by application of power, or by assertion of the RESET
pin.
Table 10-1. EZ-USB States After Power-On Reset (POR)
Item
Register
Default Value
Comment
1
Endpoint Data
xxxxxxxx
2
Byte Counts
xxxxxxxx
3
CPUCS
rrrr0011
rrrr=rev number, b1 =CLK24OE, b0=8051RES
4
PORT Configs
00000000
IO, not alternate functions
5
PORT Registers
xxxxxxxx
6
PORT OEs
00000000
Inputs
7
Interrupt Enables
00000000
Disabled
8
Interrupt Reqs
00000000
Cleared
9
Bulk IN C/S
00000000
Bulk IN endpoints not busy (unarmed)
10
Bulk OUT C/S*
00000000
Bulk OUT endpoints not busy (unarmed)
11
Toggle Bits
00000000
Data toggles = 0
12
USBCS
00000100
RENUM=0, DISCOE=1 (Discon pin drives)
13
FNADDR
00000000
USB Function Address
14
IN07VAL
01010111
EP0,1,2,4,6 IN valid
15
OUT07VAL
01010101
EP0,2,4,6 OUT valid
16
INISOVAL
00000111
EP8,9,10 IN valid
17
OUTISOVAL
00000111
EP8,910OUT valid
18
USBPAIR
0x000000
ISOsend0 (b7) = 0, no pairing
19
USBBAV
00000000
Break condition cleared, no Autovector
20
Configuration
0
Internal EZ-USB core value
21
Alternate Setting
0
Internal EZ-USB core value
* When the 8051 is released from reset, the EZ-USB automatically arms the Bulk OUT endpoints
by setting their CS registers to 000000010b.
Page 10-2
EZ-USB Technical Reference Manual v1.10
From Table 10-1, at power-on:
•
Endpoint data buffers and byte counts are un-initialized (1,2).
•
The 8051 is held in reset, and the CLK24 pin is enabled (3).
•
All port pins are configured as input ports (4-6).
•
USB interrupts are disabled, and USB interrupt requests are cleared (7-8).
•
Bulk IN and OUT endpoints are unarmed, and their stall bits are cleared (9). The EZ-USB
core will NAK IN or OUT tokens while the 8051 is reset. OUT endpoints are enabled when
the 8051 is released from reset.
•
Endpoint toggle bits are cleared (11).
•
The ReNum bit is cleared. This means that the EZ-USB core, and not the 8051, initially
responds to USB device requests (12).
•
The USB function address register is set to zero (13).
•
The endpoint valid bits are set to match the endpoints used by the default USB device (1417).
•
Endpoint pairing is disabled. Also, ISOSend0=0, meaning that if an Isochronous endpoint
receives an IN token without being loaded by the 8051 in the previous frame, the EZ-USB
core does not generate any response (18).
•
The breakpoint condition is cleared, and autovectoring is turned off (19).
•
Configuration Zero, Alternate Setting Zero is in effect (20-21).
10.3
Releasing the 8051 Reset
The EZ-USB register bit CPUCS.0 resets the 8051. This bit is HI at power-on, initially holding the
8051 in reset. There are three ways to release the 8051 from reset:
•
By the host, as the final step of a RAM download.
•
Automatically, as part of an EEPROM load.
•
Automatically, when external ROM is used (EA=1).
Chapter 10. EZ-USB Resets
Page 10-3
EZ-USB Technical Reference Manual
10.3.1 RAM Download
Once enumerated, the host can download code into the EZ-USB RAM using the “Firmware Load”
vendor request (Chapter 7, "EZ-USB Endpoint Zero"). The last packet loaded writes 0 to the
CPUCS register, which clears the 8051 RESET bit.
Note
The other bit in the CPUCS register, CLK24OE, is writable only by the 8051, so the host writing a
zero byte to this register does not turn off the CLK24 signal.
10.3.2 EEPROM Load
Chapter 5 describes the EEPROM boot loads in detail. Briefly, at power-on, the EZ-USB core
checks for the presence of an EEPROM on its I2C bus. If found, it reads the first EEPROM byte. If
it reads 0xB2 as the first byte, the EZ-USB core downloads 8051 code from the EEPROM into
internal RAM. The last byte of a “B2” load writes 0x00 to the CPUCS register (at 0x7F92), which
releases the 8051 from reset.
10.3.3 External ROM
EZ-USB systems can use external program memory containing 8051 code and USB device
descriptors, which include the VID/DID/PID bytes. Because these systems do no require and I2C
EEPROM to supply the VID/DID/PID, the EZ-USB core automatically releases 8051 reset when:
1. EA=1 (External code memory), and
2. No “B0/B2” EEPROM is detected on the I2C bus.
The EZ-USB core also sets the ReNum bit to “1,” giving USB control to the 8051.
10.4
8051 Reset Effects
Once the 8051 is running, the USB host may reset the 8051 by downloading the value 0x01 to the
CPUCS register. The host might do this in preparation for loading code overlays, effectively magnifying the size of the internal EZ-USB RAM. For such applications it is important to know the
state of the EZ-USB chip during and after an 8051 reset. In this section, this particular reset is
called an “8051 Reset,” and should not be confused with the POR described in Section 10.2, "EZUSB Power-On Reset (POR)." This discussion applies only to the condition where the EZ-USB
chip is powered, and the 8051 is reset by the host setting the CPUCS register to 0.
Page 10-4
EZ-USB Technical Reference Manual v1.10
The basic USB device configuration remains intact through an 8051 reset. Valid endpoints remain
valid, the USB function address remains the same, and the IO ports retain their configurations and
values. Stalled endpoints remain stalled, and data toggles don’t change. The only effects of an
8051 reset are as follows:
•
USB interrupts are disabled, but pending interrupt requests remain pending.
•
During the 8051 Reset, all bulk endpoints are unarmed, causing the EZ-USB core to NAK
and IN or OUT tokens.
•
After the 8051 Reset is removed, the OUT bulk endpoints are automatically armed. OUT
endpoints are thus ready to accept one OUT packet before 8051 intervention is required.
•
The breakpoint condition is cleared.
The ReNum bit is not affected by an 8051 reset.
When the 8051 comes out of reset, the pending interrupts are kept pending, but disabled (1). This
gives the firmware writer the choice of acting on pre-8051-reset USB events, or ignoring them by
clearing the pending interrupt(s).
During the 8051 reset time, the EZ-USB core holds off any USB traffic by NAKing IN and OUT
tokens (2). The EZ-USB core automatically arms the OUT endpoints when the 8051 exits the
reset state (3).
USBBAV.3, the breakpoint BREAK bit, is cleared (4). The other bits in the USBBAV register are
unaffected.
Chapter 10. EZ-USB Resets
Page 10-5
EZ-USB Technical Reference Manual
10.5
USB Bus Reset
The host signals a USB Bus Reset by driving an SE0 state (both D+ and D- data lines low) for a
minimum of 10 ms. The EZ-USB core senses this condition, requests the 8051 USB Interrupt
(INT2), and supplies the interrupt vector for a USB Reset. A USB reset affects the EZ-USB
resources as shown in Table 10-2.
Table 10-2. EZ-USB States After a USB Bus Reset
Item
Register
Default Value
Comment
1
Endpt Data
uuuuuuuu
u = unchanged
2
Byte Counts
uuuuuuuu
3
CPUCS
uuuuuuuu
4
PORT Configs
uuuuuuuu
5
PORT Registers
uuuuuuuu
6
PORT OEs
uuuuuuuu
7
Interrupt Enables
uuuuuuuu
8
Interrupt Reqs
uuuuuuuu
9
Bulk IN C/S
00000000
unarm
10
Bulk OUT C/S
uuuuuuuu
retain armed/unarmed state
11
Toggle Bits
00000000
12
USBCS
uuuuuuuu
ReNum bit unchanged
13
FNADDR
00000000
USB Function Address
14
IN07VAL
uuuuuuuu
15
OUT07VAL
uuuuuuuu
16
INISOVAL
uuuuuuuu
17
OUTISOVAL
uuuuuuuu
18
USBPAIR
uuuuuuuu
19
Configuration
0
20
Alternate Setting
0
A USB bus reset leaves most EZ-USB resources unchanged. From Table 10-2, after USB bus
reset:
•
The EZ-USB core unarms all Bulk IN endpoints (9). Data loaded by the 8051 into an IN
endpoint buffer remains there, and the 8051 firmware can either re-send it by loading the
endpoint byte count register to re-arm the transfer, or send new data by re-loading the IN
buffer before re-arming the endpoint.
•
Bulk OUT endpoints retain their busy states (10). Data sent by the host to an OUT endpoint buffer remains in the buffer, and the 8051 firmware can either read the data or reject
Page 10-6
EZ-USB Technical Reference Manual v1.10
it as stale simply by not reading it. In either case, the 8051 loads a dummy value to the
endpoint byte count register to re-arm OUT transfers.
•
Toggle bits are cleared (11).
•
The device address is reset to zero (13).
Note from item 12 that the ReNum bit is unchanged after a USB bus reset. Therefore, if a device
has ReNumerated and loaded a new personality, it retains the new personality through a USB
bus reset.
10.6
EZ-USB Disconnect
Table 10-3. Effects of an EZ-USB Disconnect and Re-connect
Item
Register
Default Value
Comment
1
Endpt Data
uuuuuuuu
u = unchanged
2
Byte Counts
uuuuuuuu
3
CPUCS
uuuuuuuu
4
PORT Configs
uuuuuuuu
5
PORT Registers
uuuuuuuu
6
PORT OEs
uuuuuuuu
7
Interrupt Enables
uuuuuuuu
8
Interrupt Reqs
uuuuuuuu
9
Bulk IN C/S
00000000
unarm, clear stall bit
10
Bulk OUT C/S
00000000
Arm, clear stall bit
11
Toggle Bits
00000000
reset
12
USBCS
uuuuuuuu
ReNum bit unchanged
13
FNADDR
00000000
USB Function Address
14
IN07VAL
uuuuuuuu
15
OUT07VAL
uuuuuuuu
16
INISOVAL
uuuuuuuu
17
OUTISOVAL
uuuuuuuu
18
USBPAIR
uuuuuuuu
19
Configuration
0
20
Alternate Setting
0
Although not strictly a “reset,” when the EZ-USB simulates a disconnect-reconnect in order to
ReNumerate, there are effects on the EZ-USB core:
•
Bulk IN endpoints are unarmed, and bulk OUT endpoints are armed (9-10).
Chapter 10. EZ-USB Resets
Page 10-7
EZ-USB Technical Reference Manual
•
Endpoint STALL bits are cleared (9-10).
•
Data toggles are reset (11).
•
The function address is reset to zero (13).
•
The configuration is reset to zero (19).
•
Alternate settings are reset to zero (20).
10.7
Reset Summary
Table 10-4. Effects of Various EZ-USB Resets (“U” Means “Unaffected”)
Resource
RESET pin
USB Bus Reset
Disconnect
8051 Reset
reset
U
U
N/A
EP0-7 IN EPs
unarm
unarm
unarm
unarm
EP0-7 OUT EPs
unarm
U
arm
unarm/arm
8051 Reset
Breakpoint
reset
U
U
reset
Stall Bits
reset
U
reset
U
Interrupt Enables
reset
U
U
reset
Interrupt Reqs
reset
U
U
U
CLK24
run
U
U
U
Data Toggles
reset
reset
reset
U
Function Address
reset
reset
reset
U
Configuration
0
0
0
U
ReNum
0
U
U
U
Table 10-4 summarizes the effects of the four EZ-USB resets.
Note
The I2C controller is not reset for any of the conditions laid out in Table 10-4. Only the EZ-USB
RESET pin resets it.
Page 10-8
EZ-USB Technical Reference Manual v1.10
Chapter 11 EZ-USB Power Management
11.1
Introduction
The USB host can suspend a device to put it into a power-down mode. When the USB signals a
SUSPEND operation, the EZ-USB chip goes through a sequence of steps to allow the 8051 to first
turn off external power-consuming subsystems, and then enter an ultra-low-power mode by turning
off its oscillator. Once suspended, the EZ-USB chip is awakened either by resumption of USB bus
activity, or by assertion of its WAKEUP# pin. This chapter describes the suspend-resume mechanism.
12 MHz
WAKEUP pin
USB Resume
START
STOP
Oscillator
PLL
48 MHz
Restart
Delay
div by
2
CLK24
PCON.0
Resume INT
No USB activity
for 3 msec.
8051
Signal
Resume
(USBCS.0)
USB
"SUSPEND"
Interrupt
Figure 11-1. Suspend-Resume Control
Chapter 11. EZ-USB Power Management
Page 11-1
EZ-USB Technical Reference Manual
Figure 11-1 illustrates the EZ-USB logic that implements USB suspend and resume. These operations are explained in the next sections.
11.2
Suspend
12 MHz
STOP
Oscillator
PLL
48 MHz
div by
2
CLK24
PCON.0
8051
INT2
No USB activity
for 3 msec.
USB
"SUSPEND"
Interrupt
Figure 11-2. EZ-USB Suspend Sequence
A USB device recognizes SUSPEND as 3 ms of a bus idle (“J”) state. The EZ-USB core alerts the
8051 by asserting the USB (INT2) interrupt and the SUSPEND interrupt vector. This gives the
8051 code a chance to perform power conservation housekeeping before shutting down the oscillator.
Page 11-2
EZ-USB Technical Reference Manual v1.10
The 8051 code responds to the SUSPEND interrupt by taking the following steps:
1. Performs any necessary housekeeping such as shutting off external power-consuming
devices.
2. Sets bit 0 of the PCON SFR (Special Function Register). This has two effects:
•
The 8051 enters its idle mode, which is exited by any interrupt.
•
The 8051 sends an internal signal to the EZ-USB core which causes it to turn off the
oscillator and PLL.
These actions put the EZ-USB chip into a low-power mode, as required by the USB Specification.
11.3
Resume
12 MHz
WAKEUP# pin
USB Resume
START
Oscillator
PLL
48 MHz
Restart
Delay
div by
2
CLK24
Resume INT
8051
Signal
Resume
(USBCS.0)
Figure 11-3. EZ-USB Resume Sequence
Chapter 11. EZ-USB Power Management
Page 11-3
EZ-USB Technical Reference Manual
The EZ-USB oscillator re-starts when:
•
USB bus activity resumes (shown as “USB Resume” in Figure 11-3), or
•
External logic asserts the EZ-USB WAKEUP# pin low.
After an oscillator stabilization time, the EZ-USB core asserts the 8051 Resume interrupt
(Figure 9-1). This causes the 8051 to exit its idle mode. The Resume interrupt is the highest priority 8051 interrupt. It is always enabled, unaffected by the EA bit.
The resume ISR clears the interrupt request flag, and executes an “reti” (return from interrupt)
instruction. This causes the 8051 to continue program execution at the instruction following the
one that set PCON.0 to initiate the suspend operation.
About the ‘Resume’ Interrupt
The 8051 enters the idle mode when PCON.0 is set to “1.” Although the 8051 exits its idle state
when any interrupt occurs, the EZ-USB logic supports only the RESUME interrupt for the USB
resume operation. This is because the EZ-USB core asserts this particular interrupt after restarting the 8051 clock.
11.4
Remote Wakeup
USBCS
USB Control and Status
7FD6
b7
b6
b5
b4
b3
b2
b1
b0
WAKESRC
-
-
-
DISCON
DISCOE
RENUM
SIGRSUME
Figure 11-4. USB Control and Status Register
Two bits in the USBCS register are used for remote wakeup, WAKESRC and SIGRSUME.
After exiting the idle state, the 8051 reads the WAKESRC bit in the USBCS register to discover
how the wakeup was initiated. WAKESRC=1 indicates assertion of the WAKEUP# pin, and
WAKESRC=0 indicates a resumption of USB bus activity. The 8051 clears the WAKESRC bit by
writing a “1” to it.
Note
If your design does not use remote wakeup, tie the WAKEUP# pin high. Holding the WAKEUP#
pin low inhibits the EZ-USB chip from suspending.
Page 11-4
EZ-USB Technical Reference Manual v1.10
When a USB device is suspended, the hub driver is tri-stated, and the bus pullup and pulldown
resistors cause the bus to assume the “J,” or idle state. A suspended device signals a remote
wakeup by asserting the “K” state for 10-15 ms. The 8051 controls this using the SIGRSUME bit in
the USBCS register.
If the 8051 finds WAKESRC=1 after exiting the idle mode, it drives the “K” state for 10-15 ms to
signal the USB remote wakeup. It does this by setting SIGRSUME=1, waiting 10-15 ms, and then
setting SIGRSUME=0. When SIGRSUME=0, the EZ-USB bus buffer reverts to normal operation.
The resume routine should also write a “1” to the WAKESRC bit to clear it.
J and K States
The USB Specification uses differential data signals D+ and D-. Instead of defining a logical “1”
and “0,” it defines the “J” and “K” states. For a high speed device, the “J” state means (D+ > D-).
The USB Default device does not support remote wakeup. This fact is reported at enumeration
time in byte 7 of the built-in Configuration Descriptor (Table 5-10).
Remote Wakeup: The Big Picture
Additional factors besides the EZ-USB suspend-resume mechanism described in this section
determine whether remote wakeup is possible. These are:
1.
The device must report that it is capable of signaling a remote wakeup in the “bAttributes”
field of its Configuration Descriptor. See Table 5-10 for an example of this descriptor.
2.
The host must issue a “Set_Feature/Device” request with the feature selector field set to
0x01 to enable remote wakeup. See Table 7-6 for the detailed request.
Chapter 11. EZ-USB Power Management
Page 11-5
EZ-USB Technical Reference Manual
Page 11-6
EZ-USB Technical Reference Manual v1.10
Chapter 12 EZ-USB Registers
12.1
Introduction
This section describes the EZ-USB registers in the order they appear in the EZ-USB memory map.
The registers are named according to the following conventions.
Most registers deal with endpoints. The general register format is DDDnFFF, where:
DDD
is endpoint direction, IN or OUT with respect to the USB host.
n
is the endpoint number, where:
FFF
•
“07” refers to endpoints 0-7 as a group.
•
0-7 refers to each individual BULK/INTERRUPT/CONTROL endpoint.
•
“ISO” indicates isochronous endpoints as a group.
is the function, where:
•
CS is a control and status register
•
IRQ is an Interrupt Request bit
•
IE is an Interrupt Enable bit
•
BC, BCL, and BCH are byte count registers. BC is used for single byte counts, and
BCL/H are used as the low and high bytes of 16-bit byte counts.
•
DATA is a single-register access to a FIFO.
•
BUF is the start address of a buffer.
Examples:
•
IN7BC is the Endpoint 7 IN byte count.
•
OUT07IRQ is the register containing interrupt request bits for OUT endpoints 0-7.
Chapter 12. EZ-USB Registers
Page 12-1
EZ-USB Technical Reference Manual
•
INISOVAL contains valid bits for the isochronous IN endpoints (EP8IN-EP15IN).
Other Conventions
USB
Indicates a global (not endpoint-specific) USB function.
ADDR
Is an address.
VAL
Means “valid.”
FRAME
Is a frame count.
PTR
Is an address pointer.
Register Name
Register Function
Address
b7
b6
b5
b4
b3
b2
b1
b0
bitname
bitname
bitname
bitname
bitname
bitname
bitname
bitname
R, W access
R, W access
R, W access
R, W access
R, W access
R, W access
R, W access
R, W access
Default val
Default val
Default val
Default val
Default val
Default val
Default val
Default val
Figure 12-1. Register Description Format
Figure 12-1 illustrates the register description format used in this chapter.
•
The top line shows the register name, functional description, and address in the EZ-USB
memory.
•
The second line shows the bit position in the register.
•
The third line shows the name of each bit in the register.
•
The fourth line shows 8051 accessibility: R(ead), W(rite), or R/W.
•
The fifth line shows the default value. These values apply after a Power-On-Reset (POR).
Page 12-2
EZ-USB Technical Reference Manual v1.10
12.2
Bulk Data Buffers
INnBUF,OUTnBUF
Endpoint 0-7 IN/OUT Data Buffers
1B40-1F3F*
b7
b6
b5
b4
b3
b2
b1
b0
D7
D6
D5
D4
D3
D2
D1
D0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
x
x
x
x
x
x
x
x
* See Table 12-1 for individual endpoint buffer addresses.
Figure 12-2. Bulk Data Buffers
Table 12-1. Bulk Endpoint Buffer Memory Addresses
Address
Address
Name
Size
1F00-1F3F
7F00-7F3F
IN0BUF
64
1EC0-1EFF
7EC0-7EFF
OUT0BUF
64
1E80-1EBF
7E80-7EBF
IN1BUF
64
1E40-1E7F
7E40-7E7F
OUT1BUF
64
1E00-1E3F
7E00-7E3F
IN2BUF
64
1DC0-1DFF
7DC0-7DFF
OUT2BUF
64
1D80-1DBF
7D80-7DBF
IN3BUF
64
1D40-1D7F
7D40-7D7F
OUT3BUF
64
1D00-1D3F
7D00-7D3F
IN4BUF
64
1CC0-1CFF
7CC0-7CFF
OUT4BUF
64
1C80-1CBF
7C80-7CBF
IN5BUF
64
1C40-1C7F
7C40-7C7F
OUT5BUF
64
1C00-1C3F
7C00-7C3F
IN6BUF
64
1BC0-1BFF
7BC0-7BFF
OUT6BUF
64
1B80-1BBF
7B80-7BBF
IN7BUF
64
1B40-1B7F
7B40-7B7F
OUT7BUF
64
Sixteen 64-byte bulk data buffers appear at 0x1B40 and 0x7B40 in the 8K version of EZ-USB, and
only at 0x7B40 in the 32K version of EZ-USB. The endpoints are ordered to permit the reuse of
the buffer space as contiguous RAM when the higher numbered endpoints are not used. These
registers default to unknown states.
Chapter 12. EZ-USB Registers
Page 12-3
EZ-USB Technical Reference Manual
12.3
Isochronous Data FIFOs
OUTnDATA
EP8OUT-EP15OUT FIFO Registers
7F60-7F67*
b7
b6
b5
b4
b3
b2
b1
b0
D7
D6
D5
D4
D3
D2
D1
D0
R
R
R
R
R
R
R
R
x
x
x
x
x
x
x
x
INnDATA
EP8IN-EP15IN FIFO Registers
7F68-7F6F*
b7
b6
b5
b4
b3
b2
b1
b0
D7
D6
D5
D4
D3
D2
D1
D0
W
W
W
W
W
W
W
W
x
x
x
x
x
x
x
x
* See Table 12-2 for individual endpoint buffer addresses.
Figure 12-3. Isochronous Data FIFOs
Table 12-2. Isochronous Endpoint FIFO Register Addresses
Address
Isochronous Data
Name
7F60
Endpoint 8 OUT Data
OUT8DATA
7F61
Endpoint 9 OUT Data
OUT9DATA
7F62
Endpoint 10 OUT Data
OUT10DATA
7F63
Endpoint 11 OUT Data
OUT11DATA
7F64
Endpoint 12 OUT Data
OUT12DATA
7F65
Endpoint 13 OUT Data
OUT13DATA
7F66
Endpoint 14 OUT Data
OUT14DATA
7F67
Endpoint 15 OUT Data
OUT15DATA
7F68
Endpoint 8 IN Data
IN8DATA
7F69
Endpoint 9 IN Data
IN9DATA
7F6A
Endpoint 10 IN Data
IN10DATA
7F6B
Endpoint 11 IN Data
IN11DATA
7F6C
Endpoint 12 IN Data
IN12DATA
7F6D
Endpoint 13 IN Data
IN13DATA
7F6E
Endpoint 14 IN Data
IN14DATA
7F6F
Endpoint 15 IN Data
IN15DATA
Sixteen addressable data registers hold data from the eight isochronous IN endpoints and the
eight isochronous OUT endpoints. Reading a Data Register reads a Receive FIFO byte (USB
OUT data); writing a Data Register loads a Transmit FIFO byte (USB IN data).
Page 12-4
EZ-USB Technical Reference Manual v1.10
12.4
Isochronous Byte Counts
OUTnBCH
OUT(8-15) Byte Count High
7F70-7F7F*
b7
b6
b5
b4
b3
b2
b1
b0
0
0
0
0
0
0
BC9
BC8
R
R
R
R
R
R
R
R
x
x
x
x
x
x
x
x
OUTnBCL
OUT(8-15) Byte Count Low
7F70-7F7F*
b7
b6
b5
b4
b3
b2
b1
b0
BC7
BC6
BC5
BC4
BC3
BC2
BC1
BC0
R
R
R
R
R
R
R
R
x
x
x
x
x
x
x
x
* See Table 12-3 for individual endpoint buffer addresses.
Figure 12-4. Isochronous Byte Counts
Table 12-3. Isochronous Endpoint Byte Count Register Addresses
Address
Isochronous Data
Name
7F70
Endpoint 8 Byte Count High
OUT8BCH
7F71
Endpoint 8 Byte Count Low
OUT8BCL
7F72
Endpoint 9 Byte Count High
OUT9BCH
7F73
Endpoint 9 Byte Count Low
OUT9BCL
7F74
Endpoint 10 Byte Count High
OUT10BCH
7F75
Endpoint 10 Byte Count Low
OUT10BCL
7F76
Endpoint 11 Byte Count High
OUT11BCH
7F77
Endpoint 11 Byte Count Low
OUT11BCL
7F78
Endpoint 12 Byte Count High
OUT12BCH
7F79
Endpoint 12 Byte Count Low
OUT12BCL
7F7A
Endpoint 13 Byte Count High
OUT13BCH
7F7B
Endpoint 13 Byte Count Low
OUT13BCL
7F7C
Endpoint 14 Byte Count High
OUT14BCH
7F7D
Endpoint 14 Byte Count Low
OUT14BCL
7F7E
Endpoint 15 Byte Count High
OUT15BCH
7F7F
Endpoint 15 Byte Count Low
OUT15BCL
Chapter 12. EZ-USB Registers
Page 12-5
EZ-USB Technical Reference Manual
The EZ-USB core uses the byte count registers to report isochronous data payload sizes for OUT
data transferred from the host to the USB core. Ten bits of byte count data allow payload sizes up
to 1,023 bytes. A byte count of zero is valid, meaning that the host sent no isochronous data during the previous frame. The default values of these registers are unknown.
Byte counts are valid only for OUT endpoints. The byte counts indicate the number of bytes
remaining in the endpoint’s Receive FIFO. Every time the 8051 reads a byte from the ISODATA
register, the byte count decrements by one.
