PICDEM™ USB
User’s Guide
2001 Microchip Technology Inc.
DS41174A
Note the following details of the code protection feature on PICmicro ® MCUs.
•
•
•
•
•
•
The PICmicro family meets the specifications contained in the Microchip Data Sheet.
Microchip believes that its family of PICmicro microcontrollers is one of the most secure products of its kind on the market today,
when used in the intended manner and under normal conditions.
There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our knowledge, require using the PICmicro microcontroller in a manner outside the operating specifications contained in the data sheet.
The person doing so may be engaged in theft of intellectual property.
Microchip is willing to work with the customer who is concerned about the integrity of their code.
Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not
mean that we are guaranteeing the product as “unbreakable”.
Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of
our product.
If you have any further questions about this matter, please contact the local sales office nearest to you.
Information contained in this publication regarding device
applications and the like is intended through suggestion only
and may be superseded by updates. It is your responsibility to
ensure that your application meets with your specifications.
No representation or warranty is given and no liability is
assumed by Microchip Technology Incorporated with respect
to the accuracy or use of such information, or infringement of
patents or other intellectual property rights arising from such
use or otherwise. Use of Microchip’s products as critical components in life support systems is not authorized except with
express written approval by Microchip. No licenses are conveyed, implicitly or otherwise, under any intellectual property
rights.
Trademarks
The Microchip name and logo, the Microchip logo, PIC, PICmicro,
PICMASTER, PICSTART, PRO MATE, KEELOQ, SEEVAL,
MPLAB and The Embedded Control Solutions Company are registered trademarks of Microchip Technology Incorporated in the
U.S.A. and other countries.
Total Endurance, ICSP, In-Circuit Serial Programming, FilterLab,
MXDEV, microID, FlexROM, fuzzyLAB, MPASM, MPLINK,
MPLIB, PICC, PICDEM, PICDEM.net, ICEPIC, Migratable
Memory, FanSense, ECONOMONITOR, Select Mode, dsPIC,
rfPIC and microPort are trademarks of Microchip Technology
Incorporated in the U.S.A.
Serialized Quick Term Programming (SQTP) is a service mark
of Microchip Technology Incorporated in the U.S.A.
All other trademarks mentioned herein are property of their
respective companies.
© 2001, Microchip Technology Incorporated, Printed in the
U.S.A., All Rights Reserved.
Printed on recycled paper.
Microchip received QS-9000 quality system
certification for its worldwide headquarters,
design and wafer fabrication facilities in
Chandler and Tempe, Arizona in July 1999. The
Company’s quality system processes and
procedures are QS-9000 compliant for its
PICmicro ® 8-bit MCUs, KEELOQ® code hopping
devices, Serial EEPROMs and microperipheral
products. In addition, Microchip’s quality
system for the design and manufacture of
development systems is ISO 9001 certified.
DS41174A - page ii
2001 Microchip Technology Inc.
PICDEM™ USB USER’S GUIDE
Table of Contents
Preface
Introduction ................................................................................................ 1
Highlights ................................................................................................... 1
About This Guide ....................................................................................... 1
Warranty Registration ................................................................................ 3
Recommended Reading ............................................................................ 3
The Microchip Internet Web Site ............................................................... 4
Development Systems Customer Notification Service .............................. 5
Customer Support ..................................................................................... 7
Chapter 1. Getting Started with the PICDEM™ USB
1.1 Introduction .......................................................................................... 9
1.2 Highlights ............................................................................................. 9
1.3 Unpacking your PICDEM™ USB Kit ................................................... 9
1.4 Running the Default Demonstration .................................................. 10
1.5 Branching Out on Your Own ............................................................. 10
Chapter 2. USB Demonstration Code
2.1 Gameport - USB Translator ............................................................... 13
2.2 PS/2 Keyboard/Mouse - USB Translator ........................................... 17
2.3 Combination Gameport/PS/2/Mouse - USB Translator ..................... 23
2.4 Multi-Function LCD Text Display Example ........................................ 25
Chapter 3. PICDEM™ USB Hardware
3.1 Oscillator Support .............................................................................. 31
3.2 Connector Pinout ............................................................................... 32
3.3 Buttons and Jumpers ........................................................................ 36
3.4 Power ................................................................................................ 37
2001 Microchip Technology Inc.
DS41174A-page iii
PICDEM™ USB USER’S GUIDE
Chapter 4. Chapter 9 USB Firmware
4.1 Introducing the USB Software Interface ............................................39
4.2 Integrating USB Into Your Application ...............................................39
4.3 Interrupt Structure Concerns .............................................................40
4.4 File Packaging ...................................................................................41
4.5 Function Call Reference ....................................................................42
4.6 Behind the Scenes .............................................................................44
4.7 Examples ...........................................................................................45
4.8 Multiple Configuration or Report Descriptors .....................................46
4.9 Optimizing the Firmware ....................................................................47
4.10 Cursor Demonstration ......................................................................48
Chapter 5. Troubleshooting
5.1 Introduction ........................................................................................51
5.2 Highlights ...........................................................................................51
5.3 FAQ ...................................................................................................51
Appendix A. PICDEM™ USB Schematics
Introduction ..............................................................................................53
Highlights .................................................................................................53
Schematics ..............................................................................................54
Appendix B. PS/2 Lookup Tables
Introduction ..............................................................................................61
Scan Codes .............................................................................................61
Command Codes .....................................................................................62
Glossary
Introduction ..............................................................................................65
Highlights .................................................................................................65
PICDEM™ USB Terms ............................................................................65
Index .......................................................................................................... 73
Worldwide Sales and Service.................................................................. 76
DS41174A-iv
2001 Microchip Technology Inc.
PICDEM™ USB USER’S GUIDE
Preface
Introduction
This chapter contains general information about this manual and contacting
customer support.
Highlights
Topics covered in this chapter:
• About this Guide
• Warranty Registration
• Recommended Reading
• The Microchip Internet Web Site
• Development Systems Customer Notification Service
• Customer Support
About This Guide
Document Layout
This document describes how to use PICDEM™ USB to attach a new
peripheral to a PC. The manual layout is as follows:
• Chapter 1: Getting Started with the PICDEM™ USB – What
PICDEM™ USB is and how it works.
• Chapter 2: PICDEM™ USB Demonstration Code – Provides USB
demonstration code and information on Gameport™, PS/2® Keyboard/
Mouse, Combination Gameport/PS/2, and LCD Demo.
• Chapter 3: PICDEM™ USB Hardware – Contains oscillator support,
connector pinout, buttons and jumpers, and power information.
• Chapter 4: Chapter 9 USB Firmware – Describes the USB software
interface.
• Chapter 5: Troubleshooting – Provides solutions to common problems users may experience with PICDEM™ USB. It also includes FAQ
on Hardware, PC/Windows® and Macintosh® concerning the
PICDEM™ USB.
• Appendix A: Schematics – Provides the schematics for the
PICDEM™ USB.
• Appendix B: PS/2 Lookup Tables – Provides scan and command
code tables for easy reference.
2001 Microchip Technology Inc.
DS41174A-page 1
PICDEM™ USB User’s Guide
• Index – Provides a cross-reference listing of terms, features, and
sections of this document.
• PICDEM™ USB Worldwide Sales and Service – Lists Microchip sales
and service locations and telephone numbers worldwide.
Conventions Used in this Guide
This manual uses the following documentation conventions:
Documentation Conventions
Description
Represents
Examples
Code (Courier font):
Plain characters
Sample code,
file names and paths
#define START
c:\autoexec.bat
Angle brackets:
< >
Variables
<label>, <exp>
Square brackets [ ]
Optional arguments
MPASMWIN
[main.asm]
Curly brackets and
pipe character: { | }
Choice of mutually exclusive
arguments, an OR selection
errorlevel {0|1}
Lower case charac- Type of data
ters in quotes
"filename"
Ellipses...
Used to imply (but not show)
additional text that is not relevant to the example
list
["list_option..,
"list_option"]
0xnnn
A hexadecimal number where
’n’ is a hexadecimal digit
0xFFFF, 0x007A
Italic characters
A variable argument; it can be
either a type of data (in lower
case characters) or a specific
example (in uppercase
characters)
char isascii
(char, ch);
Interface (Arial font):
Underlined, italic
A menu selection from the
text with right arrow menu bar
File > Save
Bold characters
OK, Cancel
A window or dialog button to
click
Characters in angle A key on the keyboard
brackets < >
<Tab>, <Ctrl-C>
Documents (Arial font):
Italic characters
DS41174A-page 2
Referenced books
MPLAB® IDE User’s
Guide
2001 Microchip Technology Inc.
Preface
Updates
All documentation becomes dated, and this user’s guide is no exception.
Since the MPLAB IDE, PICDEM™ USB and other Microchip tools are
constantly evolving to meet customer needs, some MPLAB® dialogs and/or
tool descriptions may differ from those in this document. Please refer to our
web site at http://www.microchip.com to obtain the latest documentation
available.
Warranty Registration
Please complete the enclosed Warranty Registration Card and mail it
promptly. Sending in your Warranty Registration Card entitles you to receive
new product updates. Interim software releases are available at the Microchip
web site.
Recommended Reading
This user’s guide describes how to use PICDEM™ USB. The data sheets
contain current information on programming the specific microcontroller
devices.