To read USB OUT data, the 8051 first reads byte count registers OUTnBCL and OUTnBCH to
determine how many bytes to transfer out of the OUT FIFO. (The 8051 can also quickly test ISO
output endpoints for zero byte counts using the ZBCOUT register.) Then, the CPU reads that
number of bytes from the ISODATA register. Separate byte counts are maintained for each endpoint, so the CPU can read the FIFOs in a discontinuous manner. For example, if EP8 indicates a
byte count of 100, and EP9 indicates a byte count of 50, the CPU could read 50 bytes from EP8,
then read 10 bytes from EP9, and resume reading EP8. At this moment the byte count for EP8
would read 50.
There are no byte count registers for the IN endpoints. The USB core automatically tracks the
number of bytes loaded by the 8051.
If the 8051 does not load an IN isochronous endpoint FIFO during a 1-ms frame, and the host
requests data from that endpoint during the next frame (IN token), the USB Core responds according to the setting of the ISOSEND0 bit (USBPAIR.7). If ISOSEND0=1, the core returns a zerolength data packet in response to the host IN token. If ISOSEND=0, the core does not respond to
the IN token.
It is the responsibility of the 8051 programmer to ensure that the number of bytes written to the IN
FIFO does not exceed the maximum packet size as reported during enumeration.
12.5
CPU Registers
CPUCS
CPU Control and Status
7F92
b7
b6
b5
b4
b3
b2
b1
b0
RV3
RV2
RV1
RV0
0
0
CLK24OE
8051RES
R
R
R
R
R
R
R/W
R
RV3
RV2
RV1
RV0
0
0
1
1
Figure 12-5. CPU Control and Status Register
This register enables the CLK24 output and permits the host to reset the 8051 using a Firmware
Download.
Page 12-6
EZ-USB Technical Reference Manual v1.10
Bit 7-4:
RV[3..0]
Silicon Revision
These register bits define the silicon revision. Consult individual Cypress Semiconductor data
sheets for values.
Bit 1:
CLK24OE
Output enable - CLK24 pin
When this bit is set to 1, the internal 24-MHz clock is connected to the EZ-USB CLK24 pin.
When this bit is 0, the CLK24 pin drives HI. This bit can be written by the 8051 only.
Bit 0:
8051RES
8051 reset
The USB host writes “1” to this bit to reset the 8051, and “0” to run the 8051. Only the USB
host can write this bit.
12.6
Port Configuration
PORTACFG
IO Port A Configuration
7F93
b7
b6
b5
b4
b3
b2
b1
b0
RxD1OUT
RxD0OUT
FRD
FWR
CS
OE
T1OUT
T0OUT
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
PORTBCFG
IO Port B Configuration
7F94
b7
b6
b5
b4
b3
b2
b1
b0
T2OUT
INT6
INT5
INT4
TXD1
RXD1
T2EX
T2
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
PORTCCFG
IO Port C Configuration
7F95
b7
b6
b5
b4
b3
b2
b1
b0
RD
WR
T1
T0
INT1
INT0
TXD0
RXD0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Figure 12-6. IO Port Configuration Registers
Chapter 12. EZ-USB Registers
Page 12-7
EZ-USB Technical Reference Manual
These three registers control the three IO ports on the EZ-USB chip. They select between IO
ports and various alternate functions. They are read/write by the 8051.
When PORTnCFG=0, the port pin functions as IO, using the OUT, PINS, and OE control bits.
Data written to an OUTn registers appears on an IO Port pin if the corresponding output enable bit
(OEn) is HI.
When PORTnCFG=1, the pin assumes the alternate function shown in Table 12-4 on the following
page.
Table 12-4. IO Pin Alternate Functions
Page 12-8
I/O
Name
PA0
T0OUT
Timer 0 Output
Alternate Functions
PA1
T1OUT
Timer 1 Output
PA2
OE#
External Memory Output Enable
PA3
CS#
PA4
FWR#
Fast Access Write Strobe
External Memory Chip Select
PA5
FRD#
Fast Access Read Strobe
PA6
RXD0OUT
Mode 0: UART0 Synchronous Data Output
Mode 0: UART1 Synchronous Data Output
PA7
RXD1OUT
PB0
T2
PB1
T2EX
Timer/Counter 2 Capture/Reload Input
PB2
RxD1
Serial Port 1 Input
PB3
TxD1
Mode 0: Clock Output
Modes 1-3: Serial Port 1 Data Output
PB4
INT4
INT4 Interrupt Request
PB5
INT5#
INT5 Interrupt Request
Timer/Counter 2 Clock Input
PB6
INT6
PB7
T2OUT
INT6 Interrupt Request
PC0
RxD0
Serial Port 0 Input
PC1
TxD0
Mode 0: Clock Output
Modes 1-3: Serial Port 0 Data Output
PC2
INT0#
INT0 Interrupt Request
PC3
INT1#
INT1 Interrupt Request
PC4
T0
Timer/Counter 0 External Input
PC5
T1
Timer/Counter 1 External Input
PC6
WR#
External Memory Write Strobe
PC7
RD#
External Memory Read Strobe
Timer/Counter 2 Overflow Indication
EZ-USB Technical Reference Manual v1.10
12.7
Input-Output Port Registers
OUTA
Port A Outputs
7F96
b7
b6
b5
b4
b3
b2
b1
b0
OUTA7
OUTA6
OUTA5
OUTA4
OUTA3
OUTA2
OUTA1
OUTA0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
OUTB
Port B Outputs
7F97
b7
b6
b5
b4
b3
b2
b1
b0
OUTB7
OUTB6
OUTB5
OUTB4
OUTB3
OUTB2
OUTB1
OUTB0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
OUTC
Port C Outputs
7F98
b7
b6
b5
b4
b3
b2
b1
b0
OUTC7
OUTC6
OUTC5
OUTC4
OUTC3
OUTC2
OUTC1
OUTC0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Figure 12-7. Output Port Configuration Registers
The OUTn registers provide the data that drives the port pin when OE=1 and the PORTnCFG pin
is 0. If the port pin is selected a an input (OE=0), the value stored in the corresponding OUTn bit is
stored in an output latch but not used.
Chapter 12. EZ-USB Registers
Page 12-9
EZ-USB Technical Reference Manual
PINSA
Port A Pins
7F99
b7
b6
b5
b4
b3
b2
b1
b0
PINA7
PINA6
PINA5
PINA4
PINA3
PINA2
PINA1
PINA0
R
R
R
R
R
R
R
R
x
x
x
x
x
x
x
x
PINSB
Port B Pins
7F9A
b7
b6
b5
b4
b3
b2
b1
b0
PINB7
PINB6
PINB5
PINB4
PINB3
PINB2
PINB1
PINB0
R
R
R
R
R
R
R
R
x
x
x
x
x
x
x
x
PINSC
Port C Pins
7F9B
b7
b6
b5
b4
b3
b2
b1
b0
PINC7
PINC6
PINC5
PINC4
PINC3
PINC2
PINC1
PINC0
R
R
R
R
R
R
R
R
x
x
x
x
x
x
x
x
Figure 12-8. PINSn Registers
The PINSn registers contain the current value of the port pins, whether they are selected as IO
ports or alternate functions.
Page 12-10
EZ-USB Technical Reference Manual v1.10
OEA
Port A Output Enable
7F9C
b7
b6
b5
b4
b3
b2
b1
b0
OEA7
OEA6
OEA5
OEA4
OEA3
OEA2
OEA1
OEA0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
x
x
x
x
x
x
x
x
OEB
Port B Output Enable
7F9D
b7
b6
b5
b4
b3
b2
b1
b0
OEB7
OEB6
OEB5
OEB4
OEB3
OEB2
OEB1
OEB0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
x
x
x
x
x
x
x
x
OEC
Port C Output Enable
7F9E
b7
b6
b5
b4
b3
b2
b1
b0
OEC7
OEC6
OEC5
OEC4
OEC3
OEC2
OEC1
OEC0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
x
x
x
x
x
x
x
x
Figure 12-9. Output Enable Registers
The OE registers control the output enables on the tri-state drivers connected to the port pins.
When these bits are “1,” the port is an output, unless the corresponding PORTnCFG bit is set to a
“1.”
12.8
Isochronous Control/Status Registers
ISOERR
Isochronous OUT EP Error
7FA0
b7
b6
b5
b4
b3
b2
b1
b0
ISO15ERR
ISO14ERR
ISO13ERR
ISO12ERR
ISO11ERR
ISO10ERR
ISO9ERR
ISO8ERR
R
R
R
R
R
R
R
R
x
x
x
x
x
x
x
x
Figure 12-10. Isochronous OUT Endpoint Error Register
Chapter 12. EZ-USB Registers
Page 12-11
EZ-USB Technical Reference Manual
The ISOERR bits are updated at every SOF. They indicate that a CRC error was received on a
data packet for the current frame. The ISOERR bit status refers to the USB data received in the
previous frame, and which is currently in the endpoint’s OUT FIFO. If the ISOERR bit = 1, indicating a bad CRC check, the data is still available in the OUTnDATA register.
ISOCTL
Isochronous Control
7FA1
b7
b6
b5
b4
b3
b2
b1
b0
-
-
-
-
PPSTAT
MBZ
MBZ
ISODISAB
R
R
R
R
R
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Figure 12-11. Isochronous Control Register
Bit 3:
PPSTAT
Ping-Pong Status
This bit indicates the isochronous buffer currently in use by the EZ-USB core. It is used only
for diagnostic purposes.
Bits 2,1:
MBZ
Must be zero
These bits must always be written with zeros.
Bit 0:
ISODISAB
ISO Endpoints Disable
ISODISAB=0 enables all 16 isochronous endpoints
ISODISAB=1 disables all 16 isochronous endpoints, making the 2,048 bytes of isochronous
FIFO memory available as 8051 data memory at 0x2000-0x27FF.
ZBCOUT
Zero Byte Count Bits
7FA2
b7
b6
b5
b4
b3
b2
b1
b0
EP15
EP14
EP13
EP12
EP11
EP10
EP9
EP8
R
R
R
R
R
R
R
R
x
x
x
x
x
x
x
x
Figure 12-12. Zero Byte Count Register
Bits 0-7:
EP(n)
Zero Byte Count for ISO OUT Endpoints
The 8051 can check these bits as a fast way to check all of the OUT isochronous endpoints at
once for no data received during the previous frame. A “1” in any bit position means that a
zero byte Isochronous OUT packet was received for the indicated endpoint.
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12.9
I2C Registers
I2CS
7FA5
I2C Control and Status
b7
b6
b5
b4
b3
b2
b1
b0
START
STOP
LASTRD
ID1
ID0
BERR
ACK
DONE
R/W
R/W
R/W
R
R
R
R
R
0
0
0
x
x
0
0
0
I2DAT
7FA6
I2C Data
b7
b6
b5
b4
b3
b2
b1
b0
D7
D6
D5
D4
D3
D2
D1
D0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
x
x
x
x
x
x
x
x
Figure 12-13. I2C Transfer Registers
The 8051 uses these registers to transfer data over the EZ-USB I2C bus.
Bit 7:
START
Signal START condition
The 8051 sets the START bit to “1” to prepare an I2C bus transfer. If START=1, the next 8051
load to I2DAT will generate the start condition followed by the serialized byte of data in I2DAT.
The 8051 loads byte data into I2DAT after setting the START bit. The I2C controller clears the
START bit during the ACK interval.
Bit 6:
STOP
Signal STOP condition
The 8051 sets STOP=1 to terminate an I2C bus transfer. The I2C controller clears the STOP
bit after completing the STOP condition. If the 8051 sets the STOP bit during a byte transfer,
the STOP condition will be generated immediately following the ACK phase of the byte transfer. If no byte transfer is occurring when the STOP bit is set, the STOP condition will be carried
out immediately on the bus. Data should not be written to I2CS or I2DAT until the STOP bit
returns low.
Bit 5:
LASTRD
Last Data Read
To read data over the I2C bus, an I2C master floats the SDA line and issues clock pulses on
the SCL line. After every eight bits, the master drives SDA low for one clock to indicate ACK.
To signal the last byte of the read transfer, the master floats SDA at ACK time to instruct the
slave to stop sending. This is controlled by the 8051 by setting LastRD=1 before reading the
Chapter 12. EZ-USB Registers
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EZ-USB Technical Reference Manual
last byte of a read transfer. The I2C controller clears the LastRD bit at the end of the transfer
(at ACK time).
Note
Setting LastRD does not automatically generate a STOP condition. The 8051 should also set the
STOP bit at the end of a read transfer.
Bit 4-3:
ID1, ID0
Boot EEPROM ID
These bits are set by the boot loader to indicate whether an 8-bit address or 16-bit address
EEPROM at slave address 000 or 001 was detected at power-on. Normally, they are used for
debug purposes only.
Bit 2:
BERR
Bus Error
This bit indicates an I2C bus error. BERR=1 indicates that there was bus contention, which
results when an outside device drives the bus LO when it shouldn’t, or when another bus master wins arbitration, taking control of the bus. BERR is cleared when 8051 reads or writes the
IDATA register.
Bit 1:
ACK
Acknowledge bit
Every ninth SCL or a write transfer the slave indicates reception of the byte by asserting ACK.
The EZ-USB controller floats SDA during this time, samples the SDA line, and updates the
ACK bit with the complement of the detected value. ACK=1 indicates acknowledge, and
ACK=0 indicates not-acknowledge. The EZ-USB core updates the ACK bit at the same time it
sets DONE=1. The ACK bit should be ignored for read transfers on the bus.
Bit 0:
DONE
I2C Transfer DONE
The I2C controller sets this bit whenever it completes a byte transfer, right after the ACK stage.
The controller also generates an I2C interrupt request (8051 INT3) when it sets the DONE bit.
The I2C controller automatically clears the DONE bit and the I2C interrupt request bit whenever the 8051 reads or writes the I2DAT register.
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12.10 Interrupts
IVEC
Interrupt Vector
7FA8
b7
b6
b5
b4
b3
b2
b1
b0
0
IV4
IV3
IV2
IV1
IV0
0
0
R
R
R
R
R
R
R
R
0
0
0
0
0
0
0
0
Figure 12-14. Interrupt Vector Register
IVEC indicates the source of an interrupt from the USB Core. When the USB core generates an
INT2 (USB) interrupt request, it updates IVEC to indicate the source of the interrupt. The interrupt
sources are encoded on IV[4..0] as shown in Figure 9-2.
IN07IRQ
Endpoint 0-7 IN Interrupt Request
7FA9
b7
b6
b5
b4
b3
b2
b1
b0
IN7IR
IN6IR
IN5IR
IN4IR
IN3IR
IN2IR
IN1IR
IN0IR
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
OUT07IRQ
Endpoint 0-7 OUT Interrupt Requests
7FAA
b7
b6
b5
b4
b3
b2
b1
b0
OUT7IR
OUT6IR
OUT5IR
OUT4IR
OUT3IR
OUT2IR
OUT1IR
OUT0IR
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
x
x
x
x
x
x
x
x
Figure 12-15. IN/OUT Interrupt Request (IRQ) Registers
These interrupt request (IRQ) registers indicate the pending interrupts for each bulk endpoint. An
interrupt request (IR) bit becomes active when the BSY bit for an endpoint makes a transition from
one to zero (the endpoint becomes un-busy, giving access to the 8051). The IR bits function independently of the Interrupt Enable (IE) bits, so interrupt requests are held whether or not the interrupts are enabled.
The 8051 clears an interrupt request bit by writing a “1” to it (see the following Note).
Chapter 12. EZ-USB Registers
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EZ-USB Technical Reference Manual
Note
Do not clear an IRQ bit by reading an IRQ register, ORing its contents with a bit mask, and writing back the IRQ register. This will clear ALL pending interrupts. Instead, simply write the bit
mask value (with the IRQ you want to clear) directly to the IRQ register.
USBIRQ
USB Interrupt Request
7FAB
b7
b6
b5
b4
b3
b2
b1
b0
-
-
-
URESIR
SUSPIR
SUTOKIR
SOFIR
SUDAVIR
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Figure 12-16. USB Interrupt Request (IRQ) Registers
USBIRQ indicates the interrupt request status of the USB reset, suspend, setup token, start of
frame, and setup data available interrupts.
Bit 4:
URESIR
USB Reset Interrupt Request
The EZ-USB core sets this bit to “1” when it detects a USB bus reset.
Because this bit can change state while the 8051 is in reset, it may be active when the 8051
comes out of reset, although it is reset to “0” by a power-on reset. Write a “1” to this bit to clear
the interrupt request. See Chapter 10, "EZ-USB Resets" for more information about this bit.
Bit 3:
SUSPIR
USB Suspend Interrupt Request
The EZ-USB core sets this bit to “1” when it detects USB SUSPEND signaling (no bus activity
for 3 ms). Write a “1” to this bit to clear the interrupt request.
Because this bit can change state while the 8051 is in reset, it may be active when the 8051
comes out of reset, although it is reset to “0” by a power-on reset. See Chapter 11, "EZ-USB
Power Management" for more information about this bit.
Bit 2:
SUTOKIR
SETUP Token Interrupt Request
The EZ-USB core sets this bit to “1” when it receives a SETUP token. Write a “1” to this bit to
clear the interrupt request. See Chapter 7, "EZ-USB Endpoint Zero" for more information on
the handling of SETUP tokens.
Because this bit can change state while the 8051 is in reset, it may be active when the 8051
comes out of reset, although it is reset to “0” by a power-on reset.
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Bit 1:
SOFIR
Start of frame Interrupt Request
The EZ-USB core sets this bit to “1” when it receives a SOF packet. Write a “1” to this bit to
clear the interrupt condition.
Because this bit can change state while the 8051 is in reset, it may be active when the 8051
comes out of reset, although it is reset to “0” by a power-on reset.
Bit 0:
SUDAVIR
SETUP data available Interrupt Request
The EZ-USB core sets this bit to “1” when it has transferred the eight data bytes from an endpoint zero SETUP packet into internal registers (at SETUPDAT). Write a “1” to this bit to clear
the interrupt condition.
Because this bit can change state while the 8051 is in reset, it may be active when the 8051
comes out of reset, although it is reset to “0” by a power-on reset.
IN07EN
Endpoint 0-7 IN Interrupt Enables
7FAC
b7
b6
b5
b4
b3
b2
b1
b0
IN7IEN
IN6IEN
IN5IEN
IN4IEN
IN3IEN
IN2IEN
IN1IEN
IN0IEN
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
OUT07IEN
Endpoint 0-7 OUT Interrupt Enables
7FAD
b7
b6
b5
b4
b3
b2
b1
b0
OUT7IEN
OUT6IEN
OUT5IEN
OUT4IEN
OUT3IEN
OUT2IEN
OUT1IEN
OUT0IEN
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
x
x
x
x
x
x
x
x
Figure 12-17. IN/OUT Interrupt Enable Registers
The Endpoint Interrupt Enable registers define which endpoints have active interrupts. They do
not affect the endpoint action, only the generation of an interrupt in response to endpoint events.
When the IEN bit for an endpoint is “0,” the interrupt request bit for that endpoint is ignored, but
saved. When the IEN bit for an endpoint is “1,” any IRQ bit equal to “1” generates an 8051 INT2
request.
Chapter 12. EZ-USB Registers
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EZ-USB Technical Reference Manual
Note
The INT2 interrupt (EIE.0) and the 8051 global interrupt enable (EA) must be enabled for the
endpoint interrupts to propagate to the 8051. Once the INT2 interrupt is active, it must be cleared
by software.
USBIEN
USB Interrupt Enable
7FAE
b7
b6
b5
b4
b3
b2
b1
b0
-
-
-
URESIE
SUSPIE
SUTOKIE
SOFIE
SUDAVIE
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Figure 12-18. USB Interrupt Enable Register
USBIEN bits gate the interrupt request to the 8051 for USB reset, suspend, SETUP token, start of
frame, and SETUP data available.
Bit 4:
URESIE
USB Reset Interrupt Enable
This bit is the interrupt mask for the URESIR bit. When this bit is “1,” the interrupt is enabled,
when it is “0,” the interrupt is disabled.
Bit 3:
SUSPIE
USB Suspend Interrupt Enable
This bit is the interrupt mask for the SUSPIR bit. When this bit is “1,” the interrupt is enabled,
when it is “0,” the interrupt is disabled.
Bit 2:
SUTOKIE
SETUP Token Interrupt Enable
This bit is the interrupt mask for the SUTOKIR bit. When this bit is “1,” the interrupt is enabled,
when it is “0,” the interrupt is disabled.
Bit 1:
SOFIE
Start of frame Interrupt Enable
This bit is the interrupt mask for the SOFIE bit. When this bit is “1,” the interrupt is enabled,
when it is “0,” the interrupt is disabled.
Bit 0:
SUDAVIE
SETUP data available Interrupt Enable
This bit is the interrupt mask for the SUDAVIE bit. When this bit is “1,” the interrupt is enabled,
when it is “0,” the interrupt is disabled.
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USBBAV
Breakpoint and Autovector
7FAF
b7
b6
b5
b4
b3
b2
b1
b0
-
-
-
-
BREAK
BPPULSE
BPEN
AVEN
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Figure 12-19. Breakpoint and Autovector Register
Bit 3:
BREAK
Breakpoint enable
The BREAK bit is set when the 8051 address bus matches the address held in the bit breakpoint address registers (next page). The BKPT pin reflects the state of this bit. The 8051
writes a “1” to the BREAK bit to clear it. It is not necessary to clear the BREAK bit if the pulse
mode bit (BPPULSE) is set.
Bit 2:
BPPULSE
Breakpoint pulse mode
The 8051 sets this bit to “1” to pulse the BREAK bit (and BKPT pin) high for 8 CLK24 cycles
when the 8051 address bus matches the address held in the breakpoint address registers.
when this bit is set to “0,” the BREAK bit (and BKPT pin) remains high until it is cleared by the
8051.
Bit 1:
BPEN
Breakpoint enable
If this bit is “1,” a BREAK signal is generated whenever the 16-bit address lines match the
value in the Breakpoint Address Registers (BPADDRH/L). The behavior of the BREAK bit and
associated BKPT pin signal is either latched or pulsed, depending on the state of the
BPPULSE bit.
Bit 0:
AVEN
Auto-vector enable
If this bit is “1,” the EZ-USB Auto-vector feature is enabled. If it is 0, the auto-vector feature is
disabled. See Chapter 9, "EZ-USB Interrupts" for more information on the auto-vector feature.
IBNIRQ
IN Bulk NAK Interrupt Requests
7FB0
b7
b6
b5
b4
b3
b2
b1
b0
-
EP6IN
EP5IN
EP4IN
EP3IN
EP2IN
EP1IN
EP0IN
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
x
x
x
x
x
x
x
x
Figure 12-20. IN Bulk NAK Interrupt Request Register
Chapter 12. EZ-USB Registers
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EZ-USB Technical Reference Manual
These bits are set when a bulk IN endpoint (0-6) received an IN token while the endpoint was not
armed for data transfer. In this case the SIE automatically sends a NAK response, and sets the
corresponding IBNIRQ bit. If the IBN interrupt is enabled (USBIEN.5=1), and the endpoint interrupt is enabled in the IBNIEN register, an interrupt is request generated. The 8051 can test the
IBNIRQ register to determine which of the endpoints caused the interrupt. The 8051 clears an
IBNIRQ bit by writing a “1” to it.
IBNIEN
IN Bulk NAK Interrupt Enables
7FB1
b7
b6
b5
b4
b3
b2
b1
b0
-
EP6IN
EP5IN
EP4IN
EP3IN
EP2IN
EP1IN
EP0IN
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
x
x
0
0
0
0
0
0
Figure 12-21. IN Bulk NAK Interrupt Enable Register
Each of the individual IN endpoints may be enabled for an IBN interrupt using the IBNEN register.
The 8051 sets an interrupt enable bit to 1 to enable the corresponding interrupt.
BPADDRH
Breakpoint Address High
7FB2
b7
b6
b5
b4
b3
b2
b1
b0
A15
A14
A13
A12
A11
A10
A9
A8
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
BPADDRL
Breakpoint Address Low
7FB3
b7
b6
b5
b4
b3
b2
b1
b0
A7
A6
A5
A4
A3
A2
A1
A0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
x
x
x
x
x
x
x
x
Figure 12-22. IN/OUT Interrupt Enable Registers
When the current 16-bit address (code or xdata) matches the BPADDRH/BPADDRL address, a
breakpoint event occurs. The BPPULSE and BPEN bits in the USBBAV register control the action
taken on a breakpoint event.
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EZ-USB Technical Reference Manual v1.10
If the BPEN bit is “0,” address breakpoints are ignored. If BPEN is “1” and BPPULSE is “1,” an 8
CLK24 wide pulse appears on the BKPT pin. If BPEN is “1” and BPPULSE is “0,” the BKPT pin
remains active until the 8051 clears the BREAK bit by writing “1” to it.
12.11 Endpoint 0 Control and Status Registers
EP0CS
Endpoint Zero Control and Status
7FB4
b7
b6
b5
b4
b3
b2
b1
b0
-
-
-
-
OUTBSY
INBSY
HSNAK
EP0STALL
R
R
R
R
R
R
R/W
R/W
0
0
0
0
1
0
0
0
IN0BC
Endpoint Zero IN Byte Count
7FB5
b7
b6
b5
b4
b3
b2
b1
b0
-
BC6
BC5
BC4
BC3
BC2
BC1
BC0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
OUT0BC
Endpoint Zero OUT Byte Count
7FC5
b7
b6
b5
b4
b3
b2
b1
b0
-
BC6
BC5
BC4
BC3
BC2
BC1
BC0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
Figure 12-23. Port Configuration Registers
These registers control EZ-USB CONTROL endpoint zero. Because endpoint zero is a bi-directional endpoint, the IN and OUT functionality is controlled by a single control and status (CS) register, unlike endpoints 1-7, which have separate INCS and OUTCS registers.
Bit 3:
OUTBSY
OUT Endpoint Busy
OUTBSY is a read-only bit that is automatically cleared when a SETUP token arrives. The
8051 sets the OUTBSY bit by writing a byte count to EPOUTBC.
If the CONTROL transfer uses an OUT data phase, the 8051 must load a dummy byte count
into OUT0BC to arm the OUT endpoint buffer. Until it does, the EZ-USB core will NAK the
OUT tokens.
Chapter 12. EZ-USB Registers
Page 12-21
EZ-USB Technical Reference Manual
Bit 2:
INBSY
IN Endpoint Busy
INBSY is a read-only bit that is automatically cleared when a SETUP token arrives. The 8051
sets the INBSY bit by writing a byte count to IN0BC.
If the CONTROL transfer uses an IN data phase, the 8051 loads the requested data into the
IN0BUF buffer, and then loads the byte count into IN0BC to arm the data phase of the CONTROL transfer. Alternatively, the 8051 can arm the data transfer by loading an address into
the Setup Data Pointer registers SUDPTRH/L. Until armed, the EZ-USB core will NAK the IN
tokens.
Bit 1:
HSNAK
Handshake NAK
HSNAK (Handshake NAK) is a read/write bit that is automatically set when a SETUP token
arrives. The 8051 clears HSNAK by writing a “1” to the register bit.
While HSNAK=1, the EZ-USB core NAKs the handshake (status) phase of the CONTROL
transfer. When HSNAK=0, it ACKs the handshake phase. The 8051 can clear HSNAK at any
time during a CONTROL transfer.
Bit 0:
EP0STALL
Endpoint Zero Stall
EP0STALL is a read/write bit that is automatically cleared when a SETUP token arrives. The
8051 sets EP0STALL by writing a “1” to the register bit.
While EP0STALL=1, the EZ-USB core sends the STALL PID for any IN or OUT token. This
can occur in either the data or handshake phase of the CONTROL transfer.
Note
To indicate an endpoint stall on endpoint zero, set both EP0STALL and HSNAK bits. Setting the
EP0STALL bit alone causes endpoint zero to NAK forever because the host keeps the control
transfer pending.
12.12 Endpoint 1-7 Control and Status Registers
Endpoints 1-7 IN and OUT are used for bulk or interrupt data. Table 12-5 shows the addresses for
the control/status and byte count registers associated with these endpoints. The bi-directional
CONTROL endpoint zero registers are described in Section 12.11, "Endpoint 0 Control and Status
Registers."
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EZ-USB Technical Reference Manual v1.10
Table 12-5. Control and Status Register Addresses for Endpoints 0-7
Address
7FB4
Function
Control and Status - Endpoint IN0
Name
EP0CS
7FB5
7FB6
Byte Count - Endpoint IN0
Control and Status - Endpoint IN1
IN0BC
IN1CS
7FB7
7FB8
Byte Count - Endpoint IN1
Control and Status - Endpoint IN2
IN1BC
IN2CS
7FB9
7FBA
Byte Count - Endpoint IN2
Control and Status - Endpoint IN3
IN2BC
IN3CS
7FBB
7FBC
Byte Count - Endpoint IN3
Control and Status - Endpoint IN4
IN3BC
IN4CS
7FBD
7FBE
Byte Count - Endpoint IN4
Control and Status - Endpoint IN5
IN4BC
IN5CS
7FBF
7FC0
Byte Count - Endpoint IN5
Control and Status - Endpoint IN6
IN5BC
IN6CS
7FC1
7FC2
Byte Count - Endpoint IN6
Control and Status - Endpoint IN7
IN6BC
IN7CS
7FC3
7FC4
Byte Count - Endpoint IN7
Reserved
IN7BC
7FC5
7FC6
Byte Count - Endpoint OUT0
Control and Status - Endpoint OUT1
OUT0BC
OUT1CS
7FC7
7FC8
Byte Count - Endpoint OUT1
Control and Status - Endpoint OUT2
OUT1BC
OUT2CS
7FC9
7FCA
Byte Count - Endpoint OUT2
Control and Status - Endpoint OUT3
OUT2BC
OU37CS
7FCB
7FCC
Byte Count - Endpoint OUT3
Control and Status - Endpoint OUT4
OUT3BC
OUT4CS
7FCD
7FCE
Byte Count - Endpoint OUT4
Control and Status - Endpoint OUT5
OUT4BC
OUT5CS
7FCF
7FD0
Byte Count - Endpoint OUT5
Control and Status - Endpoint OUT6
OUT5BC
OUT6CS
7FD1
7FD2
Byte Count - Endpoint OUT6
Control and Status - Endpoint OUT7
OUT6BC
OUT7CS
7FD3
Byte Count - Endpoint OUT7
OUT7BC
Chapter 12. EZ-USB Registers
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EZ-USB Technical Reference Manual
INnCS
Endpoint (1-7) IN Control and Status
7FB6-7FC2*
b7
b6
b5
b4
b3
b2
b1
b0
-
-
-
-
-
-
INnBSY
INnSTL
R
R
R
R
R
R
R/W
R/W
0
0
0
0
0
0
0
0
* See Table 12-5 for individual control/status register addresses.
Figure 12-24. IN Control and Status Registers
Bit 1:
INnBSY
IN Endpoint (1-7) Busy
The BSY bit indicates the status of the endpoint’s IN Buffer INnBUF. The EZ-USB core sets
BSY=0 when the endpoint’s IN buffer is empty and ready for loading by the 8051. The 8051
sets BSY=1 by loading the endpoint’s byte count register.
When BSY=1, the 8051 should not write data to an IN endpoint buffer, because the endpoint
FIFO could be in the act of transferring data to the host over the USB. BSY=0 when the USB
IN transfer is complete and endpoint RAM data is available for 8051 access. USB IN tokens
for the endpoint are NAKd while BSY=0 (the 8051 is still loading data into the endpoint buffer).
A 1-to-0 transition of BSY (indicating that the 8051 can access the buffer) generates an interrupt request for the IN endpoint. After the 8051 writes the data to be transferred to the IN endpoint buffer, it loads the endpoint’s byte count register with the number of bytes to transfer,
which automatically sets BSY=1. This enables the IN transfer of data to the host in response
to the next IN token. Again, the CPU should never load endpoint data while BSY=1.
The 8051 writes a “1” to an IN endpoint busy bit to disarm a previously armed endpoint. (This
sets BSY=0.) The 8051 program should do this only after a USB bus reset, or when the host
selects a new interface or alternate setting that uses the endpoint. This prevents stale data
from a previous setting from being accepted by the host’s first IN transfer that uses the new
setting.
Note:
Even though the register description shows bit 1 as “R/W,” the 8051 can only clear this bit by writing a “1” to it. The 8051 can not directly set this bit.
To disarm a paired IN endpoint, write a “1” to the busy bit for both endpoints in the pair.
Bit 0:
INnSTL
IN Endpoint (1-7) Stall
The 8051 sets this bit to “1” to stall an endpoint, and to “0” to clear a stall.
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EZ-USB Technical Reference Manual v1.10
When the stall bit is “1,” the EZ-USB core returns a STALL Handshake for all requests to the
endpoint. This notifies the host that something unexpected has happened.
The 8051 sets an endpoint’s stall bit under two circumstances:
1. The host sends a “Set_Feature—Endpoint Stall” request to the specific endpoint.
2. The 8051 encounters any show stopper error on the endpoint, and sets the stall bit to tell
the host to halt traffic to the endpoint.
The 8051 clears an endpoint’s stall bit under two circumstances:
1. The host sends a “Clear_Feature--Endpoint Stall” request to the specific endpoint.
2. The 8051 receives some other indication from the host that the stall should be cleared
(this is referred to as “host intervention” in the USB Specification). This indication could be
a USB bus reset.
All stall bits are automatically cleared when the EZ-USB chip ReNumerates by pulsing the
DISCON bit HI.
INnBC
Endpoint (1-7) IN Byte Count
7FB7-7FC3*
b7
b6
b5
b4
b3
b2
b1
b0
-
D6
D5
D4
D3
D2
D1
D0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
x
x
x
x
x
x
x
x
* See Table 12-5 for individual byte count register addresses.
Figure 12-25. IN Byte Count Registers
The 8051 writes this register with the number of bytes it loaded into the IN endpoint buffer INnBUF.
Writing this register also arms the endpoint by setting the endpoint BSY bit to 1.
Legal values for these registers are 0-64. A zero transfer size is used to terminate a transfer that is
an integral multiple of MaxPacketSize. For example, a 256-byte transfer with maxPacketSize =
64, would require four packets of 64 bytes each plus one packet of 0 bytes.
The IN byte count should never be written while the endpoint’s BUSY bit is set.
When the register pairing feature is used (Chapter 6, "EZ-USB Bulk Transfers") IN2BC is used for
the EP2/EP3 pair, IN4BC is used for the EP4/EP5 pair, and IN6BC is used for the EP6/EP7 pair. In
the paired (double-buffered) mode, after the first write to the even-numbered byte count register,
the endpoint BSY bit remains at 0, indicating that only one of the buffers is full, and the other is still
empty. The odd numbered byte count register is not used when endpoints are paired.
Chapter 12. EZ-USB Registers
Page 12-25
EZ-USB Technical Reference Manual
OUTnCS
Endpoint (1-7) OUT Control and Status
7FC6-7FD2*
b7
b6
b5
b4
b3
b2
b1
b0
-
-
-
-
-
-
OUTnBSY
OUTnSTL
R
R
R
R
R
R
R
R/W
0
0
0
0
0
0
0
0
* See Table 12-5 for individual control/status register addresses.
Figure 12-26. OUT Control and Status Registers
Bit 1:
OUTnBSY
OUT Endpoint (1-7) Busy
The BSY bit indicates the status of the endpoint’s OUT Buffer OUTnBUF. The EZ-USB core
sets BSY=0 when the host data is available in the OUT buffer. The 8051 sets BSY=1 by loading the endpoint’s byte count register.
When BSY=1, endpoint RAM data is invalid--the endpoint buffer has been emptied by the
8051 and is waiting for new OUT data from the host, or it is the process of being loaded over
the USB. BSY=0 when the USB OUT transfer is complete and endpoint RAM data in OUTnBUF is available for the 8051 to read. USB OUT tokens for the endpoint are NAKd while
BSY=1 (the 8051 is still reading data from the OUT endpoint).
A 1-to-0 transition of BSY (indicating that the 8051 can access the buffer) generates an interrupt request for the OUT endpoint. After the 8051 reads the data from the OUT endpoint
buffer, it loads the endpoint’s byte count register with any value to re-arm the endpoint, which
automatically sets BSY=1. This enables the OUT transfer of data from the host in response to
the next OUT token. The CPU should never read endpoint data while BSY=1.
Bit 0:
OUTnSTL
OUT Endpoint (1-7) Stall
The 8051 sets this bit to “1” to stall an endpoint, and to “0” to clear a stall.
When the stall bit is “1,” the EZ-USB core returns a STALL Handshake for all requests to the
endpoint. This notifies the host that something unexpected has happened.
The 8051 sets an endpoint’s stall bit under two circumstances:
1.
The host sends a “Set_Feature—Endpoint Stall” request to the specific endpoint.
2.
The 8051 encounters any show stopper error on the endpoint, and sets the stall bit to tell
the host to halt traffic to the endpoint.
The 8051 clears an endpoint’s stall bit under two circumstances:
1. The host sends a “Clear_Feature—Endpoint Stall” request to the specific endpoint.
2. The 8051 receives some other indication from the host that the stall should be cleared
(this is referred to as “host intervention” in the USB Specification).
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EZ-USB Technical Reference Manual v1.10
All stall bits are automatically cleared when the EZ-USB chip ReNumerates.
OUTnBC
Endpoint (1-7) OUT Byte Count
7FC7-7FD3*
b7
b6
b5
b4
b3
b2
b1
b0
-
D6
D5
D4
D3
D2
D1
D0
R
R
R
R
R
R
R
R/W
0
0
0
0
0
0
0
0
* See Table 12-5 for individual control/status register addresses.
Figure 12-27. OUT Byte Count Registers
The 8051 reads this register to determine the number of bytes sent to an OUT endpoint. Legal
sizes are 0 - 64 bytes.
Each EZ-USB bulk OUT endpoint has a byte count register, which serves two purposes. The 8051
reads the byte count register to determine how many bytes were received during the last OUT
transfer from the host. The 8051 writes the byte count register (with any value) to tell the EZ-USB
core that it has finished reading bytes from the buffer, making the buffer available to accept the
next OUT transfer. Writing the byte count register sets the endpoint’s BSY bit to “1.”
When the register-pairing feature is used, OUT2BC is used for the EP2/EP3 pair, OUT4BC is used
for the EP4/EP5 pair, and OUT6BC is used for the EP6/EP7 pair. The odd-numbered byte count
registers should not be used. When the 8051 writes a byte to the even numbered byte count register, the EZ-USB core switches buffers. If the other buffer already contains data to be read by the
8051, the OUTnBSY bit remains at “0.”
All OUT tokens are NAKd until the 8051 is released from RESET, whereupon the ACK/NAK behavior is based on pairing.
Chapter 12. EZ-USB Registers
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EZ-USB Technical Reference Manual
12.13 Global USB Registers
SUDPTRH
Setup Data Pointer High
7FD4
b7
b6
b5
b4
b3
b2
b1
b0
A15
A14
A13
A12
A11
A10
A9
A8
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
x
x
x
x
x
x
x
x
SUDPTRL
Setup Data Pointer Low
7FD5
b7
b6
b5
b4
b3
b2
b1
b0
A7
A6
A5
A4
A3
A2
A1
A0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
x
x
x
x
x
x
x
x
Figure 12-28. Setup Data Pointer High/Low Registers
When the EZ-USB chip receives a “Get_Descriptor” request on endpoint zero, it can instruct the
EZ-USB core to handle the multi-packet IN transfer by loading these registers with the address of
an internal table containing the descriptor data. The descriptor data tables may be placed in internal program/data RAM or in unused Endpoint 0-7 RAM. The SUDPTR does not operate with
external memory. The SUDPTR registers should be loaded in HIGH/LOW order.
In addition to loading SUDPTRL, the 8051 must also clear the HSNAK bit in the EP0CS register
(by writing a “1” to it) to complete the CONTROL transfer.
Note
Any host request that uses the EZ-USB Setup Data Pointer to transfer IN data must indicate the
number of bytes to transfer in bytes 6 (wLenghthL) and 7 (wLengthH) of the SETUP packet.
These bytes are pre-assigned in the USB Specification to be length bytes in all standard device
requests such as “Get_Descriptor.” If vendor-specific requests are used to transfer large blocks
of data using the Setup Data Pointer, they must include this pre-defined length field in bytes 6-7
to tell the EZ-USB core how many bytes to transfer using the Setup Data Pointer.
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EZ-USB Technical Reference Manual v1.10
USBCS
USB Control and Status
7FD6
b7
b6
b5
b4
b3
b2
b1
b0
WAKESRC
-
-
-
DISCON
DISCOE
RENUM
SIGRSUME
R/W
R
R
R
R/W
R/W
R/W
R/W
0
0
0
0
0
1
0
0
Figure 12-29. USB Control and Status Registers
Bit 7:
WAKESRC
Wakeup source
This bit indicates that a high to low transaction was detected on the WAKEUP# pin. Writing a
“1” to this bit resets it to “0.”
Bit 3:
DISCON
Signal a Disconnect on the DISCON# pin
The EZ-USB DISCON# pin reflects the complement of this bit. This bit is normally set to 0 so
that the action of the DISCOE bit (below) either floats the DISCON# pin or drives it HI.
Bit 2:
DISCOE
Disconnect Output Enable
DISCOE controls the output buffer on the DISCON# pin. When DISCOE=0, the pin floats, and
when DISCOE=1, it drives to the complement of the DISCON bit (above).
DISCOE is used in conjunction with the RENUM bit to perform ReNumeration (Chapter 5,
"EZ-USB Enumeration and ReNumeration™."
Bit 1:
RENUM
ReNumerate
This bit controls which entity, the USB core or the 8051, handles USB device requests. When
RENUM=0, the EZ-USB core handles all device requests. When RENUM=1, the 8051 handles all device requests except Set_Address.
The 8051 sets RENUM=1 during a bus disconnect to transfer USB control to the 8051. The
EZ-USB core automatically sets RENUM=1 under two conditions:
1. Completion of a “B2” boot load (Chapter 5, "EZ-USB Enumeration and ReNumeration™").
2. When external memory is used (EA=1) and no boot I2C EEPROM is used (see
Section 10.3.3, "External ROM").
Bit 0:
SIGRSUME
Signal remote device resume
The 8051 sets SIGRSUME=1 to drive the “K” state onto the USB bus. This should be done
only by a device that is capable of remote wakeup, and then only during the SUSPEND state.
To signal RESUME, the 8051 sets SIGRSUME=1, waits 10-15 ms, then sets SIGRSUME=0.
Chapter 12. EZ-USB Registers
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EZ-USB Technical Reference Manual
TOGCTL
Data Toggle Control
7FD7
b7
b6
b5
b4
b3
b2
b1
b0
Q
S
R
IO
0
EP2
EP1
EP0
R
R/W
R/W
R/W
R/W
R/W
R/W
R/W
x
x
x
x
x
x
x
x
Figure 12-30. Data Toggle Control Register
Bit 7:
Q
Data Toggle Value
Q=0 indicates DATA0 and Q=1 indicates DATA1, for the endpoint selected by the IO and
EP[2..0] bits. The 8051 writes the endpoint select bits (IO and EP[2..0]), before reading this
value.
Bit 6:
S
Set Data Toggle to DATA1
After selecting the desired endpoint by writing the endpoint select bits (IO and EP[2..0]) the
8051 sets S=1 to set the data toggle to DATA1. The endpoint selection bits should not be
changed while this bit is written.
Note
At this writing there is no known reason to set an endpoint data toggle to 1. This bit is provided
for generality and testing only.
Bit 5:
R
Set Data Toggle to DATA0
After selecting the desired endpoint by writing the endpoint select bits (IO and EP[2..0]) the
8051 sets R=1 to set the data toggle to DATA0. The endpoint selection bits should not be
changed while this bit is written. For advice on when to reset the data toggle, see Chapter 7,
"EZ-USB Endpoint Zero."
Bit 4:
IO
Select IN or OUT endpoint
The 8051 sets this bit to select an endpoint direction prior to setting its R or S bit. IO=0 selects
an OUT endpoint, IO=1 selects an IN endpoint.
Bit 2-0:
EP
Select endpoint
The 8051 sets these bits to select an endpoint prior to setting its R or S bit. Valid values are 07 to correspond to bulk endpoints IN0-IN7 and OUT0-OUT7.
Page 12-30
EZ-USB Technical Reference Manual v1.10
USBFRAMEL
USB Frame Count Low
7FD8
b7
b6
b5
b4
b3
b2
b1
b0
FC7
FC6
FC5
FC4
FC3
FC2
FC1
FC0
R
R
R
R
R
R
R
R
x
x
x
x
x
x
x
x
USBFRAMEH
USB Frame Count High
7FD9
b7
b6
b5
b4
b3
b2
b1
b0
0
0
0
0
0
FC10
FC9
FC8
R
R
R
R
R
R
R
R
x
x
x
x
x
x
x
x
Figure 12-31. USB Frame Count High/Low Registers
Every millisecond the host sends a SOF token indicating “Start Of Frame,” along with an 11-bit
incrementing frame count. The EZ-USB copies the frame count into these registers at every SOF.
One use of the frame count is to respond to the USB SYNC_FRAME request (Chapter 7, "EZ-USB
Endpoint Zero").
If the USB core detects a missing or garbled SOF, it generates an internal SOF and increments
USBFRAMEL-USBRAMEH.
FNADDR
Function Address
7FDB
b7
b6
b5
b4
b3
b2
b1
b0
0
FA6
FA5
FA4
FA3
FA2
FA1
FA0
R
R
R
R
R
R
R
R
x
x
x
x
x
x
x
x
Figure 12-32. Function Address Register
During the USB enumeration process, the host sends a device a unique 7-bit address, which the
EZ-USB core copies into this register. There is normally no reason for the CPU to know its USB
device address because the USB Core automatically responds only to its assigned address.
Note
During ReNumeration the USB Core sets register to 0 to allow the EZ-USB chip to respond to
the default address 0.
Chapter 12. EZ-USB Registers
Page 12-31
EZ-USB Technical Reference Manual
USBPAIR
USB Endpoint Pairing
7FDD
b7
b6
b5
b4
b3
b2
b1
b0
ISOSEND0
-
PR6OUT
PR4OUT
PR2OUT
PR6IN
PR4IN
PR2IN
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
x
0
0
0
0
0
0
Figure 12-33. USB Endpoint Pairing Register
Bit 7:
ISOSEND0
Isochronous Send Zero Length Data Packet
The ISOSEND0 bit is used when the EZ-USB chip receives an isochronous IN token while the
IN FIFO is empty. If ISOSEND0=0 (the default value), the EZ-USB core does not respond to
the IN token. If ISOSEND0=1, the EZ-USB core sends a zero-length data packet in response
to the IN token. Which action to take depends on the overall system design. The ISOSEND0
bit applies to all of the isochronous IN endpoints, IN8BUF through IN15BUF.
Bit 5-3:
PRnOUT
Pair Bulk OUT Endpoints
Set the endpoint pairing bits (PRxOUT) to “1” to enable double-buffering of the bulk OUT endpoint buffers. With double buffering enabled, the 8051 can operate on one buffer while
another is being transferred over USB. The endpoint busy and interrupt request bits function
identically, so the 8051 code requires no code modification to support double buffering.
When an endpoint is paired, the 8051 uses only the even-numbered endpoint of the pair. The
8051 should not use the paired odd endpoint’s IRQ, IEN, VALID bits or the buffer associated
with the odd numbered endpoint.
Bit 2-0:
PRnIN
Pair Bulk IN Endpoints
Set the endpoint pairing bits (PRxIN) to “1” to enable double-buffering of the bulk IN endpoint
buffers. With double buffering enabled, the 8051 can operate on one buffer while another is
being transferred over USB.
When an endpoint is paired, the 8051 should access only the even-numbered endpoint of the
pair. The 8051 should not use the IRQ, IEN, VALID bits or the buffer associated with the odd
numbered endpoint.
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EZ-USB Technical Reference Manual v1.10
IN07VAL
Endpoints 0-7 IN Valid Bits
7FDE
b7
b6
b5
b4
b3
b2
b1
b0
IN7VAL
IN6VAL
IN5VAL
IN4VAL
IN3VAL
IN2VAL
IN1VAL
IN0VAL
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
1
0
1
0
1
1
1
OUT07VAL
Endpoints 0-7 OUT Valid Bits
7FDF
b7
b6
b5
b4
b3
b2
b1
b0
OUT7VAL
OUT6VAL
OUT5VAL
OUT4VAL
OUT3VAL
OUT2VAL
OUT1VAL
OUT0VAL
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
1
0
1
0
1
0
1
Figure 12-34. IN/OUT Valid Bits Register
The 8051 sets VAL=1 for any active endpoints, and VAL=0 for inactive endpoints. These bits
instruct the EZ-USB core to return a “no response” if an invalid endpoint is addressed, instead of a
NAK.
The default values of these registers are set to support all endpoints that exist in the default USB
device (see Table 5-1).
INISOVAL
Isochronous IN Endpoint Valid Bits
7FE0
b7
b6
b5
b4
b3
b2
b1
b0
IN15VAL
IN14VAL
IN13VAL
IN12VAL
IN11VAL
IN10VAL
IN9VAL
IN8VAL
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
1
1
1
OUTISOVAL
b7
Isochronous OUT Endpoint Valid Bits
b6
b5
b4
b3
b2
OUT15VAL OUT14VAL OUT13VAL OUT12VAL OUT11VAL OUT10VAL
7FE1
b1
b0
OUT9VAL
OUT8VAL
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
1
1
1
Figure 12-35. Isochronous IN/OUT Endpoint Valid Bits Register
Chapter 12. EZ-USB Registers
Page 12-33
EZ-USB Technical Reference Manual
The 8051 sets VAL=1 for active endpoints, and VAL=0 for inactive endpoints. These bits instruct
the EZ-USB core to return a “no response” if an invalid endpoint is addressed.
The default values of these registers are set to support all endpoints that exist in the default USB
device (see Table 5-1).
12.14 Fast Transfers
FASTXFR
Fast Transfer Control
7FE2
b7
b6
b5
b4
b3
b2
b1
b0
FISO
FBLK
RPOL
RMOD1
RMOD0
WPOL
WMOD1
WMOD0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
x
x
x
x
x
x
x
x
Figure 12-36. Fast Transfer Control Register
The EZ-USB core provides a fast transfer mode that improves the8051 transfer speed between
external logic and the isochronous and bulk endpoint buffers. The FASTXFR register enables the
modes for bulk and/or isochronous transfers, and selects the timing waveforms for the FRD# and
FWR# signals.
Bit 7:
FISO
Enable Fast ISO Transfers
The 8051 sets FISO=1 to enable fast isochronous transfers for all16 isochronous endpoint
FIFOs. When FISO=0, fast transfers are disabled for all 16 isochronous endpoints.
Bit 6:
FBLK
Enable Fast BULK Transfers
The 8051 sets FBLK=1 to enable fast bulk transfers using the Autopointer (see Section 12.15,
"SETUP Data") with BULK endpoints. When FBLK=0 fast transfers are disabled for BULK
endpoints.
Bit 5:
RPOL
FRD# Pulse Polarity
The 8051 sets RPOL=0 for active-low FRD# pulses, and RPOL=1 for active high FRD#
pulses.
Bit 4-3:
RMOD
FRD# Pulse Mode
These bits select the phasing and width of the FRD# pulse. See Figure 8-12.
Page 12-34
EZ-USB Technical Reference Manual v1.10
Bit 2:
WPOL
FWR# Pulse Polarity
The 8051 sets WPOL=0 for active-low FWR# pulses, and WPOL=1 for active high FWR#
pulses.
Bit 1-0:
WMOD
FWR# Pulse Mode
These bits select the phasing and width of the FWR# pulse. See Figure 8-11.
AUTOPTRH
Auto Pointer Address High
7FE3
b7
b6
b5
b4
b3
b2
b1
b0
A15
A14
A13
A12
A11
A10
A9
A8
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
x
x
x
x
x
x
x
x
AUTOPTRL
Auto Pointer Address Low
7FE4
b7
b6
b5
b4
b3
b2
b1
b0
A7
A6
A5
A4
A3
A2
A1
A0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
x
x
x
x
x
x
x
x
AUTODATA
Auto Pointer Data
7FE5
b7
b6
b5
b4
b3
b2
b1
b0
D7
D6
D5
D4
D3
D2
D1
D0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
x
x
x
x
x
x
x
x
Figure 12-37. Auto Pointer Registers
These registers implement the EZ-USB Autopointer.
AUTOPTRH/L
The 8051 loads a 16-bit address into the AUTOPTRH/L registers. Subsequent reads or writes to
the AUTODATA register increment the 16-bit value in these registers. The loaded address must
be in internal EZ-USB RAM. The 8051 can read these registers to determine the address must be
in internal EZ-USB RAM. The 8051 can read these registers to determine the address of the next
byte to be accessed via the AUTODATA register.