README.USB
For the latest information on using PICDEM™ USB, read the README.USB
file (ASCII text file) included with the PICDEM™ USB software. The
README.USB file contains update information that may not be included in this
document.
MPLAB ® IDE User’s Guide (DS51025)
Comprehensive guide that describes installation and features of Microchip’s
MPLAB Integrated Development Environment (IDE), as well as the editor and
simulator functions in the MPLAB environment.
MPASM™ User’s Guide with MPLINK™ Linker and
MPLIB™ Librarian (DS33014)
Describes how to use Microchip Universal PICmicro® Microcontroller
Assembler (MPASM™), Linker (MPLINK™), and Librarian (MPLIB™).
Technical Library CD-ROM (DS00161)
This CD-ROM contains comprehensive data sheets for Microchip PICmicro®
MCU devices available at the time of print. To obtain this disk, contact the
nearest Microchip Sales and Service location (see back page), or download
individual data sheet files from the Microchip web site
(http://www.microchip.com).
2001 Microchip Technology Inc.
DS41174A-page 3
PICDEM™ USB User’s Guide
Embedded Control Handbook (DS00711)
This handbook consists of several documents that contain a wealth of
information about microcontroller applications. To obtain these documents,
contact the nearest Microchip Sales and Service location (see back page).
The application notes described in these manuals are also obtainable from
Microchip Sales and Service locations or from the Microchip web site
(http://www.microchip.com).
PICmicro™ Mid-Range MCU Family Reference Manual (DS33023)
This manual explains the general details and operation of the MCU family
architecture and peripheral modules. It is designed to complement the device
data sheets.
Microsoft® Windows® Manuals
This manual assumes that users are familiar with Microsoft Windows
operating system. Many excellent references exist for this software program,
and should be consulted for general operation of Windows.
USB Complete
This book is a good introduction to the USB interface and how to use it. It was
written by Jan Axelson.
PIC16C745/765 Data Book (DS41124)
This book contains everything you ever wanted to know about the
PIC16C745/765 and more.
USB IF
The USB IF can be downloaded from www.usb.org, which has all the
specifications for the USB interface. It is a valuable tool. Be sure to download
the USBCheck PC tools and register on the USB mailing list.
Microsoft DDK
If you are developing PC drivers for Windows, don’t forget to get the driver
development kit and the professional version of Visual Studio®.
Apple® USB Software Developer Kit (SDK)
If you are going to develop Mac drivers, go to
www.developer.apple.com/SDK/index.html and download the SDK
and register on the USB mailing list.
The Microchip Internet Web Site
Microchip provides online support on the Microchip World Wide Web (WWW)
site.
The web site is used by Microchip as a means to make files and information
easily available to customers. To view the site, the user must have access to
the Internet and a web browser, such as Netscape ® Communicator or
Microsoft® Internet Explorer®. Files are also available for FTP download from
our FTP site.
DS41174A-page 4
2001 Microchip Technology Inc.
Preface
Connecting to the Microchip Internet Website
The Microchip web site is available by using your favorite Internet browser
to attach to:
http://www.microchip.com
The file transfer site is available by using an FTP program/client to connect to:
ftp://ftp.microchip.com
The web site and file transfer site provide a variety of services. Users may
download files for the latest Development Tools, Data Sheets, Application
Notes, User's Guides, Articles, and Sample Programs. A variety of Microchip
specific business information is also available, including listings of Microchip
sales offices, distributors and factory representatives. Other data available for
consideration is:
• Latest Microchip Press Releases
• Technical Support Section with Frequently Asked Questions
• Design Tips
• Device Errata
• Job Postings
• Microchip Consultant Program Member Listing
• Links to other useful web sites related to Microchip Products
• Conferences for Products, Development Systems, Technical
Information and more
• Listing of Seminars and Events
Development Systems Customer Notification Service
Microchip started the customer notification service to help our customers
keep current on Microchip products with the least amount of effort. Once you
subscribe to one of our list servers, you will receive email notification
whenever we change, update, revise or have errata related to that product
family or development tool. See the Microchip web page at
http://www.microchip.com for other Microchip list servers.
The Development Systems list names are:
• Compilers
• Emulators
• Programmers
• MPLAB IDE
• Otools (other tools)
2001 Microchip Technology Inc.
DS41174A-page 5
PICDEM™ USB User’s Guide
Once you have determined the names of the lists that you are interested in,
you can subscribe by sending a message to:
[email protected]
with the following as the body:
subscribe <listname> yourname
Here is an example:
subscribe programmers John Doe
To UNSUBSCRIBE from these lists, send a message to:
[email protected]
with the following as the body:
unsubscribe <listname> yourname
Here is an example:
unsubscribe programmers John Doe
The following sections provide descriptions of the available Development
Systems lists.