Chapter 12. EZ-USB Registers
Page 12-35
EZ-USB Technical Reference Manual
AUTODATA
8051 data read or written to the AUTODATA register accesses the memory addressed by the
AUTOPTRH/L registers, and increments the address after the read or write.
These registers allow FIFO access to the bulk endpoint buffers, as well as being useful for internal
data movement. Chapter 6, "EZ-USB Bulk Transfers" and Chapter 8, "EZ-USB Isochronous
Transfers" explain how to use the Autopointer for fast transfers to and from the EZ-USB endpoint
buffers.
12.15 SETUP Data
SETUPBUF
SETUP Data Buffer (8 Bytes)
7FE8-7FEF
b7
b6
b5
b4
b3
b2
b1
b0
D7
D6
D5
D4
D3
D2
D1
D0
R
R
R
R
R
R
R
R
x
x
x
x
x
x
x
x
Figure 12-38. SETUP Data Buffer
This buffer contains the 8 bytes of SETUP packet data from the most recently received CONTROL
transfer.
The data in SETUPBUF is valid when the SUDAVIR (Setup Data Available Interrupt Request) bit is
set. The 8051 responds to the SUDAV interrupt by reading the SETUP bytes from this buffer.
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EZ-USB Technical Reference Manual v1.10
12.16 Isochronous FIFO Sizes
OUTnADDR
ISO OUT Endpoint Start Address
7FF0-7FF7*
b7
b6
b5
b4
b3
b2
b1
b0
A9
A8
A7
A6
A5
A4
0
0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
x
x
x
x
x
x
x
x
INnADDR
ISO IN Endpoint Start Address
7FF8-7FFF*
b7
b6
b5
b4
b3
b2
b1
b0
A9
A8
A7
A6
A5
A4
0
0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
x
x
x
x
x
x
x
x
* See Table 12-6 for individual start address register addresses.
Figure 12-39. SETUP Data Buffer
Table 12-6. Isochronous FIFO Start Address Registers
Chapter 12. EZ-USB Registers
Address
Endpoint Start Address
7FF0
Endpoint 8 OUT Start Address
7FF1
Endpoint 9 OUT Start Address
7FF2
Endpoint 10 OUT Start Address
7FF3
Endpoint 11 OUT Start Address
7FF4
Endpoint 12 OUT Start Address
7FF5
Endpoint 13 OUT Start Address
7FF6
Endpoint 14 OUT Start Address
7FF7
Endpoint 15 OUT Start Address
7FF8
Endpoint 8 IN Start Address
7FF9
Endpoint 9 IN Start Address
7FFA
Endpoint 10 IN Start Address
7FFB
Endpoint 11 IN Start Address
7FFC
Endpoint 12 IN Start Address
7FFD
Endpoint 13 IN Start Address
7FFE
Endpoint 14 IN Start Address
7FFF
Endpoint 15 IN Start Address
Page 12-37
EZ-USB Technical Reference Manual
EZ-USB Isochronous endpoints use a pool of 1,024 double-buffered FIFO bytes. The 1,024 FIFO
bytes can be divided between any or all of the isochronous endpoints. The 8051 sets isochronous
endpoint FIFO sizes by writing starting addresses to these registers, starting with address 0.
Address bits A3-A0 are internally set to zero, so the minimum FIFO size is 16 bytes.
See Section 8.8, "Fast Transfer Speed" for details about how to set these registers.
Page 12-38
EZ-USB Technical Reference Manual v1.10
Chapter 13 EZ-USB AC/DC Parameters
13.1
Electrical Characteristics
13.1.1 Absolute Maximum Ratings
Storage Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -65oC to +150oC
Ambient Temperature Under Bias . . . . . . . . . . . . . . . . . . . . . . . . . -40oC to +85oC
Supply Voltage to Ground Potential . . . . . . . . . . . . . . . . . . . . . . . . . -0.5V to +4.0V
DC Input Voltage to Any Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.5V to +5.8V
13.1.2 Operating Conditions
Ta (Ambient Temperature Under Bias) . . . . . . . . . . . . . . . . . . . . . . . 0oC to +70oC
Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .+3.0V to +3.6V
Ground Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0V
Fosc (Oscillator or Crystal Frequency) . . . . . . . . . . . . . . . . . . . . 12 MHz +/- 0.25%
13.1.3 DC Characteristics
Table 13-1. DC Characteristics
Symbol
Parameter
VCC
Supply Voltage
Condition
Min Typ Max Unit
3.0
3.6
V
Notes
VIH
Input High Voltage
2.0
5.25
V
VIL
Input Low Voltage
-0.5
0.8
V
II
Input Leakage Current
0 < VIN < VCC
+ 10
µA Current is higher (-70µA typical)
in the switching range between
VIL-MAX and VIH-MIN
VOH
Output High Voltage
IOUT = 1.6 mA
VOL
Output Low Voltage
IOUT = -1.6 mA
CIN
Input Pin Capacitance
ISUSP
Suspend Current
ICC
Supply Current
2.4
V
0.4
V
10
pF
50
mA
µA
110
8051 running,
connected to USB
Chapter 13. EZ-USB AC/DC Parameters
Page 13-1
EZ-USB Technical Reference Manual
13.1.4 AC Electrical Characteristics
Specified Conditions: Capacitive load on all pins = 30 pF
13.1.5 General Memory Timing
Table 13-2. General Memory Timing
Symbol
Parameter
Min
tCL
1/CLK24 Frequency
tAV
Delay from Clock to Valid Address
Typ
Max
41.66
0
Unit
Notes
ns
10
ns
tCD
Delay from CLK24 to CS#
2
15
ns
tOED
Delay from CLK24 to OE#
2
15
ns
tWD
Delay from CLK24 to WR#
2
15
ns
tRD
Delay from CLK24 to RD#
2
15
ns
tPD
Delay from CLK24 to PSEN#
2
15
ns
13.1.6 Program Memory Read
Table 13-3. Program Memory Read
Symbol
Parameter
Formula
Min
3tCL-tAV-TDSU1
103
ns
tCL+1
42
ns
Data setup to CLK24
12
ns
Data Hold from CLK24
0
ns
tAA1
Address Access Time
tAH1
Address Hold from CLK24
tDSU1
tDH1
Max
Unit
Notes
13.1.7 Data Memory Read
Table 13-4. Data Memory Read
Symbol
Parameter
Formula
Min
3tCL-tAV-TDSU1
103
ns
tCL+1
42
ns
Data setup to CLK24
12
ns
Data Hold from CLK24
0
ns
tAA2
Address Access Time
tAH2
Address Hold from CLK24
tDSU2
tDH2
Page 13-2
Max
Unit
Notes
EZ-USB Technical Reference Manual v1.10
13.1.8 Data Memory Write
Table 13-5. Data Memory Write
Symbol
Parameter
tAH3
Address Hold from CLK24
tDV
CLK24 to Data Valid
tDVZ
Formula
Min
tCL+2
43
Max
tCL+16
Notes
ns
15
CLK24 to High Impedance
Unit
57
ns
ns
13.1.9 Fast Data Write
Table 13-6. Fast Data Write
Symbol
Parameter
Conditions
Min
Max
Unit
tCDO
Clock to Data Output Delay
3
15
ns
tCWO
Clock to FIFO Write Output
Delay
2
10
ns
tPFWD Propagation Delay Difference
from FIFO Write to DATA Out
1
Notes
ns
13.1.10 Fast Data Read
Table 13-7. Fast Data Read
Symbol
Min
Max
Unit
tCRO
Clock to FIFO Read Output
Delay
2
10
ns
tDSU4
Data Setup to Rising CLK24
12
ns
Data Hold from Rising
CLK24
2
ns
tDH4
Parameter
Chapter 13. EZ-USB AC/DC Parameters
Conditions
Notes
Page 13-3
EZ-USB Technical Reference Manual
tCL
CLK24
tAV
A [15.0]
tCD
tCD
tOED
tOED
tWD
tWD
tRD
tRD
tPD
tPD
CS#
OE#
WR#
RD#
PSEN#
Figure 13-1. External Memory Timing
tCL
CLK24
PSEN#
CS#
OE#
A [15.0]
tAV
tAA1
tAH1
tDSU1
tDH1
D [7.0]
Figure 13-2. Program Memory Read Timing
Page 13-4
EZ-USB Technical Reference Manual v1.10
tCL
CLK24
RD#
CS#
OE#
A [15.0]
tAA2
tAH2
tDSU2
tDH2
D [7.0]
Figure 13-3. Data Memory Read Timing
tCL
CLK24
CS#
WR#
tAH3
A [15.0]
tDV
tDVZ
D [7.0]
Figure 13-4. Data Memory Write Timing
Chapter 13. EZ-USB AC/DC Parameters
Page 13-5
EZ-USB Technical Reference Manual
EZ-USB
Fast Transfer Block Diagram
EZ-USB
AN2131Q
80
PQFP
ASIC
CLK24
FIFO Clock
D [7:0]
D [7:0]
FWR#
FIFO Write Stobe
FRD#
FIFO Read Stobe
Figure 13-5. Fast Transfer Mode Block Diagram
Page 13-6
EZ-USB Technical Reference Manual v1.10
tCL
CLK24
tDSU4
tDH4
Input
D[7..0]
tCRO
tCRO
FRD#[00]
Figure 13-6. Fast Transfer Read Timing [Mode 00]
tCL
CLK24
tCDO
tCDO
D[7..0]
Output
tCWO
tCWO
FWR#[00]
Figure 13-7. Fast Transfer Write Timing [Mode 00]
Chapter 13. EZ-USB AC/DC Parameters
Page 13-7
EZ-USB Technical Reference Manual
tCL
CLK24
tDH4
tDSU4
Input
D[7..0]
tCRO
tCRO
FRD#[01]
Figure 13-8. Fast Transfer Read Timing [Mode 01]
tCL
CLK24
tCDO
D[7..0]
tCDO
Output
tCWO
tCWO
FWR#[01]
tPFWD
Figure 13-9. Fast Transfer Write Timing [MODE 01]
Page 13-8
EZ-USB Technical Reference Manual v1.10
tCL
CLK24
tDSU4
tDH4
Input
D[7..0]
tCRO
tCRO
FRD#[10]
Figure 13-10. Fast Transfer Read Timing [Mode 10]
tCL
CLK24
tCDO
tCDO
Output
D[7..0]
tCWO
tCWO
FWR#[10]
Figure 13-11. Fast Transfer Write Timing [Mode 10]
Chapter 13. EZ-USB AC/DC Parameters
Page 13-9
EZ-USB Technical Reference Manual
tCL
CLK24
tDSU4
tDH4
Input
D[7..0]
tCRO
tCRO
FRD#[11]
Figure 13-12. Fast Transfer Read Timing [Mode 11]
tCL
CLK24
tCDO
D[7..0]
tCDO
Output
tCWO
tCWO
FWR#[11]
tPFWD
Figure 13-13. Fast Transfer Write Timing [Mode 11]
Page 13-10
EZ-USB Technical Reference Manual v1.10
Chapter 14 EZ-USB Packaging
14.1
44-Pin PQFP Package
13.45
12.95
10.10
9.90
8.00 REF
44
34
33
1
0.80 BSC.
23
11
12
22
Figure 14-1. 44-Pin PQFP Package (Top View)
See Lead Detail
2.35 MAX
0.45
0.30
Figure 14-2. 44-Pin PQFP Package (Side View)
Chapter 14. EZ-USB Packaging
Page 14-1
1.95
2.10
EZ-USB Technical Reference Manual
0o~7o
0.25
0.10
0.23
0.13
0.95
0.65
1.60 TYP
Lead Detail: A(S=N/S)
Figure 14-3. 44-Pin PQFP Package (Detail View)
Page 14-2
EZ-USB Technical Reference Manual v1.10
14.2
80-Pin PQFP Package
24.10
23.70
20.05
19.95
0.80
64
3.0
65
41
40
0.80 BSC.
18.10
17.70
3.0
14.05
13.95
80 PQFP
80
25
24
1.00 Ref
1
Figure 14-4. 80-Pin PQFP Package (Top View)
See Lead
Detail
3.04 MAX
0.42
0.32
Figure 14-5. 80-Pin PQFP Package (Side View)
Chapter 14. EZ-USB Packaging
Page 14-3
EZ-USB Technical Reference Manual
0o~7o
0.25 Gage Plane
0o~10o
2.66
2.76
8 Places
12o REF.
Base Plane
Seating Plane
0.28
0.18
1.00
0.80
1.95 + 0.15
Detail "A"
Figure 14-6. 80-Pin PQFP Package (Detail View)
Page 14-4
EZ-USB Technical Reference Manual v1.10
14.3
48-Pin TQFP Package
See Lead
Detail
1.60 MAX
0.27
0.17
ALL DIMENSIONS IN MILLIMETERS.
Figure 14-7. 48-Pin TQFP Package (Side View)
9.00 BSC.
7.00
BSC.
48
37
36
1
0.50 BSC.
48 TQFP
25
12
13
24
ALL DIMENSIONS IN MILLIMETERS.
Figure 14-8. 48-Pin TQFP Package (Top View)
Chapter 14. EZ-USB Packaging
Page 14-5
EZ-USB Technical Reference Manual
1.35
1.45
0.08
0.20 R.
0.25 Gauge Plane
0o MIN.
Base Plane
Seating Plane
0.05
0.15
0.08 R.
MIN.
0 - 7o
0.20 MIN.
0.45
0.75
ALL DIMENSIONS IN MILLIMETERS.
1.00 REF.
48-Pin Lead Detail
Figure 14-9. 48-Pin TQFP Package (Detail View)
Page 14-6
EZ-USB Technical Reference Manual v1.10
Appendix A
CPU Introduction
A.1 Introduction
The EZ-USB’s CPU is an enhanced 8051. This appendix introduces the processor, its interface to
the EZ-USB logic, and describes architectural differences from a standard 8051. Figure A-1 is a
block diagram of the EZ-USB’s 8051-based CPU.
Crystal
Oscillator
Register
RAM
(256 bytes)
Serial Port1
Tim er2
Tim er1
Serial Port0
Tim er0
Interrupt
Control
I/O Ports*
8-bit CPU
Bus Control
* The EZ-USB fam ily im plem ents I/O ports differently than in the standard 8051
Figure A-1. EZ-USB CPU Features
Appendix A
A-1
EZ-USB Technical Reference Manual
A.2 8051 Enhancements
The EZ-USB uses the standard 8051 instruction set, so it’s supported by industry-standard 8051
compilers and assemblers. Instructions execute faster on the EZ-USB than on the standard 8051:
•
Wasted bus cycles are eliminated; an instruction cycle uses only four clocks, rather than
the standard 8051’s 12 clocks.
•
The EZ-USB’s CPU clock runs at 24MHz — twice the clock speed of the standard 8051.
In addition to speed improvements, the EZ-USB includes the following architectural enhancements to the CPU:
•
A second data pointer
•
A second USART
•
A third, 16-bit timer (TIMER2)
•
A high-speed external memory interface with a non-multiplexed 16-bit address bus
•
Eight additional interrupts (INT2-INT6, WAKEUP, T2, and USART1)
•
Variable MOVX timing to accommodate fast and slow RAM peripherals
•
Two Autopointers (auto-incrementing data pointers)
•
Vectored USB interrupts
•
Sleep mode with two wakeup sources
•
An I²C bus controller that runs at 100 or 400 KHz
•
EZ-USB-specific SFRs
•
Separate buffers for the SETUP and DATA portions of a USB CONTROL transfer
•
A hardware pointer for SETUP data, plus logic to process entire CONTROL transfers
automatically
•
Breakpoint facility
A.3 Performance Overview
The EZ-USB has been designed to offer increased performance by executing instructions in a
4-clock bus cycle, as opposed to the 12-clock bus cycle in the standard 8051 (see Figure A-2).
A-2
EZ-USB Technical Reference Manual v1.10
This shortened bus timing improves the instruction execution rate for most instructions by a factor
of three over the standard 8051 architectures.
Some instructions require a different number of instruction cycles on the EZ-USB than they do on
the standard 8051. In the standard 8051, all instructions except for MUL and DIV take one or two
instruction cycles to complete. In the EZ-USB, instructions can take between one and five instruction cycles to complete. However, due to the shortened bus timing of the EZ-USB, every instruction
executes faster than on a standard 8051, and the average speed improvement over the entire
instruction set is approximately 2.5×. Table A-1 catalogs the speed improvements.
Table A-1 EZ-USB Speed Compared to Standard 8051
Of the 246 EZ-USB opcodes...
150 execute at 3.0× standard speed
51 execute at 1.5× standard speed
43 execute at 2.0× standard speed
2 execute at 2.4× standard speed
Average Improvement:
2.5×
Note: Comparison is between EZ-USB and standard 8051
running at the same clock frequency.
Single-Byte, Single-Cycle Instruction Timing
PSEN
EZ-USB AD0-AD7
PORT2
4
XTAL1
12
Standard
8051
ALE
PSEN
AD0-AD7
PORT2
Figure A-2. EZ-USB to Standard 8051 Timing Comparison
Appendix A
A-3
EZ-USB Technical Reference Manual
A.4 Software Compatibility
The EZ-USB is object-code-compatible with the industry-standard 8051 microcontroller. That is,
object code compiled with an industry-standard 8051 compiler or assembler executes on the EZUSB and is functionally equivalent. However, because the EZ-USB uses a different instruction timing than the standard 8051, existing code with timing loops may require modification.
The EZ-USB instruction timing is identical to that of the Dallas Semiconductor DS80C320.
A.5 803x/805x Feature Comparison
Table A-2 provides a feature-by-feature comparison between the EZ-USB and several common
803x/805x devices.
Table A-2 Comparison Between EZ-USB and Other 803x/805x Devices
Feature
Clocks per instruction cycle
Program / Data Memory
Internal RAM
Intel
8031
8051
80C32
80C52
Dallas
DS80C320
12
12
12
12
4
4
-
4 KB ROM
-
8 KB ROM
-
8 KB RAM
256 bytes
256 bytes
256 bytes
256 bytes
128 bytes 128 bytes
Cypress
EZ-USB
Data Pointers
1
1
1
1
2
2
Serial Ports
1
1
1
1
2
2
16-bit Timers
2
2
3
3
3
3
Interrupt sources (internal and
external)
5
5
6
6
13
13
Stretch data-memory cycles
no
no
no
no
yes
yes
A.6 EZ-USB/DS80C320 Differences
Although the EZ-USB is similar to the DS80C320 in terms of hardware features and instruction
cycle timing, there are some important differences between the EZ-USB and the DS80C320.
A-4
EZ-USB Technical Reference Manual v1.10
A.6.1 Serial Ports
The EZ-USB does not implement serial port framing-error detection and does not implement slave
address comparison for multiprocessor communications. Therefore, the EZ-USB also does not
implement the following SFRs: SADDR0, SADDR1, SADEN0, and SADEN1.
A.6.2 Timer 2
The EZ-USB does not implement Timer 2 downcounting mode or the downcount enable bit
(TMOD2, Bit 0). Also, the EZ-USB does not implement Timer 2 output enable (T2OE) bit (TMOD2,
Bit 1). Therefore, the TMOD2 SFR is also not implemented in the EZ-USB.
The EZ-USB Timer 2 overflow output is active for one clock cycle. In the DS80C320, the Timer 2
overflow output is a square wave with a 50% duty cycle.
A.6.3 Timed Access Protection
The EZ-USB does not implement timed access protection and, therefore, does not implement the
TA SFR.
A.6.4 Watchdog Timer
The EZ-USB does not implement a watchdog timer.
A.6.5 Power Fail Detection
The EZ-USB does not implement a power fail detection circuit.
A.6.6 Port I/O
The EZ-USB’s port I/O implementation is significantly different from that of the DS80C320, mainly
because of the alternate functions shared with most of the I/O pins. See Chapter 4 EZ-USB Input/
Output.
Appendix A
A-5
EZ-USB Technical Reference Manual
A.6.7 Interrupts
Although the basic interrupt structure of the EZ-USB is similar to that of the DS80C320, five of the
interrupt sources are different:
Table A-3 Differences between EZ-USB and DS80C320 Interrupts
Interrupt
Priority
Dallas DS80C320
Cypress EZ-USB
0
Power Fail
RESUME (USB Wakeup)
8
External Interrupt 2
USB
9
External Interrupt 3
I²C Bus
12
Watchdog Timer
External Interrupt 6
For more information, refer to Appendix C.
A.7 EZ-USB Register Interface
The EZ-USB peripheral logic (USB, I/O ports, I²C controller, etc.) is controlled via a set of memory
mapped registers and buffers at addresses 0x7B40 through 0x7FFF. These registers and their
functions are described throughout this manual. A full description of every EZ-USB register
appears in Chapter 12, "EZ-USB Registers."
A.8 EZ-USB Internal RAM
0xFF
Upper 128
SFR Space
0x80
0x7F
Indirect Addr
Direct Addr
0x00
Direct Addr
Lower 128
Figure A-3. EZ-USB Internal Data RAM
Like the standard 8051, the EZ-USB contains 128 bytes of Internal Data RAM at addresses
0x00-0x7F and a partially populated SFR space at addresses 0x80-0xFF. An additional 128 indirectly-addressed bytes of Internal Data RAM (sometimes called “IDATA”) are also available at
addresses 0x80-0xFF.
A-6
EZ-USB Technical Reference Manual v1.10
All other on-chip EZ-USB RAM (program/data memory, endpoint buffer memory, and the EZ-USB
control registers) is addressed as though it were off-chip 8051 memory. EZ-USB firmware reads or
writes these bytes as data using the MOVX (“move external”) instruction, even though the EZ-USB
RAM and register set is actually inside the EZ-USB chip. Off-chip memory attached to the EZ-USB
address and data buses (80-pin package only) can also be accessed by the MOVX instruction. EZUSB logic encodes its memory strobe and select signals (RD, WR, CS, OE, and PSEN) to eliminate the need for external logic to separate the on-chip and off-chip memory spaces; see Chapter
3, "EZ-USB Memory.".
A.9 I/O Ports
The EZ-USB implements I/O ports differently than a standard 8051, as described in Chapter 4
EZ-USB Input/Output.
The EZ-USB has up to three 8-bit wide, bidirectional I/O ports. Each port is associated with three
registers:
•
An “OEx” register, which sets the input/output direction of each of the 8 port pins
(0 = input, 1 = output).
•
An “OUTx” register. Values written to OUTx appear on the pins configured as outputs.
•
A “PINSx” register. Values read from PINSx indicate the states of the 8 pins, regardless of
input/output configuration.
Most I/O pins have alternate functions which are selected using configuration registers. When an
alternate configuration is selected for an I/O pin, the corresponding OEx bit is ignored (see Section
4.2). The default (power-on reset) state of all I/O ports is: alternate configurations off, all I/O pins
configured as inputs.
A.10 Interrupts
All standard 8051 interrupts, plus additional interrupts, are supported by the EZ-USB. Table A-4
lists the EZ-USB interrupts.
Appendix A
A-7
EZ-USB Technical Reference Manual
Table A-4 EZ-USB Interrupts
Standard 8051
Interrupts
Additional
EZ-USB
Interrupts
INT0
Source
Pin PC2 / INT0
INT1
Pin PC3 / INT1
Timer 0
Internal, Timer 0
Timer 1
Internal, Timer 1
Tx0 & Rx0
Internal, USART0
INT2
Internal, USB
INT3
Internal, I²C Bus Controller
INT4
Pin PB4/INT4
INT5
Pin PB5/INT5
INT6
Pin PB6/INT6
WAKEUP
Pin WAKEUP or USB Core
Tx1 & Rx1
Internal, USART1
Timer 2
Internal, Timer 2
The EZ-USB uses INT2 for 21 different USB interrupts. To help determine which interrupt is active,
the EZ-USB provides a feature called Autovectoring, which dynamically changes the address
pointed to by the “jump” instruction at the INT2 vector address. This second level of vectoring
automatically transfers control to the appropriate USB interrupt service routine (ISR). The EZ-USB
interrupt system, including a full description of the Autovector mechanism, is the subject of Chapter 9, "EZ-USB Interrupts."
A.11 Power Control
The EZ-USB implements a low-power mode that allows it to be used in USB bus-powered devices
(which are required by the USB specification to draw no more than 500 µA when suspended) and
other low-power applications. The mechanism by which the EZ-USB enters and exits this lowpower mode is described in detail in Chapter 11 EZ-USB Power Management.
A.12 Special Function Registers (SFR)
The EZ-USB was designed to keep coding as standard as possible, to allow easy integration of
existing 8051 software development tools. The EZ-USB SFR registers are summarized in Table A5. Standard 8051 SFRs are shown in normal type and EZ-USB-added SFRs are shown in bold
type. Full details of the SFRs can be found in Chapter 12, "EZ-USB Registers."
A-8
EZ-USB Technical Reference Manual v1.10
Table A-5 EZ-USB Special Function Registers (SFR)
x
8x
9x
SP
EXIF
2
DPL0
MPAGE
3
DPH0
4
DPL1
5
DPH1
6
DPS
7
PCON
Ax
Bx
0
1
Cx
Dx
Ex
Fx
SCON1
PSW
ACC
B
EICON
EIE
EIP
SBUF1
8
TCON
SCON0
9
TMOD
SBUF0
A
TL0
RCAP2L
B
TL1
RCAP2H
C
TH0
TL2
D
TH1
TH2
E
CKCON
F
SPC_FNC
IE
IP
T2CON
All unlabed SFRs are reserved.
In Table A-6, SFR bit positions that contain a 0 or a 1 cannot be written to and, when read, always
return the value shown (0 or 1). SFR bit positions that contain “-” are available but not used. Table
A-7 lists the reset values for the SFRs.
Detailed descriptions of the SFRs appear with the associated hardware descriptions in Appendix C
and in Chapter 12, "EZ-USB Registers."
Appendix A
A-9
EZ-USB Technical Reference Manual
Table A-6 Special Function Registers
Register
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Addr
SP
81h
DPL0
82h
DPH0
83h
DPL1(1)
84h
DPH1(1)
85h
DPS(1)
0
0
0
0
0
0
0
SEL
86h
PCON
SMOD0
-
1
1
GF1
GF0
STOP
IDLE
87h
TCON
TF1
TR1
TF0
TR0
IE1
IT1
IE0
IT0
88h
TMOD
GATE
C/T
M1
M0
GATE
C/T
M1
M0
89h
TL0
8Ah
TL1
8Bh
TH0
8Ch
TH1
8Dh
CKCON(1)
-
-
T2M
T1M
T0M
MD2
MD1
MD0
8Eh
SPC_FNC(1)
0
0
0
0
0
0
0
WRS
8Fh
EXIF(1)
IE5
IE4
I2CINT
USBINT
1
0
0
0
91h
92h
MPAGE(1)
SCON0
SM0_0
SM1_0
SM2_0
REN_0
TB8_0
RB8_0
TI_0
RI_0
SBUF0
98h
99h
IE
EA
ES1
ET2
ES0
ET1
EX1
ET0
EX0
IP
1
PS1
PT2
PS0
PT1
PX1
PT0
PX0
B8h
SCON1(1)
SM0_1
SM1_1
SM2_1
REN_1
TB8_1
RB8_1
TI_1
RI_1
C0h
C1h
SBUF1(1)
T2CON
A8h
TF2
EXF2
RCLK
TCLK
EXEN2
TR2
C/T2
CP/RL2
C8h
RCAP2L
CAh
RCAP2H
CBh
TL2
CCh
TH2
CDh
PSW
CY
AC
F0
RS1
RS0
OV
F1
P
D0h
EICON(1)
SMOD1
1
ERESI
RESI
INT6
0
0
0
D8h
ACC
EIE(1)
E0H
1
1
1
EWDI
EX5
EX4
EI2C
EUSB
1
1
1
PX6
PX5
PX4
PI2C
PUSB
B
E8h
F0h
EIP(1)
(1)
A - 10
F8h
Not part of standard 8051 architecture.
EZ-USB Technical Reference Manual v1.10
Table A-7 Special Function Register Reset Values
Register
SP
Bit 7
0
Bit 6
0
Bit 5
0
Bit 4
0
Bit 3
0
Bit 2
1
Bit 1
1
Bit 0
1
Addr
81h
DPL0
0
0
0
0
0
0
0
0
82h
DPH0
0
0
0
0
0
0
0
0
83h
DPL1(1)
0
0
0
0
0
0
0
0
84h
DPH1(1)
0
0
0
0
0
0
0
0
85h
DPS(1)
0
0
0
0
0
0
0
0
86h
PCON
0
0
1
1
0
0
0
0
87h
TCON
0
0
0
0
0
0
0
0
88h
TMOD
0
0
0
0
0
0
0
0
89h
TL0
0
0
0
0
0
0
0
0
8Ah
TL1
0
0
0
0
0
0
0
0
8Bh
TH0
0
0
0
0
0
0
0
0
8Ch
TH1
0
0
0
0
0
0
0
0
8Dh
CKCON(1)
0
0
0
0
0
0
0
1
8Eh
SPC_FNC(1)
0
0
0
0
0
0
0
0
8Fh
EXIF(1)
0
0
0
0
1
0
0
0
91h
MPAGE(1)
0
0
0
0
0
0
0
0
92h
SCON0
0
0
0
0
0
0
0
0
98h
SBUF0
0
0
0
0
0
0
0
0
99h
IE
0
0
0
0
0
0
0
0
A8h
IP
1
0
0
0
0
0
0
0
B8h
SCON1(1)
0
0
0
0
0
0
0
0
C0h
SBUF1(1)
0
0
0
0
0
0
0
0
C1h
T2CON
0
0
0
0
0
0
0
0
C8h
RCAP2L
0
0
0
0
0
0
0
0
CAh
RCAP2H
0
0
0
0
0
0
0
0
CBh
TL2
0
0
0
0
0
0
0
0
CCh
TH2
0
0
0
0
0
0
0
0
CDh
PSW
0
0
0
0
0
0
0
0
D0h
EICON(1)
0
1
0
0
0
0
0
0
D8h
ACC
0
0
0
0
0
0
0
0
E0H
EIE(1)
1
1
1
0
0
0
0
0
E8h
B
0
0
0
0
0
0
0
0
F0h
EIP(1)
1
1
1
0
0
0
0
0
F8h
(1)
Not part of standard 8051 architecture.
Appendix A
A - 11
EZ-USB Technical Reference Manual
A.13 External Address/Data Buses
The 80-pin version of the EZ-USB provides external, non-multiplexed 16-bit address and 8-bit
data buses. This differs from the standard 8051, which multiplexes eight pins among three
sources: I/O port 0, the external data bus, and the low byte of the external address bus.
A standard 8051 system with external memory requires a demultiplexing address latch, strobed by
the 8051 ALE (Address Latch Enable) pin. The external latch is not required by the EZ-USB chip,
and no ALE signal is provided. In addition to eliminating the need for this external latch, the nonmultiplexed EZ-USB bus saves one cycle per memory-fetch and allows external memory to be
connected without sacrificing I/O pins.
The EZ-USB is the sole master of the bus, providing read and write signals to the off-chip memory.
The address bus is output-only, and cannot be floated.
A.14 Reset
The various EZ-USB resets and their effects are described in Chapter 10, "EZ-USB Resets.".
A - 12
EZ-USB Technical Reference Manual v1.10
Appendix B
CPU Architectural Overview
B.1 Internal Data RAM
As shown in Figure B-1, the EZ-USB’s Internal Data RAM is divided into three distinct regions: the
“Lower 128”, the “Upper 128”, and “SFR Space”. The Lower 128 and Upper 128 are general-purpose RAM; the SFR Space contains EZ-USB control and status registers.
Lower 128
Indirect addressing only
0x7F
0xFF
GeneralPurpose
0x30
0x2F 78
Register
Bank Select
(PSW.4:3)
Upper 128
....
10
0
0
SFR Space
7
Bit-Addressable
RAM
....
11
0xFF
0x80
0x7F
0x80
Lower 128
0
0x20 0
0x1F R0-R7 (Bank 3)
0x18
0x17
R0-R7 (Bank 2)
0x10
0x0F R0-R7 (Bank 1)
0x08
0x07
R0-R7 (Bank 0)
0x00
Direct addressing
only
0x00
Direct or indirect addressing
Figure B-1. Internal Data RAM Organization
B.1.1 The Lower 128
The Lower 128 occupies Internal Data RAM locations 0x00-0x7F. All of the Lower 128 may be
accessed as general-purpose RAM, using either direct or indirect addressing (for more information
on the EZ-USB addressing modes, see Section B.2, "Instruction Set").
Appendix B
B - 13
EZ-USB Technical Reference Manual
Two segments of the Lower 128 may additionally be accessed in other ways.
•
Locations 0x00-0x1F comprise four banks of 8 registers each, numbered R0 through R7.
The current bank is selected via the “register-select” bits (RS1:RS0) in the PSW specialfunction register; code which references registers R0-R7 will access them only in the currently-selected bank.
•
Locations 0x20-0x2F are bit-addressable. Each of the 128 bits in this segment may be
individually addressed, either by its bit address (0x00 to 0x7F) or by reference to the byte
which contains it (0x20.0 to 0x2F.7).
B.1.2 The Upper 128
The Upper 128 occupies Internal Data RAM locations 0x80-0xFF; all 128 bytes may be accessed
as general-purpose RAM, but only by using indirect addressing (for more information on the EZUSB addressing modes, see Section B.2, "Instruction Set").
Since the EZ-USB’s stack is internally accessed using indirect addressing, it’s a good idea to put
the stack in the Upper 128; this frees the more-efficiently-accessed Lower 128 for General-Purpose use.
B.1.3 SFR (Special Function Register) Space
The SFR Space, like the Upper 128, is accessed at Internal Data RAM locations 0x80-0xFF. The
EZ-USB keeps SFR Space separate from the Upper 128 by using different addressing modes to
access the two regions: SFRs may only be accessed using direct addressing, and the Upper 128
may only be accessed using indirect addressing.
The SFR Space contains EZ-USB control and status registers; an overview is in Section B.2.4,
"Special Function Registers", and a full description of all the SFRs is in Chapter 12 "EZ-USB Registers".
The sixteen SFRs at locations 0x80, 0x88, ...., 0xF0, 0xF8 are bit-addressable. Each of the 128
bits in these registers may be individually addressed, either by its bit address (0x80 to 0xFF) or by
reference to the byte which contains it (e.g., 0x80.0, 0xC8.7, etc.).
B.2 Instruction Set
All EZ-USB instructions are binary-code-compatible with the standard 8051. The EZ-USB instructions affect bits, flags, and other status functions just as the 8051 instructions do. Instruction timing, however, is different both in terms of the number of clock cycles per instruction cycle and the
number of instruction cycles used by each instruction.
Table B-2 lists the EZ-USB instruction set and the number of instruction cycles required to complete each instruction. Table B-1 defines the symbols and mnemonics used in Table B-2.
B - 14
EZ-USB Technical Reference Manual v1.10
Table B-1 Legend for Instruction Set Table
Symbol
Function
A
Accumulator
Rn
Register (R0–R7, in the bank selected by RS1:RS0)
direct
Internal RAM location (0x00 - 0x7F in the “Lower 128”, or 0x80 - 0xFF in “SFR” space)
@Ri
Internal RAM location (0x00 - 0x7F in the “Lower 128”, or 0x80 - 0xFF in the “Upper 128”)
pointed to by R0 or R1
rel
Program-memory offset (-128 to +127 bytes relative to the first byte of the following
instruction). Used by conditional jumps and SJMP.
bit
Bit address (0x20 - x2F in the “Lower 128,” and SFRs 0x80, 0x88, ...., 0xF0, 0xF8)
#data
8-bit constant (0 - 255)
#data16
16-bit constant (0 - 65535)
addr16
16-bit destination address; used by LCALL and LJMP, which branch anywhere in program
memory
addr11
11-bit destination address; used by ACALL and AJMP, which branch only within the current 2K page of program memory (i.e., the upper 5 address bits are copied from the PC)
PC
Program Counter; holds the address of the currently-executing instruction. For the purposes of “ACALL”, “AJMP”, and “MOVC A,@A+PC” instructions, the PC holds the
address of the first byte of the instruction following the currently-executing instruction.
Table B-2 EZ-USB Instruction Set
Mnemonic
Description
Bytes Cycles
PSW
Flags
Affected
Opcode
(Hex)
28-2F
Arithmetic
ADD A, Rn
Add register to A
1
1
CY OV AC
ADD A, direct
Add direct byte to A
2
2
CY OV AC
25
ADD A, @Ri
Add data memory to A
1
1
CY OV AC
26-27
ADD A, #data
Add immediate to A
2
2
CY OV AC
24
ADDC A, Rn
Add register to A with carry
1
1
CY OV AC
38-3F
ADDC A, direct
Add direct byte to A with carry
2
2
CY OV AC
35
ADDC A, @Ri
Add data memory to A with carry
1
1
CY OV AC
36-37
ADDC A, #data
Add immediate to A with carry
2
2
CY OV AC
34
SUBB A, Rn
Subtract register from A with borrow
1
1
CY OV AC
98-9F
SUBB A, direct
Subtract direct byte from A with borrow
2
2
CY OV AC
95
SUBB A, @Ri
Subtract data memory from A with borrow
1
1
CY OV AC
96-97
SUBB A, #data
Subtract immediate from A with borrow
2
2
CY OV AC
94
INC A
Increment A
1
1
04
INC Rn
Increment register
1
1
08-0F
INC direct
Increment direct byte
2
2
05
Appendix B
B - 15
EZ-USB Technical Reference Manual
Table B-2 EZ-USB Instruction Set (Continued)
Mnemonic
Description
Bytes Cycles
PSW
Flags
Affected
Opcode
(Hex)
INC @ Ri
Increment data memory
1
1
06-07
DEC A
Decrement A
1
1
14
DEC Rn
Decrement Register
1
1
18-1F
DEC direct
Decrement direct byte
2
2
15
DEC @Ri
Decrement data memory
1
1
16-17
INC DPTR
Increment data pointer
1
3
A3
MUL AB
Multiply A and B (unsigned; product in B:A)
1
5
CY=0 OV
A4
DIV AB
Divide A by B
(unsigned; quotient in A, remainder in B)
1
5
CY=0 OV
84
DA A
Decimal adjust A
1
1
CY
D4
Logical
ANL, Rn
AND register to A
1
1
58-5F
ANL A, direct
AND direct byte to A
2
2
55
ANL A, @Ri
AND data memory to A
1
1
56-57
ANL A, #data
AND immediate to A
2
2
54
ANL direct, A
AND A to direct byte
2
2
52
ANL direct, #data
AND immediate data to direct byte
3
3
53
ORL A, Rn
OR register to A
1
1
48-4F
ORL A, direct
OR direct byte to A
2
2
45
ORL A, @Ri
OR data memory to A
1
1
46-47
ORL A, #data
OR immediate to A
2
2
44
ORL direct, A
OR A to direct byte
2
2
42
ORL direct, #data
OR immediate data to direct byte
3
3
43
XRL A, Rn
Exclusive-OR register to A
1
1
68-6F
XRL A, direct
Exclusive-OR direct byte to A
2
2
65
XRL A, @Ri
Exclusive-OR data memory to A
1
1
66-67
XRL A, #data
Exclusive-OR immediate to A
2
2
64
XRL direct, A
Exclusive-OR A to direct byte
2
2
62
XRL direct, #data
Exclusive-OR immediate to direct byte
3
3
63
CLR A
Clear A
1
1
E4
CPL A
Complement A
1
1
F4
SWAP A
Swap nibbles of a
1
1
C4
RL A
Rotate A left
1
1
23
RLC A
Rotate A left through carry
1
1
RR A
Rotate A right
1
1
RRC A
Rotate A right through carry
1
1
1
1
CY
33
03
CY
13
Data Transfer
MOV A, Rn
B - 16
Move register to A
E8-EF
EZ-USB Technical Reference Manual v1.10
Table B-2 EZ-USB Instruction Set (Continued)
Mnemonic
Description
Bytes Cycles
PSW
Flags
Affected
Opcode
(Hex)
MOV A, direct
Move direct byte to A
2
2
E5
MOV A, @Ri
Move data byte at Ri to A
1
1
E6-E7
MOV A, #data
Move immediate to A
2
2
74
MOV Rn, A
Move A to register
1
1
F8-FF
MOV Rn, direct
Move direct byte to register
2
2
A8-AF
MOV Rn, #data
Move immediate to register
2
2
78-7F
MOV direct, A
Move A to direct byte
2
2
F5
MOV direct, Rn
Move register to direct byte
2
2
88-8F
MOV direct, direct
Move direct byte to direct byte
3
3
85
MOV direct, @Ri
Move data byte at Ri to direct byte
2
2
86-87
MOV direct, #data
Move immediate to direct byte
3
3
75
MOV @Ri, A
MOV A to data memory at address Ri
1
1
F6-F7
MOV @Ri, direct
Move direct byte to data memory
at address Ri
2
2
A6-A7
MOV @Ri, #data
Move immediate to data memory
at address Ri
2
2
76-77
3
3
90
MOV DPTR, #data16 Move 16-bit immediate to data pointer
MOVC A, @A+DPTR Move code byte at address DPTR+A to A
1
3
93
MOVC A, @A+PC
Move code byte at address PC+A to A
1
3
83
MOVX A, @Ri
Move external data at address Ri to A
1
2-9*
E2-E3
MOVX A, @DPTR
Move external data at address DPTR to A
1
2-9*
E0
MOVX @Ri, A
Move A to external data at address Ri
1
2-9*
F2-F3
MOVX @DPTR, A
Move A to external data at address DPTR
1
2-9*
F0
PUSH direct
Push direct byte onto stack
2
2
C0
POP direct
Pop direct byte from stack
2
2
D0
XCH A, Rn
Exchange A and register
1
1
C8-CF
XCH A, direct
Exchange A and direct byte
2
2
C5
XCH A, @Ri
Exchange A and data memory
at address Ri
1
1
C6-C7
XCHD A, @Ri
Exchange the low-order nibbles
of A and data memory at address Ri
1
1
D6-D7
* Number of cycles is user-selectable. See Section B.2.2. "Stretch Memory Cycles (Wait States)".
Boolean
CLR C
Clear carry
1
1
CLR bit
Clear direct bit
2
2
SETB C
Set carry
1
1
SETB bit
Set direct bit
2
2
CPL C
Complement carry
1
1
Appendix B
CY=0
C3
C2
CY=1
D3
D2
CY
B3
B - 17
EZ-USB Technical Reference Manual
Table B-2 EZ-USB Instruction Set (Continued)
Mnemonic
Description
Bytes Cycles
CPL bit
Complement direct bit
2
2
ANL C, bit
AND direct bit to carry
2
2
PSW
Flags
Affected
Opcode
(Hex)
B2
CY
82
ANL C, /bit
AND inverse of direct bit to carry
2
2
CY
B0
ORL C, bit
OR direct bit to carry
2
2
CY
72
ORL C, /bit
OR inverse of direct bit to carry
2
2
CY
A0
MOV C, bit
Move direct bit to carry
2
2
CY
A2
MOV bit, C
Move carry to direct bit
2
2
92
Branching
ACALL addr11
Absolute call to subroutine
2
3
11-F1
LCALL addr16
Long call to subroutine
3
4
12
RET
Return from subroutine
1
4
22
RETI
Return from interrupt
1
4
32
AJMP addr11
Absolute jump unconditional
2
3
01-E1
LJMP addr16
Long jump unconditional
3
4
02
SJMP rel
Short jump (relative address)
2
3
80
JC rel
Jump if carry = 1
2
3
40
JNC rel
Jump if carry = 0
2
3
50
JB bit, rel
Jump if direct bit = 1
3
4
20
JNB bit, rel
Jump if direct bit = 0
3
4
30
JBC bit, rel
Jump if direct bit = 1, then clear the bit
3
4
10
JMP @ A+DPTR
Jump indirect to address DPTR+A
1
3
73
JZ rel
Jump if accumulator = 0
2
3
60
JNZ rel
Jump if accumulator is non-zero
2
3
CJNE A, direct, rel
Compare A to direct byte; jump if not equal
3
4
CY
CJNE A, #d, rel
Compare A to immediate; jump if not equal
3
4
CY
B4
CJNE Rn, #d, rel
Compare register to immediate;
jump if not equal
3
4
CY
B8-BF
CJNE @ Ri, #d, rel
Compare data memory to immediate;
jump if not equal
3
4
CY
B6-B7
DJNZ Rn, rel
Decrement register; jump if not zero
2
3
D8-DF
DJNZ direct, rel
Decrement direct byte; jump if not zero
3
4
D5
NOP
No operation
1
1
00
70
B5
Miscellaneous
There is an additional reserved opcode (A5) that performs the same function as NOP.
All mnemonics are copyright 1980, Intel Corporation.
B - 18
EZ-USB Technical Reference Manual v1.10
B.2.1 Instruction Timing
Instruction cycles in the EZ-USB are 4 clock cycles in length, as opposed to the 12 clock cycles per
instruction cycle in the standard 8051. For full details of the instruction-cycle timing differences
between the EZ-USB and the standard 8051, see Section A.3, "Performance Overview".
In the standard 8051, all instructions except for MUL and DIV take one or two instruction cycles to
complete. In the EZ-USB, instructions can take between one and five instruction cycles to complete. For calculating the timing of software loops, etc., use the “Cycles” column from Table B-2.
The “Bytes” column indicates the number of bytes occupied by each instruction.
By default, the EZ-USB’s timer/counters run at 12 clock cycles per increment so that timer-based
events have the same timing as with the standard 8051. The timers can also be configured to run
at 4 clock cycles per increment to take advantage of the higher speed of the EZ-USB’s CPU.
B.2.2 Stretch Memory Cycles (Wait States)
The EZ-USB can execute a MOVX instruction in as few as 2 instruction cycles. However, it is
sometimes desirable to stretch this value (for example to access slow memory or slow memorymapped peripherals such as USARTs or LCDs). The EZ-USB’s “stretch memory cycle” feature
enables EZ-USB firmware to adjust the speed of data memory accesses (program-memory code
fetches are not affected).
The three LSBs of the Clock Control Register (CKCON, at SFR location 0x8E) control the stretch
value; stretch values between zero and seven may be used. A stretch value of zero adds zero
instruction cycles, resulting in MOVX instructions which execute in two instruction cycles. A stretch
value of seven adds seven instruction cycles, resulting in MOVX instructions which execute in nine
instruction cycles. The stretch value can be changed dynamically under program control.
At power-on-reset, the stretch value defaults to one (three-cycle MOVX); for the fastest data memory access, EZ-USB software must explicitly set the stretch value to zero. The stretch value affects
only data memory access (not program memory).
The stretch value affects the width of the read/write strobe and all related timing. Using a higher
stretch value results in a wider read/write strobe, which allows the memory or peripheral more time
to respond.
Table B-3 lists the data memory access speeds for stretch values zero through seven. MD2-0 are
the three LSBs of the Clock Control Register (CKCON.2-0). The strobe width timing shown is typical.
Appendix B
B - 19
EZ-USB Technical Reference Manual
Table B-3 Data Memory Stretch Values
MOVX
Read/Write
Instruction Strobe Width
Cycles
(Clocks)
Read/Write
Strobe Width
(nanoseconds)
MD2
MD1
MD0
0
0
0
2
2
83.3 ns
0
0
1
3 (default)
4
167 ns
0
1
0
4
8
333 ns
0
1
1
5
12
500 ns
1
0
0
6
16
667 ns
1
0
1
7
20
833 ns
1
1
0
8
24
1000 ns
1
1
1
9
28
1167 ns
B.2.3 Dual Data Pointers
The EZ-USB employs dual data pointers to accelerate data memory block moves. The standard
8051 data pointer (DPTR) is a 16-bit pointer used to address external data RAM or peripherals.
The EZ-USB maintains the standard data pointer as DPTR0 at the standard SFR locations 0x82
(DPL0) and 0x83 (DPH0); it is not necessary to modify existing code to use DPTR0.
The EZ-USB adds a second data pointer (DPTR1) at SFR locations 0x84 (DPL1) and 0x85
(DPH1). The SEL bit (bit 0 of the DPTR Select Register, DPS, at SFR 0x86), selects the active
pointer. When SEL = 0, instructions that use the DPTR will use DPL0:DPH0. When SEL = 1,
instructions that use the DPTR will use DPL1:DPH1. No other bits of the DPS SFR are used.
All DPTR-related instructions use the data pointer selected by the SEL Bit. Switching between the
two data pointers by toggling the SEL bit relieves EZ-USB firmware from the burden of saving
source and destination addresses when doing a block move; therefore, using dual data pointers
provides significantly increased efficiency when moving large blocks of data.
The fastest way to toggle the SEL bit between the two data pointers is via the “INC DPS” instruction, which toggles bit 0 of DPS between 0 and 1.
The SFR locations related to the dual data pointers are:
0x82DPL0
0x83DPH0
0x84DPL1
0x85DPH1
0x86DPS
B - 20
DPTR0 low byte
DPTR0 high byte
DPTR1 low byte
DPTR1 high byte
DPTR Select (Bit 0)
EZ-USB Technical Reference Manual v1.10
B.2.4 Special Function Registers
The four SFRs listed below are related to CPU operation and program execution. Except for the
Stack Pointer SP, each of the registers is bit addressable.
0x81
0xD0
0xE0
0xF0
SP
PSW
ACC
B
Stack Pointer
Program Status Word
Accumulator Register
B Register
Table B-4 lists the functions of the PSW bits.
Table B-4 PSW Register - SFR 0xD0
Bit
PSW.7
Function
CY - Carry flag. This is the unsigned carry bit. The CY flag is set when an arithmetic operation
results in a carry from bit 7 to bit 8, and cleared otherwise. In other words, it acts as a virtual bit
8. The CY flag is cleared on multiplication and division. See the “PSW Flags Affected” column in
Table B-2.
PSW.6
AC - Auxiliary carry flag. Set to 1 when the last arithmetic operation resulted in a carry into (during addition) or borrow from (during subtraction) the high order nibble, otherwise cleared to 0 by
all arithmetic operations. See the “PSW Flags Affected” column in Table B-2.
PSW.5
F0 - User flag 0. Available to EZ-USB firmware for general purpose.
PSW.4
RS1 - Register bank select bit 1.
PSW.3
RS0 - Register bank select bit 0.
RS1:RS0 select a register bank in internal RAM:
RS1 RS0
0
0
0
1
1
0
1
1
Bank Selected
Register bank 0, addresses 0x00-0x07
Register bank 1, addresses 0x08-0x0F
Register bank 2, addresses 0x10-0x17
Register bank 3, addresses 0x18-0x1F
PSW.2
OV - Overflow flag. This is the signed carry bit. The OV flag is set when a positive sum exceeds
0x7F or a negative sum (in two’s complement notation) exceeds 0x80. After a multiply, OV = 1 if
the result of the multiply is greater than 0xFF. After a divide, OV = 1 if a divide-by-0 occurred.
See the “PSW Flags Affected” column in Table B-2.
PSW.1
F1 - User flag 1. Available to EZ-USB firmware for general purpose.
PSW.0
P - Parity flag. Contains the modulo-2 sum of the 8 bits in the accumulator (i.e., set to 1 when the
accumulator contains an odd number of “1” bits, set to 0 when the accumulator contains an even
number of “1” bits).
Appendix B
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EZ-USB Technical Reference Manual
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EZ-USB Technical Reference Manual v1.10
Appendix C
EZ-USB Peripherals
C.1 Introduction
This chapter provides technical data about the EZ-USB peripheral operation and timing. The topics
are:
•
Timers/Counters
•
Serial Interface
•
Interrupts
C.2 Timers/Counters
The EZ-USB includes three timer/counters (Timer 0, Timer 1, and Timer 2). Each timer/counter can
operate either as a timer with a clock rate based on the EZ-USB’s internal clock (CLK24) or as an
event counter clocked by the T0 pin (Timer 0), T1 pin (Timer 1), or the T2 pin (Timer 2). Timers 1
and 2 may be used for baud clock generation for the serial interface (see Section C.3 for details of
the serial interface).
Each timer/counter consists of a 16-bit register that is accessible to software as two SFRs:
•
Timer 0 — TH0 and TL0
•
Timer 1 — TH1 and TL1
•
Timer 2 — TH2 and TL2
C.2.1 803x/805x Compatibility
The implementation of the timers/counters is similar to that of the Dallas Semiconductor
DS80C320. Table C-1 summarizes the differences in timer/counter implementation between the
Intel 8051, the Dallas Semiconductor DS80C320, and the EZ-USB.