Compilers
The latest information on Microchip C compilers, Linkers and Assemblers.
These include MPLAB® C17, MPLAB® C18, MPLINK™ Object Linker (as well
as MPLIB™ Object Librarian), and MPASM™ Assembler.
To SUBSCRIBE to this list, send a message to:
[email protected]
with the following as the body:
subscribe compilers yourname
Emulators
The latest information on Microchip In-Circuit Emulators. These include
MPLAB® ICE and PICMASTER® Emulator.
To SUBSCRIBE to this list, send a message to:
[email protected]
with the following as the body:
subscribe emulators yourname
Programmers
The latest information on Microchip PICmicro device programmers. These
include PRO MATE® II and PICDEM™ USB.
DS41174A-page 6
2001 Microchip Technology Inc.
Preface
To SUBSCRIBE to this list, send a message to:
[email protected]
with the following as the body:
subscribe programmers yourname
MPLAB IDE
The latest information on Microchip MPLAB IDE, the Windows Integrated
Development Environment for development systems tools. This list is focused
on MPLAB IDE, MPSIM™ Simulator, MPLAB’s Project Manager and general
editing and debugging features. For specific information on MPLAB
compilers, linkers and assemblers, subscribe to the COMPILERS list. For
specific information on MPLAB emulators, subscribe to the EMULATORS list.
For specific information on MPLAB device programmers, please subscribe to
the PROGRAMMERS list.
To SUBSCRIBE to this list, send a message to:
[email protected]
with the following as the body:
subscribe mplab yourname
Customer Support
Users of Microchip products can receive assistance through several
channels:
• Distributor or Representative
• Local Sales Office
• Field Application Engineer (FAE)
• Corporate Applications Engineer (CAE)
• Hotline
Customers should call their distributor, representative, or field application
engineer (FAE) for support. Local sales offices are also available to help
customers. See the back cover for a listing of sales offices and locations.
Corporate applications engineers (CAEs) may be contacted at
(480) 792-7627.
In addition, there is a Systems Information and Upgrade Line. This line
provides system users a listing of the latest versions of all of Microchip's
development systems software products. Plus, this line provides information
on how customers can receive any currently available upgrade kits.
The Hotline Numbers are:
1-800-755-2345 for U.S. and most of Canada, and
1-480-792-7302 for the rest of the world.
2001 Microchip Technology Inc.
DS41174A-page 7
PICDEM™ USB User’s Guide
NOTES:
DS41174A-page 8
2001 Microchip Technology Inc.
PICDEM™ USB USER’S GUIDE
Chapter 1. Getting Started with the PICDEM™ USB
1.1
Introduction
The Universal Serial Bus (USB) has become the most accepted way for any
new peripheral to be attached to a PC. The interface is fully supported by all
major computer manufacturers and most operating systems. Since this interface has become more accepted, it has moved out of the consumer market. It
is starting to find its way into data acquisition and industrial markets. Within
these markets, a large number of PICmicro solutions are looking for a migration path to USB. By providing a USB derivative of the classic PIC16C72/74
devices, Microchip encourages you to move your applications into the new
world of USB; and as an addition bonus, the examples provide an opportunity
to play games.
1.2
Highlights
The topics covered in this chapter are:
• Unpacking your PICDEM™ USB
• Running the Default Demonstration
• Branching out on your own
1.3
Unpacking your PICDEM™ USB Kit
1.3.1
Supplied Items
The items contained in your PICDEM™ USB box are:
• Microchip USB CD-ROM containing USB support documentation
• PICDEM™ USB Circuit Board with a PIC16C765 installed
• CD-ROM containing MPLAB IDE
• 3 ft. USB A-B cable
• Small box containing a windowed PIC16C745 and PIC16C765
1.3.2
Required Items
The items required are:
• PC for running MPLAB IDE
• Visual Basic and/or Visual C++ to modify the PC examples
• PC with USB running Windows® 98 or newer (for the PC examples)
• Macintosh with USB running MacOS X 10.0 or newer (for the Macintosh
examples). The HID examples work with MacOS 8.6 or newer.
• Apple® Project Builder to modify the Macintosh code examples
2001 Microchip Technology Inc.
DS41174A-page 9
PICDEM™ USB User’s Guide
• PICSTART® Plus or PRO MATE® II to program the devices
• UV chip eraser to clean the mistakes
• Copy of Apple’s USB DDK so you can use the USB bus monitoring
tools on the Macintosh (http://developer.apple.com/hardware/usb/)
• Copy of the USB-IF PC tools (www.usb.org)
1.3.3
Suggested Items
The items suggested are:
• USB protocol analyzer such as CATC
• Membership in the USB-IF, Inc. (www.usb.org)
• MPLAB® ICE 2000
1.4
Running the Default Demonstration
If you have a PC/Macintosh with USB, attach your PICDEM™ USB with the
supplied cable. The LED’s should quickly blink as the PICDEM™ USB identifies itself. The EP1 ACT light should start to flicker steadily, and the mouse
cursor on your computer should start to move in a circle.