Appendix C
C - 23
EZ-USB Technical Reference Manual
Table C-1 Timer/Counter Implementation Comparison
Feature
Intel 8051
Dallas DS80C320
2
3
Timer 0/1 overflow
available as output signals
No
No
Yes; T0OUT, T1OUT
(one CLK24 pulse)
Timer 2 output enable
n/a
Yes
No
Timer 2 down-count enable
n/a
Yes
No
Timer 2 overflow
available as output signal
n/a
Yes
Yes; T2OUT (one CLK24
pulse)
Number of timers
EZ-USB
3
C.2.2 Timers 0 and 1
Timers 0 and 1 operate in four modes, as controlled through the TMOD SFR (Table C-2) and the
TCON SFR (Table C-3). The four modes are:
•
13-bit timer/counter (mode 0)
•
16-bit timer/counter (mode 1)
•
8-bit counter with auto-reload (mode 2)
•
Two 8-bit counters (mode 3, Timer 0 only)
C.2.2.1 Mode 0, 13-Bit Timer/Counter — Timer 0 and Timer 1
Mode 0 operation is illustrated in Figure C-1.
In mode 0, the timer is configured as a 13-bit counter that uses bits 0-4 of TL0 (or TL1) and all 8
bits of TH0 (or TH1). The timer enable bit (TR0/TR1) in the TCON SFR starts the timer. The C/T
Bit selects the timer/counter clock source: either CLK24 or the T0/T1 pins.
The timer counts transitions from the selected source as long as the GATE Bit is 0, or the GATE
Bit is 1 and the corresponding interrupt pin (INT0 or INT1) is 1.
When the 13-bit count increments from 0x1FFF (all ones), the counter rolls over to all zeros, the
TF0 (or TF1) Bit is set in the TCON SFR, and the T0OUT (or T1OUT) pin goes high for one clock
cycle.
The upper 3 bits of TL0 (or TL1) are indeterminate in mode 0 and should be ignored.
C - 24
EZ-USB Technical Reference Manual v1.10
Divide by 12
CLK24
T0M (or T1M)
0
1
0
CLK
C/ T
Divide by 4
TL0 (or TL1)
7
4
0
1
Mode 0
T0 (or T1) pin
Mode 1
TR0 (or TR1)
0
TH0 (or TH1) 7
GATE
INT0 (or
INT1) pin
TF0 (or TF1)
INT
To Serial Port
(Timer 1 only)
Figure C-1. Timer 0/1 - Modes 0 and 1
C.2.2.2 Mode 1, 16-Bit Timer/Counter — Timer 0 and Timer 1
In mode 1, the timer is configured as a 16-bit counter. As illustrated in Figure C-1, all 8 bits of the
LSB Register (TL0 or TL1) are used. The counter rolls over to all zeros when the count increments
from 0xFFFF. Otherwise, mode 1 operation is the same as mode 0.
Appendix C
C - 25
EZ-USB Technical Reference Manual
Table C-2 TMOD Register — SFR 0x89
Bit
Function
TMOD.7
GATE1 - Timer 1 gate control. When GATE1 = 1, Timer 1 will clock only when INT1 = 1 and
TR1 (TCON.6) = 1. When GATE1 = 0, Timer 1 will clock only when TR1 = 1, regardless of
the state of INT1.
TMOD.6
C/T1 - Counter/Timer select. When C/T1 = 0, Timer 1 is clocked by CLK24/4 or CLK24/12,
depending on the state of T1M (CKCON.4). When C/T1 = 1, Timer 1 is clocked by high-tolow transitions on the T1 pin.
TMOD.5
M1 - Timer 1 mode select bit 1.
TMOD.4
M0 - Timer 1 mode select bit 0.
M1
0
0
1
1
M0
0
1
0
1
Mode
Mode 0 : 13-bit counter
Mode 1 : 16-bit counter
Mode 2 : 8-bit counter with auto-reload
Mode 3 : Timer 1 stopped
TMOD.3
GATE0 - Timer 0 gate control, When GATE0 = 1, Timer 0 will clock only when INT0 = 1 and
TR0 (TCON.4) = 1. When GATE0 = 0, Timer 0 will clock only when TR0 = 1, regardless of
the state of INT0.
TMOD.2
C/T0 - Counter/Timer select. When C/T0 = 0, Timer 0 is clocked by CLK24/4 or CLK24/12,
depending on the state of T0M (CKCON.3). When C/T0 = 1, Timer 0 is clocked by high-tolow transitions on the T0 pin.
TMOD.1
M1 - Timer 0 mode select bit 1.
TMOD.0
M0 - Timer 0 mode select bit 0.
M1
0
0
1
1
C - 26
M0
0
1
0
1
Mode
Mode 0 : 13-bit counter
Mode 1 : 16-bit counter
Mode 2 : 8-bit counter with auto-reload
Mode 3 : Two 8-bit counters
EZ-USB Technical Reference Manual v1.10
Table C-3 TCON Register — SRF 0x88
Bit
Function
TCON.7
TF1 - Timer 1 overflow flag. Set to 1 when the Timer 1 count overflows; automatically
cleared when the EZ-USB vectors to the interrupt service routine.
TCON.6
TR1 - Timer 1 run control. 1 = Enable counting on Timer 1.
TCON.5
TF0 - Timer 0 overflow flag. Set to 1 when the Timer 0 count overflows; automatically
cleared when the EZ-USB vectors to the interrupt service routine.
TCON.4
TR0 - Timer 0 run control. 1 = Enable counting on Timer 0.
TCON.3
IE1 - Interrupt 1 edge detect. If external interrupt 1 is configured to be edge-sensitive
(IT1 = 1), IE1 is set when a negative edge is detected on the INT1 pin and is automatically cleared when the EZ-USB vectors to the corresponding interrupt service routine. In this case, IE1 can also be cleared by software. If external interrupt 1 is
configured to be level-sensitive (IT1 = 0), IE1 is set when the INT1 pin is 0 and automatically cleared when the INT1 pin is 1. In level-sensitive mode, software cannot
write to IE1.
TCON.2
IT1 - Interrupt 1 type select. INT1 is detected on falling edge when IT1 = 1; INT1 is
detected as a low level when IT1 = 0.
TCON.1
IE0 - Interrupt 0 edge detect. If external interrupt 0 is configured to be edge-sensitive
(IT0 = 1), IE0 is set when a negative edge is detected on the INT0 pin and is automatically cleared when the EZ-USB vectors to the corresponding interrupt service routine. In this case, IE0 can also be cleared by software. If external interrupt 0 is
configured to be level-sensitive (IT0 = 0), IE0 is set when the INT0 pin is 0 and automatically cleared when the INT0 pin is 1. In level-sensitive mode, software cannot
write to IE0.
TCON.0
IT0 - Interrupt 0 type select. INT0 is detected on falling edge when IT0 = 1; INT0 is
detected as a low level when IT0 = 0.
C.2.2.3 Mode 2, 8-Bit Counter with Auto-Reload — Timer 0 and Timer 1
In mode 2, the timer is configured as an 8-bit counter, with automatic reload of the start value on
overflow. TL0 (or TL1) is the counter, and TH0 (or TH1) stores the reload value.
As illustrated in Figure C-2, mode 2 counter control is the same as for mode 0 and mode 1. When
TL0/1 increments from 0xFF, the value stored in TH0/1 is reloaded into TL0/1.
Appendix C
C - 27
EZ-USB Technical Reference Manual
Divide by 12
CLK24
T0M (or T1M)
0
1
Divide by 4
C/ T
0
TL0 (or TL1)
0
7
RELOAD
1
CLK
T0 (or T1) pin
TR0 (or TR1)
0 TH0 (or TH1) 7
GATE
TF0 (or TF1)
INT0 (or
INT1) pin
INT
To Serial Port
(Timer 1 only)
Figure C-2. Timer 0/1 - Mode 2
C.2.2.4 Mode 3, Two 8-Bit Counters — Timer 0 Only
In mode 3, Timer 0 operates as two 8-bit counters. Selecting mode 3 for Timer 1 simply stops
Timer 1.
As shown in Figure C-3, TL0 is configured as an 8-bit counter controlled by the normal Timer 0
control bits. TL0 can either count CLK24 cycles (divided by 4 or by 12) or high-to-low transitions
on the T0 pin, as determined by the C/T Bit. The GATE function can be used to give counter
enable control to the INT0 pin.
TH0 functions as an independent 8-bit counter. However, TH0 can only count CLK24 cycles
(divided by 4 or by 12). The Timer 1 control and flag bits (TR1 and TF1) are used as the control
and flag bits for TH0.
When Timer 0 is in mode 3, Timer 1 has limited usage because Timer 0 uses the Timer 1 control
bit (TR1) and interrupt flag (TF1). Timer 1 can still be used for baud rate generation and the Timer
1 count values are still available in the TL1 and TH1 Registers.
Control of Timer 1 when Timer 0 is in mode 3 is through the Timer 1 mode bits. To turn Timer 1 on,
set Timer 1 to mode 0, 1, or 2. To turn Timer 1 off, set it to mode 3. The Timer 1 C/T Bit and T1M
Bit are still available to Timer 1. Therefore, Timer 1 can count CLK24/4, CLK24/12, or high-to-low
transitions on the T1 pin. The Timer 1 GATE function is also available when Timer 0 is in mode 3.
C - 28
EZ-USB Technical Reference Manual v1.10
Divide by 12
CLK24
T0M
0
1
Divide by 4
0
C/ T
CLK
7
TL0
0
1
T0 pin
TR0
TF0
INT
TF1
INT
GATE
INT0 pin
0
TH0
7
TR1
Figure C-3. Timer 0 - Mode 3
C.2.3 Timer Rate Control
By default, the EZ-USB timers increment every 12 CLK24 cycles, just as in the standard 8051.
Using this default rate allows existing application code with real-time dependencies, such as baud
rate, to operate properly.
Applications that require fast timing can set the timers to increment every 4 CLK24 cycles instead,
by setting bits in the Clock Control Register (CKCON) at SFR location 0x8E. (See Table C-4).
Each timer’s rate can be set independently. These settings have no effect in counter mode.
Table C-4 CKCON (SFR 0x8E) Timer Rate Control Bits
Bit
Function
CKCON.5
T2M - Timer 2 clock select. When T2M = 0, Timer 2 uses CLK24/12 (for
compatibility with standard 8051); when T2M = 1, Timer 2 uses CLK24/4.
This bit has no effect when Timer 2 is configured for baud rate generation.
CKCON.4
T1M - Timer 1 clock select. When T1M = 0, Timer 1 uses CLK24/12 (for
compatibility with standard 8051); when T1M = 1, Timer 1 uses CLK24/4.
CKCON.3
T0M - Timer 0 clock select. When T0M = 0, Timer 0 uses CLK24/12 (for
compatibility with standard 8051); when T0M = 1, Timer 0 uses CLK24/4.
Appendix C
C - 29
EZ-USB Technical Reference Manual
C.2.4 Timer 2
Timer 2 runs only in 16-bit mode and offers several capabilities not available with Timers 0 and 1.
The modes available for Timer 2 are:
•
16-bit timer/counter
•
16-bit timer with capture
•
16-bit timer/counter with auto-reload
•
Baud rate generator
The SFRs associated with Timer 2 are:
•
T2CON (SFR 0xC8) — Timer/Counter 2 Control register, (see Table C-5).
•
RCAP2L (SFR 0xCA) — Used to capture the TL2 value when Timer 2 is configured for
capture mode, or as the LSB of the 16-bit reload value when Timer 2 is configured for
auto-reload mode.
•
RCAP2H (SFR 0xCB) — Used to capture the TH2 value when Timer 2 is configured for
capture mode, or as the MSB of the 16-bit reload value when Timer 2 is configured for
auto-reload mode.
•
TL2 (SFR 0xCC) — Lower 8 bits of the 16-bit count.
•
TH2 (SFR 0xCD) — Upper 8 bits of the 16-bit count.
C - 30
EZ-USB Technical Reference Manual v1.10
Table C-5 T2CON Register — SFR 0xC8
Bit
Function
T2CON.7
TF2 - Timer 2 overflow flag. Hardware will set TF2 when the Timer 2 overflows from 0xFFFF.
TF2 must be cleared to 0 by the software. TF2 will only be set to a 1 if RCLK and TCLK are
both cleared to 0. Writing a 1 to TF2 forces a Timer 2 interrupt if enabled.
T2CON.6
EXF2 - Timer 2 external flag. Hardware will set EXF2 when a reload or capture is caused by
a high-to-low transition on the T2EX pin, and EXEN2 is set. EXF2 must be cleared to 0 by
software. Writing a 1 to EXF2 forces a Timer 2 interrupt if enabled.
T2CON.5
RCLK - Receive clock flag. Determines whether Timer 1 or Timer 2 is used for Serial Port 0
timing of received data in serial mode 1 or 3. RCLK=1 selects Timer 2 overflow as the
receive clock; RCLK=0 selects Timer 1 overflow as the receive clock.
T2CON.4
TCLK - Transmit clock flag. Determines whether Timer 1 or Timer 2 is used for Serial Port 0
timing of transmit data in serial mode 1 or 3. TCLK=1 selects Timer 2 overflow as the transmit clock; TCLK=0 selects Timer 1 overflow as the transmit clock.
T2CON.3
EXEN2 - Timer 2 external enable. EXEN2=1 enables capture or reload to occur as a result of
a high-to-low transition on the T2EX pin, if Timer 2 is not generating baud rates for the serial
port. EXEN2=0 causes Timer 2 to ignore all external events on the T2EX pin.
T2CON.2
TR2 - Timer 2 run control flag. TR2=1 starts Timer 2; TR2=0 stops Timer 2.
T2CON.1
C/T2 - Counter/Timer select. When C/T2 = 1, Timer 2 is clocked by high-to-low transitions on
the T2 pin.When C/T2 = 0 in modes 0, 1, or 2, Timer 2 is clocked by CLK24/4 or CLK24/12,
depending on the state of T2M (CKCON.5). When C/T2 = 0 in mode 3, Timer 2 is clocked by
CLK24/2, regardless of the state of CKCON.5.
T2CON.0
CP/RL2 - Capture/reload flag. When CP/RL2=1, Timer 2 captures occur on high-to-low transitions of the T2EX pin, if EXEN2 = 1. When CP/RL2 = 0, auto-reloads occur when Timer 2
overflows or when high-to-low transitions occur on the T2EX pin, if EXEN2 = 1. If either
RCLK or TCLK is set to 1, CP/RL2 will not function and Timer 2 will operate in auto-reload
mode following each overflow.
C.2.4.1 Timer 2 Mode Control
Table C-6 summarizes how the T2CON bits determine the Timer 2 mode.
Table C-6 Timer 2 Mode Control Summary
TR2
TCLK
RCLK
CP/RL2
0
X
X
X
Timer 2 stopped
Mode
1
1
X
X
Baud rate generator
1
X
1
X
Baud rate generator
1
0
0
0
16-bit timer/counter with auto-reload
1
0
0
1
16-bit timer/counter with capture
X = Don’t care
Appendix C
C - 31
EZ-USB Technical Reference Manual
C.2.5 Timer 2 — 16-Bit Timer/Counter Mode
Figure C-4 illustrates how Timer 2 operates in timer/counter mode with the optional capture feature. The C/T2 Bit determines whether the 16-bit counter counts CLK24 cycles (divided by 4 or
12), or high-to-low transitions on the T2 pin. The TR2 Bit enables the counter. When the count
increments from 0xFFFF, the TF2 flag is set and the T2OUT pin goes high for one CLK24 cycle.
C.2.5.1 Timer 2 — 16-Bit Timer/Counter Mode with Capture
The Timer 2 capture mode (Figure C-4) is the same as the 16-bit timer/counter mode, with the
addition of the capture registers and control signals.
The CP/RL2 Bit in the T2CON SFR enables the capture feature. When CP/RL2 = 1, a high-to-low
transition on the T2EX pin when EXEN2 = 1 causes the Timer 2 value to be loaded into the capture registers RCAP2L and RCAP2H.
Divide by 12
CLK24
T2M
1
Divide by 4
CP/RL2 = 1
0
0
C/ T2
CLK 0
1
7 8
15
TL2
TH2
T2 pin
78
0
EXEN2
T2EX pin
RCAP2H
RCAP2L
TR2
15
TF2
CAPTURE
EXF2
INT
Figure C-4. Timer 2 - Timer/Counter with Capture
C.2.6 Timer 2 — 16-Bit Timer/Counter Mode with Auto-Reload
When CP/RL2 = 0, Timer 2 is configured for the auto-reload mode illustrated in Figure C-5. Control
of counter input is the same as for the other 16-bit counter modes. When the count increments
from 0xFFFF, Timer 2 sets the TF2 flag and the starting value is reloaded into TL2 and TH2. Software must preload the starting value into the RCAP2L and RCAP2H registers.
When Timer 2 is in auto-reload mode, a reload can be forced by a high-to-low transition on the
T2EX pin, if enabled by EXEN2 = 1.
C - 32
EZ-USB Technical Reference Manual v1.10
Divide by 12
CLK24
1
Divide by 4
CP/RL2 = 0
T2M
0
0
C/ T2
CLK
7 8
0
TL2
1
15
TH2
T2 pin
RCAP2L
TR2
0
RCAP2H
78
15
TF2
EXEN2
EXF2
T2EX pin
INT
Figure C-5. Timer 2 - Timer/Counter with Auto Reload
C.2.7 Timer 2 — Baud Rate Generator Mode
Setting either RCLK or TCLK to 1 configures Timer 2 to generate baud rates for Serial Port 0 in
serial mode 1 or 3. Figure C-6 is the functional diagram for the Timer 2 baud rate generator mode.
In baud rate generator mode, Timer 2 functions in auto-reload mode. However, instead of setting
the TF2 flag, the counter overflow is used to generate a shift clock for the serial port function. As in
normal auto-reload mode, the overflow also causes the pre-loaded start value in the RCAP2L and
RCAP2H Registers to be reloaded into the TL2 and TH2 Registers.
When either TCLK = 1 or RCLK = 1, Timer 2 is forced into auto-reload operation, regardless of the
state of the CP/RL2 Bit. Timer 2 is used as the receive baud clock source when RCLK=1, and as
the transmit baud clock source when TCLK=1.
When operating as a baud rate generator, Timer 2 does not set the TF2 Bit. In this mode, a Timer
2 interrupt can only be generated by a high-to-low transition on the T2EX pin setting the EXF2 Bit,
and only if enabled by EXEN2 = 1.
The counter time base in baud rate generator mode is CLK24/2. To use an external clock source,
set C/T2 to 1 and apply the desired clock source to the T2 pin.
The maximum frequency for an external clock source on the T2 pin is 3 MHz.
Appendix C
C - 33
EZ-USB Technical Reference Manual
CLK24
Divide
by 2
0
TIMER 1 OVERFLOW
C/ T2
CLK
1
Divide
by 2
T2 pin
TR2
SMOD0
0
7 8
0
TL2
1
RCLK
15
TH2
0
1
RX
CLOCK
Divide
by 16
TCLK
RCAP2L
0
RCAP2H
7 8
15
1
EXEN2
0
Divide
by 16
TX
CLOCK
EXF2
T2EX pin
TIMER 2 INTERRUPT
Figure C-6. Timer 2 - Baud Rate Generator Mode
C.3 Serial Interface
The EZ-USB provides two serial ports. Serial Port 0 operates almost exactly as a standard 8051
serial port; depending on the configured mode (see Table C-7), its baud-clock source can be
CLK24/4 or CLK24/12, Timer 1, or Timer 2. Serial Port 1 is identical to Serial Port 0, except that it
cannot use Timer 2 as its baud rate generator.
Each serial port can operate in synchronous or asynchronous mode. In synchronous mode, the
EZ-USB generates the serial clock and the serial port operates in half-duplex mode. In asynchronous mode, the serial port operates in full-duplex mode. In all modes, the EZ-USB double-buffers
the incoming data so that a byte of incoming data can be received while firmware is reading the
previously-received byte.
Each serial port can operate in one of four modes, as outlined in Table C-7.
C - 34
EZ-USB Technical Reference Manual v1.10
Table C-7 Serial Port Modes
Mode
Sync /
Async
Data
Bits
Baud-Clock Source
CLK24/4 or CLK24/12
Start /
Stop
9th Bit
Function
0
Sync
8
None
None
1
Async Timer 1 (Ports 0 and 1),
Timer 2 (Port 0 only), or
8
1 start, 1 stop
None
2
Async CLK24/32 or CLK24/64
9
1 start, 1 stop 0, 1, or parity
3
Async Timer 1 (Ports 0 and 1),
Timer 2 (Port 0 only), or
9
1 start, 1 stop 0, 1, or parity
The registers associated with the serial ports are as follows. (Registers PCON and EICON also
include some functionality which is not part of the Serial Interface).
•
PCON (SFR 0x87) — Bit 7, Serial Port 0 rate control SMOD0 (Table C-11).
•
SCON0 (SFR 0x98) — Serial Port 0 control (Table C-9).
•
SBUF0 (SFR 0x99) — Serial Port 0 transmit/receive buffer.
•
EICON (SFR 0xD8) — Bit 7, Serial Port 1 rate control SMOD1 (Table C-10).
•
SCON1 (SFR 0xC0) — Serial Port 1 control (Table C-12).
•
SBUF1 (SFR 0xC1) — Serial Port 1 transmit/receive buffer.
•
T2CON (SFR 0xC8) — Baud clock source for modes 1 and 3 (RCLK and TCLK in Table C5).
C.3.1 803x/805x Compatibility
The implementation of the serial interface is similar to that of the Dallas Semiconductor,
DS80C320. Table C-8 summarizes the differences in serial interface implementation between the
Intel 8051, the Dallas Semiconductor DS80C320, and the EZ-USB.
Table C-8 Serial Interface Implementation Comparison
Feature
Intel 8051
Dallas DS80C320
EZ-USB
Number of serial ports
1
2
2
Framing error detection
not implemented
implemented
not implemented
Slave address comparison for
multiprocessor communication
not implemented
implemented
not implemented
Appendix C
C - 35
EZ-USB Technical Reference Manual
C.3.2 Mode 0
Serial mode 0 provides synchronous, half-duplex serial communication. For Serial Port 0, serial
data output occurs on the RXD0OUT pin, serial data is received on the RXD0 pin, and the TXD0
pin provides the shift clock for both transmit and receive. For Serial Port 1, the corresponding pins
are RXD1OUT, RXD1, and TXD1.
The serial mode 0 baud rate is either CLK24/12 or CLK24/4, depending on the state of the SM2_0
bit (or SM2_1 for Serial Port 1). When SM2_0 = 0, the baud rate is CLK24/12, when SM2_0 = 1,
the baud rate is CLK24/4.
Mode 0 operation is identical to the standard 8051. Data transmission begins when an instruction
writes to the SBUF0 (or SBUF1) SFR. The USART shifts the data, LSB first, at the selected baud
rate, until the 8-bit value has been shifted out.
Mode 0 data reception begins when the REN_0 (or REN_1) bit is set and the RI_0 (or RI_1) bit is
cleared in the corresponding SCON SFR. The shift clock is activated and the USART shifts data,
LSB first, in on each rising edge of the shift clock until 8 bits have been received. One CLK24
cycle after the 8th bit is shifted in, the RI_0 (or RI_1) bit is set and reception stops until the software clears the RI bit.
Figure C-7 through Figure C-10 illustrate Serial Port Mode 0 transmit and receive timing for both
low-speed (CLK24/12) and high-speed (CLK24/4) operation. The figures show Port 0 signal
names, RXD0, RXD0OUT, and TXD0. The timing is the same for Port 1 signals RXD1, RXD1OUT,
and TXD1, respectively.
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EZ-USB Technical Reference Manual v1.10
Table C-9 SCON0 Register — SFR 98h
Bit
Function
SCON0.7
SM0_0 - Serial Port 0 mode bit 0.
SCON0.6
SM1_0 - Serial Port 0 mode bit 1, decoded as:
SM0_0 SM1_0 Mode
SCON0.5
0
0
0
0
1
1
1
0
2
1
1
3
SM2_0 - Multiprocessor communication enable. In modes 2 and 3, this bit enables the multiprocessor communication feature. If SM2_0 = 1 in mode 2 or 3, then RI_0 will not be activated if the received 9th bit is 0.
If SM2_0=1 in mode 1, then RI_0 will only be activated if a valid stop is received. In mode
0, SM2_0 establishes the baud rate: when SM2_0=0, the baud rate is CLK24/12; when
SM2_0=1, the baud rate is CLK24/4.
SCON0.4
REN_0 - Receive enable. When REN_0=1, reception is enabled.
SCON0.3
TB8_0 - Defines the state of the 9th data bit transmitted in modes 2 and 3.
SCON0.2
RB8_0 - In modes 2 and 3, RB8_0 indicates the state of the 9th bit received. In mode 1,
RB8_0 indicates the state of the received stop bit. In mode 0, RB8_0 is not used.
SCON0.1
TI_0 - Transmit interrupt flag. Indicates that the transmit data word has been shifted out. In
mode 0, TI_0 is set at the end of the 8th data bit. In all other modes, TI_0 is set when the
stop bit is placed on the TXD0 pin. TI_0 must be cleared by firmware.
SCON0.0
RI_0 - Receive interrupt flag. Indicates that serial data word has been received. In mode 0,
RI_0 is set at the end of the 8th data bit. In mode 1, RI_0 is set after the last sample of the
incoming stop bit, subject to the state of SM2_0. In modes 2 and 3, RI_0 is set at the end of
the last sample of RB8_0. RI_0 must be cleared by firmware.
Table C-10 EICON (SFR 0xD8) SMOD1 Bit
Bit
Function
EICON.7
SMOD1 - Serial Port 1 baud rate doubler enable. When SMOD1 = 1 the baud rate for Serial
Port is doubled.
Table C-11 PCON (SFR 0x87) SMOD0 Bit
Bit
Function
PCON.7
SMOD0 - Serial Port 0 baud rate double enable. When SMOD0 = 1, the baud rate for Serial
Port 0 is doubled.
Appendix C
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EZ-USB Technical Reference Manual
Table C-12 SCON1 Register — SFR C0h
Bit
Function
SCON1.7
SM0_1 - Serial Port 1 mode bit 0.
SCON1.6
SM1_1 - Serial Port 1 mode bit 1, decoded as:
SM0_1 SM1_1 Mode
SCON1.5
0
0
0
0
1
1
1
0
2
1
1
3
SM2_1 - Multiprocessor communication enable. In modes 2 and 3, this bit enables the
multiprocessor communication feature. If SM2_1 = 1 in mode 2 or 3, then RI_1 will not be
activated if the received 9th bit is 0.
If SM2_1=1 in mode 1, then RI_1 will only be activated if a valid stop is received. In mode
0, SM2_1 establishes the baud rate: when SM2_1=0, the baud rate is CLK24/12; when
SM2_1=1, the baud rate is CLK24/4.
SCON1.4
REN_1 - Receive enable. When REN_1=1, reception is enabled.
SCON1.3
TB8_1 - Defines the state of the 9th data bit transmitted in modes 2 and 3.
SCON1.2
RB8_1 - In modes 2 and 3, RB8_1 indicates the state of the 9th bit received. In mode 1,
RB8_1 indicates the state of the received stop bit. In mode 0, RB8_1 is not used.
SCON1.1
TI_1 - Transmit interrupt flag. Indicates that the transmit data word has been shifted out. In
mode 0, TI_1 is set at the end of the 8th data bit. In all other modes, TI_1 is set when the
stop bit is placed on the TXD1 pin. TI_1 must be cleared by the software.
SCON1.0
RI_1 - Receive interrupt flag. Indicates that serial data word has been received. In mode 0,
RI_1 is set at the end of the 8th data bit. In mode 1, RI_1 is set after the last sample of the
incoming stop bit, subject to the state of SM2_1. In modes 2 and 3, RI_1 is set at the end
of the last sample of RB8_1. RI_1 must be cleared by the software.
C - 38
EZ-USB Technical Reference Manual v1.10
CLK24
D0
RXD0
D1
D2
D3
D4
D5
D6
D7
RXD0OUT
TXD0
TI
RI
Figure C-7. Serial Port Mode 0 Receive Timing - Low Speed Operation
CLK24
RXD0
D0
D1
D2
D3
D4
D5
D6
D7
RXD0OUT
TXD0
TI
RI
Figure C-8. Serial Port Mode 0 Receive Timing - High Speed Operation
At both low and high speed in Mode 0, data on RXD0 is sampled two CLK24 cycles before the rising clock edge on TXD0.
Appendix C
C - 39
EZ-USB Technical Reference Manual
CLK24
RXD0
RXD0OUT
D0
D1
D2
D3
D4
D5
D6
D7
TXD0
TI
RI
Figure C-9. Serial Port Mode 0 Transmit Timing - Low Speed Operation
CLK24
RXD0
RXD0OUT
D0
D1
D2
D3
D4
D5
D6
D7
TXD0
TI
RI
Figure C-10. Serial Port Mode 0 Transmit Timing - High Speed Operation
C.3.3 Mode 1
Mode 1 provides standard asynchronous, full-duplex communication, using a total of 10 bits: 1
start bit, 8 data bits, and 1 stop bit. For receive operations, the stop bit is stored in RB8_0 (or
RB8_1). Data bits are received and transmitted LSB first.
Mode 1 operation is identical to that of the standard 8051 when Timer 1 uses CLK24/12, (T1M=0,
the default).
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EZ-USB Technical Reference Manual v1.10
C.3.3.1 Mode 1 Baud Rate
The mode 1 baud rate is a function of timer overflow. Serial Port 0 can use either Timer 1 or Timer
2 to generate baud rates. Serial Port 1 can only use Timer 1. The two serial ports can run at the
same baud rate if they both use Timer 1, or different baud rates if Serial Port 0 uses Timer 2 and
Serial Port 1 uses Timer 1.
Each time the timer increments from its maximum count (0xFF for Timer 1 or 0xFFFF for Timer 2),
a clock is sent to the baud rate circuit. That clock is then divided by 16 to generate the baud rate.
When using Timer 1, the SMOD0 (or SMOD1) Bit selects whether or not to divide the Timer 1 rollover rate by 2. Therefore, when using Timer 1, the baud rate is determined by the equation:
SMODx
2
Baud Rate =
× Timer 1 Overflow
32
When using Timer 2, the baud rate is determined by the equation:
Baud Rate =
Timer 2 Overflow
16
To use Timer 1 as the baud rate generator, it is generally best to use Timer 1 mode 2 (8-bit counter
with auto-reload), although any counter mode can be used. In mode 2, the Timer 1 reload value is
stored in the TH1 register, which makes the complete formula for Timer 1:
Baud Rate =
2
SMODx
×
32
CLK24
(12 - 8 × T1M) × (256 - TH1)
To derive the required TH1 value from a known baud rate when T1M=0, use the equation:
TH1 =
256 -
2
SMODx
× CLK24
384 × Baud Rate
To derive the required TH1 value from a known baud rate when T1M=1, use the equation:
TH1 =
256 -
SMODx
2
x CLK24
128 x Baud Rate
Appendix C
C - 41
EZ-USB Technical Reference Manual
Very low serial port baud rates may be achieved with Timer 1 by enabling the Timer 1 interrupt,
configuring Timer 1 to mode 1, and using the Timer 1 interrupt to initiate a 16-bit software reload.
Table C-13 lists sample reload values for a variety of common serial port baud rates, using Timer 1
operating in mode 2 (TMOD.5:4=10) with a CLK24/4 clock source (T1M=1) and the full timer rollover (SMOD1=1).
Table C-13 Timer 1 Reload Values for Common Serial Port Mode 1 Baud Rates
Nominal
Rate
TH1
Reload
Value
Actual
Rate
Error
57600
F9
53571
-6.99%
38400
F6
37500
-2.34%
28800
F3
28846
+0.16%
19200
EC
18750
-2.34%
9600
D9
9615
+0.16%
4800
B2
4807
+0.16%
2400
64
2403
+0.16%
Settings: SMOD=1, C/T=0, Timer1 Mode=2, T1M=1
Note: Using rates that are off by 2% or more will not work in all systems.
More accurate baud rates may be achieved by using Timer 2 as the baud rate generator. To use
Timer 2 as the baud rate generator, configure Timer 2 in auto-reload mode and set the TCLK and/
or RCLK bits in the T2CON SFR. TCLK selects Timer 2 as the baud rate generator for the transmitter; RCLK selects Timer 2 as the baud rate generator for the receiver. The 16-bit reload value
for Timer 2 is stored in the RCAP2L and RCA2H SFRs, which makes the equation for the Timer 2
baud rate:
CLK24
Baud Rate =
32 × (65536 - 256×RCAP2H + RCAP2L)
To derive the required RCAP2H and RCAP2L values from a known baud rate, use the equation:
RCAP2H:L =
65536 -
CLK24
32 × Baud Rate
When either RCLK or TCLK is set, the TF2 flag is not set on a Timer 2 rollover and the T2EX
reload trigger is disabled.
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EZ-USB Technical Reference Manual v1.10
Table C-14 lists sample RCAP2H:L reload values for a variety of common serial baud rates.
Table C-14 Timer 2 Reload Values for Common Serial Port Mode 1 Baud Rates
RCAP2H:L
Reload
Value
Actual
Rate
57600
FFF3
57692
+0.16%
38400
FFEC
37500
-2.34%
28800
FFE6
28846
+0.16%
19200
FFD9
19230
+0.16%
9600
FFB2
9615
+0.16%
4800
FF64
4807
+0.16%
2400
FEC8
2403
+0.16%
Nominal Rate
Error
Note: using rates that are off by 2.3% or more will not work in all systems.
C.3.3.2 Mode 1 Transmit
Figure C-11 illustrates the mode 1 transmit timing. In mode 1, the USART begins transmitting after
the first rollover of the divide-by-16 counter after the software writes to the SBUF0 (or SBUF1) register. The USART transmits data on the TXD0 (or TXD1) pin in the following order: start bit, 8 data
bits (LSB first), stop bit. The TI_0 (or TI_1) bit is set 2 CLK24 cycles after the stop bit is transmitted.
C.3.4 Mode 1 Receive
Figure C-12 illustrates the mode 1 receive timing. Reception begins at the falling edge of a start bit
received on the RXD0 (or RXD1) pin, when enabled by the REN_0 (or REN_1) Bit. For this purpose, the RXD0 (or RXD1) pin is sampled 16 times per bit for any baud rate. When a falling edge
of a start bit is detected, the divide-by-16 counter used to generate the receive clock is reset to
align the counter rollover to the bit boundaries.
For noise rejection, the serial port establishes the content of each received bit by a majority decision of 3 consecutive samples in the middle of each bit time. For the start bit, if the falling edge on
the RXD0 (or RXD1) pin is not verified by a majority decision of 3 consecutive samples (low), then
the serial port stops reception and waits for another falling edge on the RXD0 (or RXD1) pin.
At the middle of the stop bit time, the serial port checks for the following conditions:
•
RI_0 (or RI_1) = 0
•
If SM2_0 (or SM2_1) = 1, the state of the stop bit is 1
(If SM2_0 (or SM2_1) = 0, the state of the stop bit doesn’t matter.
Appendix C
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EZ-USB Technical Reference Manual
If the above conditions are met, the serial port then writes the received byte to the SBUF0 (or
SBUF1) Register, loads the stop bit into RB8_0 (or RB8_1), and sets the RI_0 (or RI_1) Bit. If the
above conditions are not met, the received data is lost, the SBUF Register and RB8 Bit are not
loaded, and the RI Bit is not set.
After the middle of the stop bit time, the serial port waits for another high-to-low transition on the
(RXD0 or RXD1) pin.
Write to
SBUF0
TX CLK
SHIFT
TXD0
START
D0
D1
D2
D3
D4
D5
D6
D7
STOP
RXD0
RXD0OUT
TI_0
RI_0
Figure C-11. Serial Port 0 Mode 1 Transmit Timing
RX CLK
RXD0
START D0
D1
D2
D3
D4
D5
D6
D7
STOP
Bit detector
sampling
SHIFT
RXD0OUT
TXD0
TI_0
RI_0
Figure C-12. Serial Port 0 Mode 1 Receive Timing
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EZ-USB Technical Reference Manual v1.10
C.3.5 Mode 2
Mode 2 provides asynchronous, full-duplex communication, using a total of 11 bits: 1 start bit, 8
data bits, a programmable 9th bit, and 1 stop bit. The data bits are transmitted and received LSB
first. For transmission, the 9th bit is determined by the value in TB8_0 (or TB8_1). To use the 9th
bit as a parity bit, move the value of the P bit (SFR PSW.0) to TB8_0 (or TB8_1).
The Mode 2 baud rate is either CLK24/32 or CLK24/64, as determined by the SMOD0 (or SMOD1)
bit. The formula for the mode 2 baud rate is:
Baud Rate =
2
SMODx
× CLK24
64
Mode 2 operation is identical to the standard 8051.
C.3.5.1 Mode 2 Transmit
Figure C-13 illustrates the mode 2 transmit timing. Transmission begins after the first rollover of
the divide-by-16 counter following a software write to SBUF0 (or SBUF1). The USART shifts data
out on the TXD0 (or TXD1) pin in the following order: start bit, data bits (LSB first), 9th bit, stop bit.
The TI_0 (or TI_1) Bit is set when the stop bit is placed on the TXD0 (or TXD1) pin.
C.3.5.2 Mode 2 Receive
Figure C-14 illustrates the mode 2 receive timing. Reception begins at the falling edge of a start bit
received on the RXD0 (or RXD1) pin, when enabled by the REN_0 (or REN_1) Bit. For this purpose, the RXD0 (or RXD1) pin is sampled 16 times per bit for any baud rate. When a falling edge
of a start bit is detected, the divide-by-16 counter used to generate the receive clock is reset to
align the counter rollover to the bit boundaries.
For noise rejection, the serial port establishes the content of each received bit by a majority decision of 3 consecutive samples in the middle of each bit time. For the start bit, if the falling edge on
the RXD0 (or RXD1) pin is not verified by a majority decision of 3 consecutive samples (low), then
the serial port stops reception and waits for another falling edge on the RXD0 (or RXD1) pin.
At the middle of the stop bit time, the serial port checks for the following conditions:
•
RI_0 (or RI_1) = 0
•
If SM2_0 (or SM2_1) = 1, the state of the stop bit is 1.
(If SM2_0 (or SM2_1) = 0, the state of the stop bit doesn’t matter.)
If the above conditions are met, the serial port then writes the received byte to the SBUF0 (or
SBUF1) Register, loads the stop bit into RB8_0 (or RB8_1), and sets the RI_0 (or RI_1) Bit. If the
above conditions are not met, the received data is lost, the SBUF Register and RB8 Bit are not
Appendix C
C - 45
EZ-USB Technical Reference Manual
loaded, and the RI Bit is not set. After the middle of the stop bit time, the serial port waits for
another high-to-low transition on the RXD0 (or RXD1) pin.
Write to
SBUF0
TX CLK
SHIFT
TXD0
START D0
D1
D2
D3
D4
D5
D6
D7
TB8
STOP
RB8
STOP
RXD0
RXD0OUT
TI_0
RI_0
Figure C-13. Serial Port 0 Mode 2 Transmit Timing
RX CLK
RXD0
START D0
D1
D2
D3
D4
D5
D6
D7
Bit detector
sampling
SHIFT
RXD0OUT
TXD0
TI_0
RI_0
Figure C-14. Serial Port 0 Mode 2 Receive Timing
C.3.6 Mode 3
Mode 3 provides asynchronous, full-duplex communication, using a total of 11 bits: 1 start bit, 8
data bits, a programmable 9th bit, and 1 stop bit. The data bits are transmitted and received LSB
first.
C - 46
EZ-USB Technical Reference Manual v1.10
The mode 3 transmit and operations are identical to mode 2. The mode 3 baud rate generation is
identical to mode 1. That is, mode 3 is a combination of mode 2 protocol and mode 1 baud rate.
Figure C-15 illustrates the mode 3 transmit timing. Figure C-16 illustrates the mode 3 receive timing.
Mode 3 operation is identical to that of the standard 8051 when Timer 1 uses CLK24/12, (T1M=0,
the default).
Write to
SBUF0
TX CLK
SHIFT
TXD0
START D0
D1
D2
D3
D4
D5
D6
D7
TB8
STOP
RXD0
RXD0OUT
TI_0
RI_0
Figure C-15. Serial Port 0 Mode 3 Transmit Timing
RX CLK
RXD0
START
D0
D1
D2
D3
D4
D5
D6
D7
RB8 STOP
Bit detector
sampling
SHIFT
RXD0OUT
TXD0
TI_0
RI_0
Figure C-16. Serial Port 0 Mode 3 Receive Timing
Appendix C
C - 47
EZ-USB Technical Reference Manual
C.4 Interrupts
The EZ-USB’s interrupt architecture is an enhanced and expanded version of the standard 8051’s.
The EZ-USB responds to the interrupts shown in Table C-15; interrupt sources that are not
present in the standard 8051 are shown in bold type.
.
Table C-15 EZ-USB Interrupts
EZ-USB
Interrupt
Source
Interrupt
Vector
Natural
Priority
IE0
INT0 Pin
0x0003
1
TF0
Timer 0 Overflow
0x000B
2
IE1
INT1 Pin
0x0013
3
TF1
Timer 1 Overflow
0x001B
4
RI_0 & TI_0
USART0 Rx & Tx
0x0023
5
TF2
Timer 2 Overflow
0x002B
6
Resume
WAKEUP or USB Resume
0x0033
0
(Highest
Priority)
RI_1 & TI_1
USART1 Rx & Tx
0x003B
7
USBINT
USB
0x0043
8
I²CINT
I²C Bus
0x004B
9
IE4
INT4 Pin
0x0053
10
IE5
INT5 Pin
0x005B
11
IE6
INT6 Pin
0x0063
12
The Natural Priority column in Table C-15 shows the EZ-USB interrupt priorities. The EZ-USB
can assign each interrupt to a high or low priority group; priorities within the groups are resolved
using the natural priorities.
C.5 Interrupt-Control SFRs
The following SFRs are associated with interrupt control:
•
IE - SFR 0xA8 (Table C-16)
•
IP - SFR 0xB8 (Table C-17)
•
EXIF - SFR 0x91 (Table C-18)
C - 48
EZ-USB Technical Reference Manual v1.10
•
EICON - SFR 0xD8 (Table C-19)
•
EIE - SFR 0xE8 (Table C-20)
•
EIP - SFR 0xF8 (Table C-21)
The IE and IP SFRs provide interrupt enable and priority control for the standard interrupt unit, as
with the standard 8051. Additionally, these SFRs provide control bits for the Serial Port 1 interrupt.
The EXIF, EICON, EIE and EIP Registers provide flags, enable control, and priority control.
Table C-16 IE Register — SFR 0xA8
Bit
Function
IE.7
EA - Global interrupt enable. Controls masking of all interrupts except USB wakeup
(resume). EA = 0 disables all interrupts except USB wakeup. When EA = 1, interrupts are
enabled or masked by their individual enable bits.
IE.6
ES1 - Enable Serial Port 1 interrupt. ES1 = 0 disables Serial port 1 interrupts (TI_1 and
RI_1). ES1 = 1 enables interrupts generated by the TI_1 or RI_1 flag.
IE.5
ET2 - Enable Timer 2 interrupt. ET2 = 0 disables Timer 2 interrupt (TF2). ET2=1 enables
interrupts generated by the TF2 or EXF2 flag.
IE.4
ES0 - Enable Serial Port 0 interrupt. ES0 = 0 disables Serial Port 0 interrupts (TI_0 and
RI_0). ES0=1 enables interrupts generated by the TI_0 or RI_0 flag.
IE.3
ET1 - Enable Timer 1 interrupt. ET1 = 0 disables Timer 1 interrupt (TF1). ET1=1 enables
interrupts generated by the TF1 flag.
IE.2
EX1 - Enable external interrupt 1. EX1 = 0 disables external interrupt 1 (INT1). EX1=1
enables interrupts generated by the INT1 pin.
IE.1
ET0 - Enable Timer 0 interrupt. ET0 = 0 disables Timer 0 interrupt (TF0). ET0=1 enables
interrupts generated by the TF0 flag.
IE.0
EX0 - Enable external interrupt 0. EX0 = 0 disables external interrupt 0 (INT0). EX0=1
enables interrupts generated by the INT0 pin.
Appendix C
C - 49
EZ-USB Technical Reference Manual
Table C-17 IP Register — SFR 0xB8
Bit
Function
IP.7
Reserved. Read as 1.
IP.6
PS1 - Serial Port 1 interrupt priority control. PS1 = 0 sets Serial Port 1 interrupt
(TI_1 or RI_1) to low priority. PS1 = 1 sets Serial port 1 interrupt to high priority.
IP.5
PT2 - Timer 2 interrupt priority control. PT2 = 0 sets Timer 2 interrupt (TF2) to low
priority. PT2 = 1 sets Timer 2 interrupt to high priority.
IP.4
PS0 - Serial Port 0 interrupt priority control. PS0 = 0 sets Serial Port 0 interrupt
(TI_0 or RI_0) to low priority. PS0 = 1 sets Serial Port 0 interrupt to high priority.
IP.3
PT1 - Timer 1 interrupt priority control. PT1 = 0 sets Timer 1 interrupt (TF1) to low
priority. PT1 = 1 sets Timer 1 interrupt to high priority.
IP.2
PX1 - External interrupt 1 priority control. PX1 = 0 sets external interrupt 1 (INT1)
to low priority. PT1 = 1 sets external interrupt 1 to high priority.
IP.1
PT0 - Timer 0 interrupt priority control. PT0 = 0 sets Timer 0 interrupt (TF0) to low
priority. PT0 = 1 sets Timer 0 interrupt to high priority.
IP.0
PX0 - External interrupt 0 priority control. PX0 = 0 sets external interrupt 0 (INT0)
to low priority. PX0 = 1 sets external interrupt 0 to high priority.
Table C-18 EXIF Register — SFR 0x91
C - 50
Bit
Function
EXIF.7
IE5 - External Interrupt 5 flag. IE5 = 1 indicates a falling edge was detected at the
INT5 pin. IE5 must be cleared by software. Setting IE5 in software generates an
interrupt, if enabled.
EXIF.6
IE4 - External Interrupt 4 flag. The “INT4” interrupt indicates that a rising edge
was detected at the INT4 pin. IE4 must be cleared by software. Setting IE4 in
software generates an interrupt, if enabled.
EXIF.5
I2CINT - I²C Bus Interrupt flag. I2CINT = 1 indicates an I²C Bus interrupt. I2CINT
must be cleared by software. Setting I2CINT in software generates an interrupt, if
enabled.
EXIF.4
USBINT - USB Interrupt flag. USBINT = 1 indicates an USB interrupt. USBINT
must be cleared by software. Setting USBINT in software generates an interrupt,
if enabled.
EXIF.3
Reserved. Read as 1.
EXIF.2-0
Reserved. Read as 0.
EZ-USB Technical Reference Manual v1.10
Table C-19 EICON Register — SFR 0xD8
Bit
Function
EICON.7
SMOD1 - Serial Port 1 baud rate doubler enable. When SMOD1 = 1, the
baud rate for Serial Port 1 is doubled.
EICON.6
Reserved. Read as 1.
EICON.5
ERESI - Enable Resume interrupt. ERESI = 0 disables the Resume interrupt. ERESI = 1 enables interrupts generated by the resume event.
EICON.4
RESI - Wakeup interrupt flag. RESI = 1 indicates a false-to-true transition
was detected at the WAKEUP pin, or that USB activity has resumed from
the suspended state. RESI must be cleared by software before exiting the
interrupt service routine, otherwise the interrupt will immediately be reasserted. Setting RESI = 1 in software generates a wakeup interrupt, if
enabled.
EICON.3
INT6 - External interrupt 6. When INT6 = 1, the INT6 pin has detected a low
to high transition. INT6 must be cleared by software. Setting this bit in software generates an INT6 interrupt, if enabled.
EICON.2-0
Reserved. Read as 0.
Table C-20 EIE Register — SFR 0xE8
Bit
EIE.7-5
Appendix C
Function
Reserved. Read as 1.
EIE.4
EX6 - Enable external interrupt 6. EX6 = 0 disables external interrupt 6
(INT6). EX6 = 1 enables interrupts generated by the INT6 pin.
EIE.3
EX5 - Enable external interrupt 5. EX5 = 0 disables external interrupt 5
(INT5). EX5 = 1 enables interrupts generated by the INT5 pin.
EIE.2
EX4 - Enable external interrupt 4. EX4 = 0 disables external interrupt 4
(INT4). EX4 = 1 enables interrupts generated by the INT4 pin.
EIE.1
EI2C - Enable I²C Bus interrupt (I2CINT). EI2C = 0 disables the I² C Bus
interrupt. EI2C = 1 enables interrupts generated by the I ²C Bus controller.
EIE.0
EUSB - Enable USB interrupt (USBINT). EUSB = 0 disables USB interrupts.
EUSB = 1 enables interrupts generated by the USB Interface.
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EZ-USB Technical Reference Manual
Table C-21 EIP Register — SFR 0xF8
Bit
EIP.7-5
Function
Reserved. Read as 1.
EIP.4
PX6 - External interrupt 6 priority control. PX6 = 0 sets external interrupt 6 (INT6)
to low priority. PX6 = 1 sets external interrupt 6 to high priority.
EIP.3
PX5 - External interrupt 5 priority control. PX5 = 0 sets external interrupt 5 (INT5)
to low priority. PX5=1 sets external interrupt 5 to high priority.
EIP.2
PX4 - External interrupt 4 priority control. PX4 = 0 sets external interrupt 4
(INT4) to low priority. PX4=1 sets external interrupt 4 to high priority.
EIP.1
PI2C - I2CINT priority control. PI2C = 0 sets I² C Bus interrupt to low priority.
PI2C=1 sets I² C Bus interrupt to high priority.
EIP.0
PUSB - USBINT priority control. PUSB = 0 sets USB interrupt to low priority.
PUSB=1 sets USB interrupt to high priority.
C.5.1 803x/805x Compatibility
The implementation of interrupts is similar to that of the Dallas Semiconductor DS80C320. Table
C-22 summarizes the differences in interrupt implementation between the Intel 8051, the Dallas
Semiconductor DS80C320, and the EZ-USB.
Table C-22 Summary of Interrupt Compatibility
Feature
Power Fail Interrupt
Intel
8051
Dallas
DS80C320
Cypress
EZ-USB
Not implemented Internally generated Replaced with RESUME Interrupt
External Interrupt 0
Implemented
Implemented
Implemented
Timer 0 Interrupt
Implemented
Implemented
Implemented
External Interrupt 1
Implemented
Implemented
Implemented
Timer 1 Interrupt
Implemented
Implemented
Implemented
Serial Port 0 Interrupt
Implemented
Implemented
Implemented
Timer 2 Interrupt
Not implemented Implemented
Implemented
Serial Port 1 Interrupt
Not implemented Implemented
Implemented
External Interrupt 2
Not implemented Implemented
Replaced with autovectored USB Interrupt
External Interrupt 3
Not implemented Implemented
Replaced with I²C Bus Interrupt
External Interrupt 4
Not implemented Implemented
Implemented
External Interrupt 5
Not implemented Implemented
Implemented
Watchdog Timer Interrupt Not implemented Internally generated Replaced with External Interrupt 6
Real-time Clock Interrupt Not implemented Implemented
C - 52
Not implemented
EZ-USB Technical Reference Manual v1.10
C.6 Interrupt Processing
When an enabled interrupt occurs, the EZ-USB completes the instruction it’s currently executing,
then vectors to the address of the interrupt service routine (ISR) associated with that interrupt (see
Table C-23). The EZ-USB executes the ISR to completion unless another interrupt of higher priority occurs. Each ISR ends with a RETI (return from interrupt) instruction. After executing the RETI,
the EZ-USB continues executing firmware at the instruction following the one which was executing
when the interrupt occurred.
The EZ-USB always completes the instruction in progress before servicing an interrupt. If the
instruction in progress is RETI, or a write access to any of the IP, IE, EIP, or EIE SFRs, the EZUSB completes one additional instruction before servicing the interrupt.
C.6.1 Interrupt Masking
The EA Bit in the IE SFR (IE.7) is a global enable for all interrupts except the RESUME (USB
wakeup) interrupt, which is always enabled. When EA = 1, each interrupt is enabled or masked by
its individual enable bit. When EA = 0, all interrupts are masked except the USB wakeup interrupt.
Table C-23 provides a summary of interrupt sources, flags, enables, and priorities.