Unplug the USB cable and plug a PS/2 mouse into the PS/2 connector. Reattach the USB cable. You will notice the mouse cursor is no longer moving in
a circle, but is responding to the mouse. Unplug the USB cable and plug in a
PS/2 keyboard. Re-attach the USB cable. The LED’s flicker and the keyboard
is functioning as a USB keyboard.
Regardless of what PS/2 device is attached (or not attached), the EP2 ACT
light will be flashing. This is due to the PICDEM™ USB constantly streaming
gameport data to the host, regardless of whether a gaming device is plugged
in or not. You can test the gameport by using the gamepad specified in
Section 2.1: Gameport - USB Translator.
This example takes advantage of the existing human interface device (HID)
code in the host’s operating system. For a more complex example showing
host driver code, you will have to consult the LCD Demo example.
1.5
Branching Out on Your Own
1.5.1
Developing New USB Applications
The following steps are recommended to develop most new USB
applications.
• Describe the application.
• Create the descriptors.
• Debug the report descriptor with dummy data.
• Develop the rest of the application.
DS41174A-page 10
2001 Microchip Technology Inc.
Getting Started with the PICDEM™ USB
By following these steps, the hardest part of the development can be completed right away on known good hardware (the PICDEM™ USB). After the
application is communicating to the PC correctly, the application specific
hardware and software can be developed.
1.5.1.1
Describing the Application
When you start developing your application, make sure that your data requirements fit the USB specification. A low speed device is limited to 2 channels of
communication (end points), with each channel limited to 800 bytes per
second. The most common mistake is to assume that the entire 1.5 Mbs is
available for your application.
1.5.1.2
Creating the Descriptors
The most difficult part of any USB application is determining what the device
descriptors should be. Every USB device communicates its requirements to
the host through a process called enumeration. During enumeration, the
device descriptors are transferred to the host and the host assigns a unique
address to the device. The descriptors are described in detail in Chapter 9 of
the USB 2.0 specification. Bundled with the USB tools CD, a descriptor tool is
provided to assist you in creating your own descriptors.
1.5.1.3
Debugging the Report Descriptor
The report descriptor allows HID devices to communicate to the host. The
report descriptor communicates the exact packet format of your data. This is
where the PC determines how large your packets will be. Report descriptors
range from the very specific (a multi-function joystick) to the very generic (a
specialized communications device for your application). Tools are available
to assist you in creating your report descriptors. The descriptor tool, which is
bundled in your kit, will have report descriptor capabilities with a future revision. After the report descriptor is written make sure that it is working with the
PC by using PC analysis tools. These are available from the USB-IF web site
for the PC, and Apple Computer for Macintosh machines. Use simple
counters and other dummy data to test report descriptor traffic. After the communications link is working, it will be much easier to develop the rest of the
application.
1.5.1.4
Developing the Rest of the Application
The next step is to add your specific hardware and software. Carefully study
the schematic in this guide and use the same circuitry for the USB connections. The circuitry will never change for this device. When your hardware is
built, you can be confident that your communications code will work because
it was developed on the development system with the same communications
circuitry.
2001 Microchip Technology Inc.
DS41174A-page 11
PICDEM™ USB User’s Guide
NOTES:
DS41174A-page 12
2001 Microchip Technology Inc.
PICDEM™ USB User’s Guide
Chapter 2. USB Demonstration Code
A variety of examples have been provided on the CD-ROM to speed you
towards a successful start with USB. These examples range from the very
basic gameport translator, to a very specialized LCD display. The gameport
and PS/2 examples are excellent tools to use, in order to become more familiar with report descriptors and basic USB communications. These basic
examples are extremely useful because the OS vendor has already written
generic Human Interface Device (HID) drivers. The LCD display example
does not have a generic PC driver. In this example, PC software has been
provided to demonstrate how you can develop your own PC applications to
interface to your device. Example code is provided for PC and Macintosh.
2.1
Gameport - USB Translator
2.1.1
Introduction
The gameport to USB translator is a simple example that reads a PC gameport and reports the information over USB. Since peripherals for gameports
come in all shapes and sizes, it is important to identify exactly what peripheral
is used, in this example -- the Dexxa® 8-button gamepad. Other gamepads
can be used, however, some change to the firmware functions may be
required. The example code will enumerate as a gamepad with 2 axis and 6
buttons. PORTA on the PICmicro MCU is used to read the analog voltages
from resistors in the direction pad (D-pad) and two of the buttons, while
PORTD reads the switches for the four remaining buttons. Refer to
Figure 2.1.