Appendix C
C - 53
EZ-USB Technical Reference Manual
Table C-23 Interrupt Flags, Enables, Priority Control, and Vectors
Interrupt
Description
Interrupt
Request Flag
Interrupt
Enable
Assigned
Natural Interrupt
Priority
Priority Vector
Control
RESUME
Resume interrupt
EICON.4
EICON.5 Always
Highest
0
(highest)
0x0033
INT0
External interrupt 0
TCON.1
IE.0
IP.0
1
0x0003
TF0
Timer 0 interrupt
TCON.5
IE.1
INT1
External interrupt 1
TCON.3
IE.2
IP.1
2
0x000B
IP.2
3
0x0013
TF1
Timer 1 interrupt
TCON.7
IE.3
IP.3
4
0x001B
TI_0 or RI_0 Serial port 0 transmit or
receive interrupt
SCON0.1 (TI.0)
SCON0.0 (RI_0)
IE.4
IP.4
5
0x0023
TF2 or EXF2 Timer 2 interrupt
T2CON.7 (TF2) IE.5
T2CON.6 (EXF2)
IP.5
6
0x002B
TI_1 or RI_1 Serial port 1 transmit or
receive interrupt
SCON1.1 (TI_1)
SCON1.0 (RI_1)
IE.6
IP.6
7
0x003B
USBINT
Autovectored USB interrupt
EXIF.4
EIE.0
EIP.0
8
0x0043
I2C IN T
I² C Bus interrupt
EXIF.5
EIE.1
EIP.1
9
0x004B
INT4
External interrupt 4
EXIF.6
EIE.2
EIP.2
10
0x0053
INT5
External interrupt 5
EXIF.7
EIE.3
EIP.3
11
0x005B
INT6
External interrupt 6
EICON.3
EIE.4
EIP.4
12
0x0063
C.6.1.1 Interrupt Priorities
There are two stages of interrupt priority: assigned interrupt level and natural priority. Assigned priority is set by EZ-USB firmware; natural priority is as shown in Table C-23, and is fixed.
The assigned interrupt level (highest, high, or low) takes precedence over natural priority. The
RESUME (USB wakeup) interrupt always has highest assigned priority and is the only interrupt
that can have highest assigned priority. All other interrupts can be assigned either high or low priority.
In addition to an assigned priority level (high or low), each interrupt also has a natural priority, as
listed in Table C-23. Simultaneous interrupts with the same assigned priority level (for example,
both high) are resolved according to their natural priority. For example, if INT0 and INT1 are both
assigned high priority and both occur simultaneously, INT0 takes precedence due to its higher natural priority.
Once an interrupt is being serviced, only an interrupt of higher assigned priority level can interrupt
the service routine. That is, an ISR for a low-assigned-level interrupt can only be interrupted by a
high-assigned-level interrupt. An ISR for a high-assigned-level interrupt can only be interrupted by
the RESUME interrupt.
C - 54
EZ-USB Technical Reference Manual v1.10
C.6.2 Interrupt Sampling
The internal timers and serial ports generate interrupts by setting the interrupt flag bits shown in
Table C-23. These interrupts are sampled once per instruction cycle (i.e., once every 4 CLK24
cycles).
INT0 and INT1 are both active low and can be programmed to be either edge-sensitive or levelsensitive, through the IT0 and IT1 bits in the TCON SFR. When ITx = 0, INTx is level-sensitive and
the EZ-USB sets the IEx flag when the INTx pin is sampled low. When ITx = 1, INTx is edge-sensitive and the EZ-USB sets the IEx flag when the INTx pin is sampled high then low on consecutive
samples.
The remaining five interrupts (INT 4-6, USB & I ² C Bus interrupts) are edge-sensitive only. INT6
and INT4 are active high and INT5 is active low.
To ensure that edge-sensitive interrupts are detected, the interrupt pins should be held in each
state for a minimum of one instruction cycle (4 CLK24 cycles). Level-sensitive interrupts are not
latched; their pins must remain asserted until the interrupt is serviced.
C.6.3 Interrupt Latency
Interrupt response time depends on the current state of the EZ-USB. The fastest response time is
5 instruction cycles: 1 to detect the interrupt, and 4 to perform the LCALL to the ISR.
The maximum latency is 13 instruction cycles. This 13-cycle latency occurs when the EZ-USB is
currently executing a RETI instruction followed by a MUL or DIV instruction. The 13 instruction
cycles in this case are: 1 to detect the interrupt, 3 to complete the RETI, 5 to execute the DIV or
MUL, and 4 to execute the LCALL to the ISR.
This13-instruction-cycle latency excludes autovector latency for the USB interrupts (see Section
9.10). Autovectoring adds a fixed 4 instruction cycles, so the maximum latency for an autovectored
USB interrupt is 13 + 4 = 17 instruction cycles.
Appendix C
C - 55
EZ-USB Technical Reference Manual
C - 56
EZ-USB Technical Reference Manual v1.10
Appendix D
AN21xx Register Summary
The following table is a summary of all the EZ-USB Registers.
In the “b7-b0” columns, bit positions that contain a 0 or a 1 cannot be written to and, when read,
always return the value shown (0 or 1). Bit positions that contain “-” are available but unused.
The “Default” column shows each register’s power-on-reset value (“x” indicates “undefined”).
The “Access” column indicates each register’s read/write accessibility.
Appendix D
D - 57
EZ-USB Technical Reference Manual
D - 58
EZ-USB Technical Reference Manual v1.10
EZ-USB Registers & Buffers
Register Summary
Addr
7B40
7B80
7BC0
7C00
7C40
7C80
7CC0
7D00
7D40
7D80
7DC0
7E00
7E40
7E80
7EC0
7F00
7F60
7F61
7F62
7F63
7F64
7F65
7F66
7F67
7F68
7F69
7F6A
7F6B
7F6C
7F6D
7F6E
7F6F
7F70
7F71
7F72
7F73
Name
Description
Endpoint 0-7 Data Buffers
OUT7BUF
(64 bytes)
IN7BUF
(64 bytes)
OUT6BUF
(64 bytes)
IN6BUF
(64 bytes)
OUT5BUF
(64 bytes)
IN5BUF
(64 bytes)
OUT4BUF
(64 bytes)
IN4BUF
(64 bytes)
OUT3BUF
(64 bytes)
IN3BUF
(64 bytes)
OUT2BUF
(64 bytes)
IN2BUF
(64 bytes)
OUT1BUF
(64 bytes)
IN1BUF
(64 bytes)
OUT0BUF
(64 bytes)
IN0BUF
(64 bytes)
7F40-7F5F(reserved)
Isochronous Data
OUT8DATA
Endpoint 8 OUT Data
OUT9DATA
Endpoint 9 OUT Data
OUT10DATA
Endpoint 10 OUT Data
OUT11DATA
Endpoint 11 OUT Data
OUT12DATA
Endpoint 12 OUT Data
OUT13DATA
Endpoint 13 OUT Data
OUT14DATA
Endpoint 14 OUT Data
OUT15DATA
Endpoint 15 OUT Data
IN8DATA
Endpoint 8 IN Data
IN9DATA
Endpoint 9 IN Data
IN10DATA
Endpoint 10 IN Data
IN11DATA
Endpoint 11 IN Data
IN12DATA
Endpoint 12 IN Data
IN13DATA
Endpoint 13 IN Data
IN14DATA
Endpoint 14 IN Data
IN15DATA
Endpoint 15 IN Data
Isochronous Byte Counts
OUT8BCH
EP8 Out Byte Count H
OUT8BCL
EP8 Out Byte Count L
OUT9BCH
EP9 Out Byte Count H
OUT9BCL
EP9 Out Byte Count L
EZ-USB Technical Reference Manual v1.10
D7
D6
D5
D4
D3
D2
D1
D0
Default
CPU
Access
d7
d7
d7
d7
d7
d7
d7
d7
d7
d7
d7
d7
d7
d7
d7
d7
d6
d6
d6
d6
d6
d6
d6
d6
d6
d6
d6
d6
d6
d6
d6
d6
d5
d5
d5
d5
d5
d5
d5
d5
d5
d5
d5
d5
d5
d5
d5
d5
d4
d4
d4
d4
d4
d4
d4
d4
d4
d4
d4
d4
d4
d4
d4
d4
d3
d3
d3
d3
d3
d3
d3
d3
d3
d3
d3
d3
d3
d3
d3
d3
d2
d2
d2
d2
d2
d2
d2
d2
d2
d2
d2
d2
d2
d2
d2
d2
d1
d1
d1
d1
d1
d1
d1
d1
d1
d1
d1
d1
d1
d1
d1
d1
d0
d0
d0
d0
d0
d0
d0
d0
d0
d0
d0
d0
d0
d0
d0
d0
xxxxxxxx
xxxxxxxx
xxxxxxxx
xxxxxxxx
xxxxxxxx
xxxxxxxx
xxxxxxxx
xxxxxxxx
xxxxxxxx
xxxxxxxx
xxxxxxxx
xxxxxxxx
xxxxxxxx
xxxxxxxx
xxxxxxxx
xxxxxxxx
RW
RW
RW
RW
RW
RW
RW
RW
RW
RW
RW
RW
RW
RW
RW
RW
d7
d7
d7
d7
d7
d7
d7
d7
d7
d7
d7
d7
d7
d7
d7
d7
d6
d6
d6
d6
d6
d6
d6
d6
d6
d6
d6
d6
d6
d6
d6
d6
d5
d5
d5
d5
d5
d5
d5
d5
d5
d5
d5
d5
d5
d5
d5
d5
d4
d4
d4
d4
d4
d4
d4
d4
d4
d4
d4
d4
d4
d4
d4
d4
d3
d3
d3
d3
d3
d3
d3
d3
d3
d3
d3
d3
d3
d3
d3
d3
d2
d2
d2
d2
d2
d2
d2
d2
d2
d2
d2
d2
d2
d2
d2
d2
d1
d1
d1
d1
d1
d1
d1
d1
d1
d1
d1
d1
d1
d1
d1
d1
d0
d0
d0
d0
d0
d0
d0
d0
d0
d0
d0
d0
d0
d0
d0
d0
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xxxxxxxx
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R
R
R
R
R
R
R
R
W
W
W
W
W
W
W
W
0
d7
0
d7
0
d6
0
d6
0
d5
0
d5
0
d4
0
d4
0
d3
0
d3
0
d2
0
d2
d9
d1
d9
d1
d8
d0
d8
d0
xxxxxxxx
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xxxxxxxx
R
R
R
R
Notes
CPU Access Codes
RW = Read or Write,
R, r = read-only,
W, w = write-only
b = both (Read & Write)
Appendix D - 59
EZ-USB Registers & Buffers
Addr
7F74
7F75
7F76
7F77
7F78
7F79
7F7A
7F7B
7F7C
7F7D
7F7E
7F7F
7F92
7F93
7F94
7F95
7F96
7F97
7F98
7F99
7F9A
7F9B
7F9C
7F9D
7F9E
7F9F
7FA0
7FA1
7FA2
7FA3
7FA4
7FA5
7FA6
7FA7
7FA8
7FA9
Name
OUT10BCH
OUT10BCL
OUT11BCH
OUT11BCL
OUT12BCH
OUT12BCL
OUT13BCH
OUT13BCL
OUT14BCH
OUT14BCL
OUT15BCH
OUT15BCL
Description
EP10 Out Byte Count H
EP10 Out Byte Count L
EP11 Out Byte Count H
EP11 Out Byte Count L
EP12 Out Byte Count H
EP12 Out Byte Count L
EP13 Out Byte Count H
EP13 Out Byte Count L
EP14 Out Byte Count H
EP14 Out Byte Count L
EP15 Out Byte Count H
EP15 Out Byte Count L
7F80-7F91 (reserved)
CPU Registers
CPUCS
Control & Status
PORTACFG
Port A Configuration
PORTBCFG
Port B Configuration
PORTCCFG
Port C Configuration
Input-Output Port Registers
OUTA
Output Register A
OUTB
Output Register B
OUTC
Output Register C
PINSA
Port Pins A
PINSB
Port Pins B
PINSC
Port Pins C
OEA
Output Enable A
OEB
Output Enable B
OEC
Output Enable C
(reserved)
Isochronous Control/Status Registers
ISOERR
ISO OUT Endpoint Error
ISOCTL
Isochronous Control
ZBCOUT
Zero Byte Count bits
(reserved)
(reserved)
I2C Registers
I2CS
Control & Status
I2DAT
Data
(reserved)
Interrupts
IVEC
Interrupt Vector
IN07IRQ
EPIN Interrupt Request
EZ-USB Technical Reference Manual v1.10
D7
0
d7
0
d7
0
d7
0
d7
0
d7
0
d7
D6
0
d6
0
d6
0
d6
0
d6
0
d6
0
d6
D5
0
d5
0
d5
0
d5
0
d5
0
d5
0
d5
D4
0
d4
0
d4
0
d4
0
d4
0
d4
0
d4
D3
0
d3
0
d3
0
d3
0
d3
0
d3
0
d3
D2
0
d2
0
d2
0
d2
0
d2
0
d2
0
d2
D1
d9
d1
d9
d1
d9
d1
d9
d1
d9
d1
d9
d1
D0
d8
d0
d8
d0
d8
d0
d8
d0
d8
d0
d8
d0
Default
xxxxxxxx
xxxxxxxx
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xxxxxxxx
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CPU
Access
R
R
R
R
R
R
R
R
R
R
R
R
rv3
RxD1out
T2OUT
RD
rv2
RxD0out
INT6
WR
rv1
FRD
INT5
T1
rv0
FWR
INT4
T0
0
CS
TxD1
INT1
0
OE
RxD1
INT0
CLK24OE
T1out
T2EX
TxD0
8051RES
T0out
T2
RxD0
( )0011
00000000
00000000
00000000
rrrrrrbr
RW
RW
RW
OUTA7
OUTB7
OUTC7
PINA7
PINB7
PINC7
OEA7
OEB7
OEC7
OUTA6
OUTB6
OUTC6
PINA6
PINB6
PINC6
OEA6
OEB6
OEC6
OUTA5
OUTB5
OUTC5
PINA5
PINB5
PINC5
OEA5
OEB5
OEC5
OUTA4
OUTB4
OUTC4
PINA4
PINB4
PINC4
OEA4
OEB4
OEC4
OUTA3
OUTB3
OUTC3
PINA3
PINB3
PINC3
OEA3
OEB3
OEC3
OUTA2
OUTB2
OUTC2
PINA2
PINB2
PINC2
OEA2
OEB2
OEC2
OUTA1
OUTB1
OUTC1
PINA1
PINB1
PINC1
OEA1
OEB1
OEC1
OUTA0
OUTB0
OUTC0
PINA0
PINB0
PINC0
OEA0
OEB0
OEC0
00000000
00000000
00000000
xxxxxxxx
xxxxxxxx
xxxxxxxx
00000000
00000000
00000000
RW
RW
RW
R
R
R
RW
RW
RW
ISO15ERR
*
EP15
ISO14ERR
*
EP14
ISO13ERR
*
EP13
ISO12ERR
*
EP12
ISO11ERR
PPSTAT
EP11
ISO10ERR
MBZ
EP10
ISO9ERR
MBZ
EP9
ISO8ERR
ISODISAB
EP8
xxxxxxxx
0000x000
xxxxxxxx
R
rrrrrbbb
R
START
d7
STOP
d6
LASTRD
d5
ID1
d4
ID0
d3
BERR
d2
ACK
d1
DONE
d0
000xx000
xxxxxxxx
bbbrrrrr
RW
0
IN7IR
IV4
IN6IR
IV3
IN5IR
IV2
IN4IR
IV1
IN3IR
IV0
IN2IR
0
IN1IR
0
IN0IR
00000000
00000000
R
RW
Notes
rv[3..0] = chip rev
0=port, 1=alt function
0=port, 1=alt function
0=port, 1=alt function
0=off, 1=drive
0=off, 1=drive
0=off, 1=drive
"MBZ" = Must Be Zero
1=request
Appendix D - 60
EZ-USB Registers & Buffers
Addr
7FAA
7FAB
7FAC
7FAD
7FAE
7FAF
7FB0
7FB1
7FB2
7FB3
7FB4
7FB5
7FB6
7FB7
7FB8
7FB9
7FBA
7FBB
7FBC
7FBD
7FBE
7FBF
7FC0
7FC1
7FC2
7FC3
7FC4
7FC5
7FC6
7FC7
7FC8
7FC9
7FCA
7FCB
7FCC
7FCD
7FCE
7FCF
7FD0
7FD1
7FD2
Name
OUT07IRQ
USBIRQ
IN07IEN
OUT07IEN
USBIEN
USBBAV
BPADDRH
BPADDRL
Bulk Endpoints 0-7
EP0CS
IN0BC
IN1CS
IN1BC
IN2CS
IN2BC
IN3CS
IN3BC
IN4CS
IN4BC
IN5CS
IN5BC
IN6CS
IN6BC
IN7CS
IN7BC
OUT0BC
OUT1CS
OUT1BC
OUT2CS
OUT2BC
OUT3CS
OUT3BC
OUT4CS
OU4TBC
OUT5CS
OUT5BC
OUT6CS
OUT6BC
OUT7CS
Description
EPOUT Interrupt Request
USB Interrupt Request
EP0-7IN Int Enables
EP0-7OUT Int Enables
USB Int Enables
Breakpoint & Autovector
(reserved)
(reserved)
Breakpoint Address H
Breakpoint Address L
Control & Status
Byte Count
Control & Status
Byte Count
Control & Status
Byte Count
Control & Status
Byte Count
Control & Status
Byte Count
Control & Status
Byte Count
Control & Status
Byte Count
Control & Status
Byte Count
(reserved)
Byte Count
Control & Status
Byte Count
Control & Status
Byte Count
Control & Status
Byte Count
Control & Status
Byte Count
Control & Status
Byte Count
Control & Status
Byte Count
Control & Status
EZ-USB Technical Reference Manual v1.10
D7
OUT7IR
*
IN7IEN
OUT7IEN
*
*
D6
OUT6IR
*
IN6IEN
OUT6IEN
*
*
D5
OUT5IR
*
IN5IEN
OUT5IEN
*
*
D4
OUT4IR
URESIR
IN4IEN
OUT4IEN
URESIE
*
D3
OUT3IR
SUSPIR
IN3IEN
OUT3IEN
SUSPIE
BREAK
D2
OUT2IR
SUTOKIR
IN2IEN
OUT2IEN
SUTOKIE
BPPULSE
D1
OUT1IR
SOFIR
IN1IEN
OUT1IEN
SOFIE
BPEN
D0
OUT0IR
SUDAVIR
IN0IEN
OUT0IEN
SUDAVIE
AVEN
Default
xxxxxxxx
00000000
00000000
00000000
00000000
xxxxxx00
CPU
Access
RW
RW
RW
RW
RW
RW
A15
A7
A14
A6
A13
A5
A12
A4
A11
A3
A10
A2
A9
A1
A8
A0
00000000
00000000
RW
RW
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
d6
*
d6
*
d6
*
d6
*
d6
*
d6
*
d6
*
d6
*
d5
*
d5
*
d5
*
d5
*
d5
*
d5
*
d5
*
d5
*
d4
*
d4
*
d4
*
d4
*
d4
*
d4
*
d4
*
d4
OUTBSY
d3
*
d3
*
d3
*
d3
*
d3
*
d3
*
d3
*
d3
INBSY
d2
*
d2
*
d2
*
d2
*
d2
*
d2
*
d2
*
d2
HSNAK
d1
in1bsy
d1
in2bsy
d1
in3bsy
d1
in4bsy
d1
in5bsy
d1
in6bsy
d1
in7bsy
d1
EP0STALL
d0
in1stl
d0
in2stl
d0
in3stl
d0
in4stl
d0
in5stl
d0
in6stl
d0
in7stl
d0
00001000
xxxxxxxx
00000000
xxxxxxxx
00000000
xxxxxxxx
00000000
xxxxxxxx
00000000
xxxxxxxx
00000000
xxxxxxxx
00000000
xxxxxxxx
00000000
xxxxxxxx
rrrrrrbb
RW
rrrrrrrb
RW
rrrrrrrb
RW
rrrrrrrb
RW
rrrrrrrb
RW
rrrrrrrb
RW
rrrrrrrb
RW
rrrrrrrb
RW
*
*
*
*
*
*
*
*
*
*
*
*
*
*
d6
*
d6
*
d6
*
d6
*
d6
*
d6
*
d6
*
d5
*
d5
*
d5
*
d5
*
d5
*
d5
*
d5
*
d4
*
d4
*
d4
*
d4
*
d4
*
d4
*
d4
*
d3
*
d3
*
d3
*
d3
*
d3
*
d3
*
d3
*
d2
*
d2
*
d2
*
d2
*
d2
*
d2
*
d2
*
d1
out1bsy
d1
out2bsy
d1
out3bsy
d1
out4bsy
d1
out5bsy
d1
out6bsy
d1
out7bsy
d0
out1stl
d0
out2stl
d0
out3stl
d0
out4stl
d0
out5stl
d0
out6stl
d0
out7stl
xxxxxxxx
00000010
xxxxxxxx
00000010
xxxxxxxx
00000010
xxxxxxxx
00000010
xxxxxxxx
00000010
xxxxxxxx
00000010
xxxxxxxx
00000010
RW
rrrrrrrb
RW
rrrrrrrb
RW
rrrrrrrb
RW
rrrrrrrb
RW
rrrrrrrb
RW
rrrrrrrb
RW
rrrrrrrb
Notes
1=request
1=request
1=enabled
1=enabled
1=enabled
1=enabled
For EP0IN and EP0OUT
* this bits are random
at power-on. Once
operational, these bits
read as zeros.
Appendix D - 61
EZ-USB Registers & Buffers
Addr
7FD3
7FD4
7FD5
7FD6
7FD7
7FD8
7FD9
7FDA
7FDB
7FDC
7FDD
7FDE
7FDF
7FE0
7FE1
7FE2
7FE3
7FE4
7FE5
7FE6
7FE7
7FE8
7FF0
7FF1
7FF2
7FF3
7FF4
7FF5
7FF6
7FF7
7FF8
7FF9
7FFA
7FFB
7FFC
7FFD
7FFE
7FFF
Name
OUT7BC
Global USB Registers
SUDPTRH
SUDPTRL
USBCS
TOGCTL
USBFRAMEL
USBFRAMEH
FNADDR
USBPAIR
IN07VAL
OUT07VAL
INISOVAL
OUTISOVAL
FASTXFR
AUTOPTRH
AUTOPTRL
AUTODATA
Setup Data
SETUPDAT
Isochronous FIFO Sizes
OUT8ADDR
OUT9ADDR
OUT10ADDR
OUT11ADDR
OUT12ADDR
OUT13ADDR
OUT14ADDR
OUT15ADDR
IN8ADDR
IN9ADDR
IN19ADDR
IN11ADDR
IN12ADDR
IN13ADDR
IN14ADDR
IN15ADDR
Description
Byte Count
D6
d6
D5
d5
D4
d4
D3
d3
D2
d2
D1
d1
D0
d0
A15
A7
WakeSRC
Q
FC7
0
A14
A6
*
S
FC6
0
A13
A5
*
R
FC5
0
A12
A4
*
IO
FC4
0
A11
A3
DisCon
0
FC3
0
A10
A2
DiscOE
EP2
FC2
FC10
A9
A1
ReNum
EP1
FC1
FC9
A8
A0
SIGRSUME
EP0
FC0
FC8
0
FA6
FA5
FA4
FA3
FA2
FA1
FA0
xxxxxxxx
R
ISOsend0
IN7VAL
OUT7VAL
IN15VAL
OUT15VAL
FISO
A15
A7
D7
*
IN6VAL
OUT6VAL
IN14VAL
OUT14VAL
FBLK
A14
A6
D6
PR6OUT
IN5VAL
OUT5VAL
IN13VAL
OUT13VAL
RPOL
A13
A5
D5
PR4OUT
IN4VAL
OUT4VAL
IN12VAL
OUT12VAL
RMOD1
A12
A4
D4
PR2OUT
IN3VAL
OUT3VAL
IN11VAL
OUT11VAL
RMOD0
A11
A3
D3
PR6IN
IN2VAL
OUT2VAL
IN10VAL
OUT10VAL
WPOL
A10
A2
D2
PR4IN
IN1VAL
OUT1VAL
IN9VAL
OUT9VAL
WMOD1
A9
A1
D1
PR2IN
1
1
IN8VAL
OUT8VAL
WMOD0
A8
A0
D0
0x000000
01010111
01010101
00000111
00000111
xxxxxxxx
xxxxxxxx
xxxxxxxx
xxxxxxxx
RW
RW
RW
RW
RW
RW
RW
RW
RW
8 bytes of SETUP data
d7
d6
d5
d4
d3
d2
d1
d0
xxxxxxxx
R
Endpt 8 OUT Start Addr
Endpt 9 OUT Start Addr
Endpt 10 OUT Start Addr
Endpt 11 OUT Start Addr
Endpt 12 OUT Start Addr
Endpt 13 OUT Start Addr
Endpt 14 OUT Start Addr
Endpt 15 OUT Start Addr
Endpt 8 IN Start Addr
Endpt 9 IN Start Addr
Endpt 10 IN Start Addr
Endpt 11 IN Start Addr
Endpt 12 IN Start Addr
Endpt 13 IN Start Addr
Endpt 14 IN Start Addr
Endpt 15 IN Start Addr
A9
A9
A9
A9
A9
A9
A9
A9
A9
A9
A9
A9
A9
A9
A9
A9
A8
A8
A8
A8
A8
A8
A8
A8
A8
A8
A8
A8
A8
A8
A8
A8
A7
A7
A7
A7
A7
A7
A7
A7
A7
A7
A7
A7
A7
A7
A7
A7
A6
A6
A6
A6
A6
A6
A6
A6
A6
A6
A6
A6
A6
A6
A6
A6
A5
A5
A5
A5
A5
A5
A5
A5
A5
A5
A5
A5
A5
A5
A5
A5
A4
A4
A4
A4
A4
A4
A4
A4
A4
A4
A4
A4
A4
A4
A4
A4
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
xxxxxxxx
xxxxxxxx
xxxxxxxx
xxxxxxxx
xxxxxxxx
xxxxxxxx
xxxxxxxx
xxxxxxxx
xxxxxxxx
xxxxxxxx
xxxxxxxx
xxxxxxxx
xxxxxxxx
xxxxxxxx
xxxxxxxx
xxxxxxxx
RW
RW
RW
RW
RW
RW
RW
RW
RW
RW
RW
RW
RW
RW
RW
RW
Setup Data Ptr H
Setup Data Ptr L
USB Control & Status
Toggle Control
Frame Number L
Frame Number H
(reserved)
Function Address
(reserved)
Endpoint Control
Input Endpoint 0-7 valid
Output Endpoint 0-7 valid
Input EP 8-15 valid
Output EP 8-15 valid
Fast Transfer Mode
Auto-Pointer H
Auto-Pointer L
Auto Pointer Data
(reserved)
(reserved)
EZ-USB Technical Reference Manual v1.10
Default
xxxxxxxx
CPU
Access
RW
D7
*
Notes
xxxxxxxx
RW
xxxxxxxx
RW
00000100 brrrbbbb Clear b7 by writing "1"
xxxxxxxx rbbbbbbb
xxxxxxxx
R
xxxxxxxx
R
PRx = 1 to pair EP
VAL =1 means valid
VAL =1 means valid
VAL =1 means valid
VAL =1 means valid
Appendix D - 62