2001 Microchip Technology Inc.
DS41174A-page 13
PICDEM™ USB User’s Guide
TB
TA
D
F
E
D-PAD
C
A
B
Figure 2.1: Dexxa® Gamepad
Note:
2.1.2
Although the Dexxa® gamepad has 8 buttons, the code enumerates as a 6-button gamepad. This is due to the gamepad having
two “special” buttons, that rapidly fire two of the other button
outputs.
About the PC Gameport
The PC gameport was designed to support 2 joysticks. Each joystick was
intended to have 2 axis and 2 buttons. The gameport was later extended to
support a MIDI serial interface. The gameport hardware supplied with the
PICDEM™ USB does not support the MIDI interface, so those pins have
been disconnected. Two joysticks are supported, but to simplify the example,
only one joystick is used.
2.1.3
Hardware Implementation
The hardware is supplied on the PICDEM™ USB circuit board. The board is
wired with PORTA<3:0> and PORTD<3:0>, connected to the DB-15 connector of the gameport. PORTD<3:0> are the digital inputs for buttons A-D.
PORTA<0> and PORTA<1> are the X-Y inputs for the D-pad on the gamepad. PORTA<2> and PORTA<3> are the inputs for buttons E and F (see
Appendix A for the gamepad to PICDEM™ USB schematic). All of the analog
pins have a series resistor, a resistor, and capacitor tied to ground. The reason for this comes from the way analog pins were originally read by the PC.
The PC would clear a capacitor tied to ground at its end and then time how
long it took the capacitor to charge up. The capacitor would charge at a rate
proportional to the resistance of a pot, varied by one axis of the joystick, for
instance. This is legacy technology and is not needed when using a PICmicro
MCU with an analog-to-digital converter. As a result, the before mentioned
circuitry was put into place in order to obtain an analog output from the D-pad
of the gamepad and buttons E and F. Another point of confusion develops
from viewing the analog output of the gamepad with this circuitry in place. The
DS41174A-page 14
2001 Microchip Technology Inc.
USB Demonstration Code
voltage level is not symmetrical around 2.5 volts. You would expect the center
position of the D-pad’s x-axis, for instance, to output 2.5 volts, the left position
to output 0 volts and the right position to output 5 volts. Ideally it would, but
the circuitry in the gamepad is very simple; besides, this symmetry is not
needed. All that is needed is a lower voltage input into the PICmicro MCU
when the pad is pressed one direction from center, and a higher voltage input
when the pad is pressed in the other direction from center. The circuitry found
on the PICDEM™ USB board amplifies the differences in voltages between
these three positions and therefore, gives three very distinct analog-to-digital
readings.
Note 1: Buttons E and F are connected to analog pins because the
gameport has four analog pins and four digital pins. Buttons
A-D use up all the digital pins so the analog pins are the only
inputs left over. Many joysticks have a multiplexer on button
numbers greater than four, in order to achieve the same result
using just the digital pins.
2: Be very careful when using the LCD interface and the gameport
together because they share PORTD.
2.1.4
Gamepad Firmware
The firmware has four functions. Each function either returns one piece of
information concerning the gameport status, or initiates the gameport registers. Refer to Table 2.1.
Table 2.1: Gameport Firmware
2.1.5
Function
Description
ReadXAxis
Returns a digital value for the x-axis in W
ReadYAxis
Returns a digital value for the y-axis in W
ReadButtons
Returns the state of the six buttons in W (bits 0-5
correspond to buttons A-F)
InitGameport
Initialize the system to use the Gameport
Gamepad Report Descriptor
The report descriptor used in this example is for a gamepad with 6 buttons.
The minimum and maximum report values for the axis are set to 0 - 255. This
is to be used with Windows. Some versions don’t seem to handle a range of
-127 to 127. The -127 value is translated to 255 and causes extreme movement to the right. The range selected works correctly on Windows and on
Macintosh. Interestingly, the Macintosh performs a simple filter on the center
of the range. It will filter changes of 1 count to prevent cursor jitter when the
stick is centered. This caused problems with a minimum and maximum range
of 0 - 2. When the range was extended to 0 - 4, it worked much better. In this
example, the analog input from the D-pad will be converted to digital, filtered,
and then sent to the PC via USB. Since this digital value can range from
2001 Microchip Technology Inc.
DS41174A-page 15
PICDEM™ USB User’s Guide
0 - 255, the descriptor calls for a range of 0 - 255. The descriptor, shown
below in HEX form, is in the gamepad descriptor file (usb_ch9.asm).
0x05,
0x09,
0xA1,
0x09,
0xA1,
0x09,
0x09,
0x15,
0x26,
0x75,
0x95,
0x81,
0xC0
0x05,
0x19,
0x29,
0x15,
0x25,
0x75,
0x95,
0x81,
0x95,
0x81,
0xC0
0x01
0x05
0x01
0x01
0x00
0x30
0x31
0x00
0xFF, 0x00
0x08
0x02
0x02
0x09
0x01
0x06
0x00
0x01
0x01
0x06
0x02
0x02
0x03
USAGE_PAGE (Generic Desktop)
USAGE (Game Pad)
COLLECTION (Application)
USAGE (Pointer)
COLLECTION (Physical)
USAGE (X)
USAGE (Y)
LOGICAL_MINIMUM (0)
LOGICAL_MAXIMUM (255)
REPORT_SIZE (8)
REPORT_COUNT (2)
INPUT (Data,Var,Abs)
END_COLLECTION
USAGE_PAGE (Button)
USAGE_MINIMUM (Button 1)
USAGE_MAXIMUM (Button 6)
LOGICAL_MINIMUM (0)
LOGICAL_MAXIMUM (1)
REPORT_SIZE (1)
REPORT_COUNT (6)
INPUT (Data,Var,Abs)
REPORT_COUNT (2)
INPUT (Constant,Var,Abs)
END_COLLECTION
This report descriptor describes the packet format for the USB data. The data
is filled from Least Significant Byte, Least Significant bit through to the Most
Significant Byte, Most Significant bit. The first field found will be the first bit/
byte. In the report descriptor above, the first data is 8 bits (the REPORT_SIZE
is 8) and it is the X axis (the first USAGE of the physical collection is X). So the
first byte on the bus will be the X axis value. The second byte will be the Y
axis. The third byte will be button A in bit 0, followed by button B in bit 1, and
so on. Because every USB transaction must be in whole number bytes, the
data is padded by one constant report, 2-bits long.
2.1.6
Gameport Translation
Translating the bits from the physical hardware to the USB buffer is very simple. Because we set the logical minimum and maximum to be 0 to 255, it
exactly matches the scaling of the analog-to-digital converter. So first, we
convert the X and Y axis and store the values in the first two buffer locations.
Secondly, we read the six buttons and store the values in the third buffer location in bits 0-5. Lastly, we inform the serial interface engine that data is
available and wait for the host PC to come pick it up.
DS41174A-page 16
2001 Microchip Technology Inc.
USB Demonstration Code
2.1.7
Vendor/Product Identification
Besides the report information, the descriptors also contain manufacturing
and product identification codes. Microchip has a registered Vendor ID with
the USB IF forum, which identifies Microchip’s Vendor ID as 0x04D8. You are
allowed to use this ID for your own testing, but you may not ship any products
with this code without written permission from Microchip. Microchip has
defined product ID’s for each demonstration code included in this kit. As additional demonstration devices are released, Microchip will ensure that no
duplicate ID’s are used.
2.2
PS/2 Keyboard/Mouse - USB Translator
2.2.1
Introduction
This is the demonstration firmware that is programmed into the PIC16C765
and installed on the PICDEM™ USB demonstration board. The PS/2 connector was added so PS/2 mice and keyboards could be translated to USB.
Again, this is a straightforward application intended to provide practice with
device descriptors. The PS/2 interface is a synchronous serial interface with
different data protocols for keyboards and mice. Device descriptors in the
PICmicro microcontroller allows the unit to report itself as either a keyboard or
a mouse. When a mouse is attached to a PS/2 port, it identifies itself as a
mouse. When the PICmicro MCU receives this identification, it will perform a
soft detach from the USB bus and re-attach as a mouse. When the PICmicro
MCU identifies the PS/2 device as a keyboard, it will perform a soft detach
and re-attach as a keyboard. Using soft detach may be a useful feature in
your application, so you can practice using it with this example.
Note:
2.2.2
It may be necessary to attach 110 kOhm pull-down resistors on
RC0 and RC1, in order for auto-detect to work without pressing
MCLR between plugging and unplugging PS/2 devices.
About the PS/2 Port
IBM® originally developed the PS/2 port for use on its PS/2 family of computers. This port is a synchronous serial port clocked by the PS/2 device (keyboard/mouse). Generally, PC’s have two PS/2 ports labeled as keyboard or
mouse. The PICDEM™ USB only has one PS/2 port. Since the hardware is
the same, either the keyboard or mouse can be used, simply by interpreting
the data correctly.
2.2.3
Hardware Implementation
The PS/2 port is a 6-pin DIN which only uses 4 pins. The pins are used for
power, ground, clock, and data. Power and ground pins are directly tied to VDD
and VSS. If power management is desired, the power pins must be driven via
switches from other I/O pins.The clock pin is connected to RC0, while the data
pin is connected to RC1. The PS/2 device clocks the host even when it is receiving data. The data pin is used to send and receive data from the keyboard.
2001 Microchip Technology Inc.
DS41174A-page 17
PICDEM™ USB User’s Guide
2.2.4
Data Format
The data is sent via PS/2 one byte at a time, regardless of direction, host-todevice, or vice versa. The data is as follows:
• First comes a START bit (always low), followed by a
• data byte (Least Significant bit to Most Significant bit), then by a
• parity bit (high for an even number of high bits in the data byte and low
for an odd number), then by a
• STOP bit (always high)
In the case of host-to-device communication, the STOP bit is immediately followed by an ACK bit (low), which is sent by the device to the host. The bits
are read on the falling edge of the clock for device-to-host communication
and on the rising edge for host-to-device communication. In the IDLE state,
the clock and data lines are held high by the device. See Figure 2.2 and
Figure 2.3 for device-to-host and host-to-device communication, respectively.
Clock
STOP
PAR-
DATA
DATA
DATA
DATA
DATA
DATA
DATA
DATA
STAR
Data
Figure 2.2: Device-to-Host Communication
(Data bit Read on Falling Edge of Clock)
Clock
ACK
STOP
PAR-
DATA
DATA
DATA
DATA
DATA
DATA
DATA
DATA
STAR
Data
Figure 2.3: Host-to-Device Communication
(Data bit Read on Rising Edge of Clock)
DS41174A-page 18
2001 Microchip Technology Inc.
USB Demonstration Code
2.2.5
Keyboard
The PS/2 keyboard data report format is summarized for every key in
Appendix B. Make codes are the byte or bytes that the PS/2 keyboard sends
to the host when a certain key is pressed. Break codes are the bytes that the
PS/2 keyboard sends when the user releases a key. If the user does not
release a specific key for several hundreds of a millisecond, the make code
will be sent repeatedly until the user releases the key. At this point, the break
code is sent. The Translation to USB, Section 2.2.11, details how the
firmware converts PS/2 keycodes to USB keycodes.
Note:
2.2.6
The PS/2 keycodes shown in Appendix B do not apply to all PS/2
keyboards. Several code sets have been used through the years.
However, this code set is the most common.
Mouse
Table 2.2 details a typical PS/2 mouse data format.
Table 2.2: PS/2 Mouse Data Report Format
2.2.7
Byte
Bit
Description
3
7
6-1
0
MSB of Y Data
Y Data
LSB of Y Data
2
7
6-1
0
MSB of X Data
X Data
LSB of X Data
1
7
6
5
4
3
2
1
0
Y Data Overflow, 1 = overflow
X Data Overflow, 1 = overflow
Y Data Sign, 1 = negative
X Data Sign, 1 = negative
Reserved
Reserved
Right Button Status, 1 = pressed
Left Button Status, 1 = pressed
Hardware Implementation
A PS/2 port is a 6-pin DIN, but only four pins are used (see Appendix A for
pinout.) The pins are power, ground, clock and data. The clock pin is connected to RC0, while the data pin is connected to RC1. A PS/2 device clocks
the host even when it is receiving data. By attaching the data pin to RC1, a
START bit will interrupt the PICmicro MCU through a Capture/Compare/PWM
(CCP) event. Refer to the PIC16C7XX data sheet for details on CCP. Power
and ground are directly tied to VDD and VSS. If power management were
desired, the power pins would be driven via switches from other I/O pins.
2001 Microchip Technology Inc.
DS41174A-page 19
PICDEM™ USB User’s Guide
2.2.8
PS/2 Firmware
The PS/2 firmware is entirely interrupt driven. As mentioned before, an interrupt is generated when the START bit is received, at which time the firmware
will begin its receive routine. In addition to this interrupt, every 168 ms, a timer
overflow interrupts the normal program flow and implements one state of the
mouse/keyboard/cursor demonstration state machine. This state machine
handles sending bytes to and translating bytes received from the PS/2
device, automatically. These two interrupts essentially handle everything,
except for transferring the bytes via USB to the PC. In addition, it does all of
this work in the background while a developer’s code runs in the foreground.
The only operation that the developer’s program must implement is sending
keyboard or mouse data to the PC via USB. The developer needs only to be
concerned with the TYPE and eight BUFFER registers. BUFFER registers 0
to 7 are the registers where translated PS/2 device data gets placed. TYPE
contains the following status bits:
Table 2.3: PS/2 State Machine Status Report
2.2.9
TYPE bit Name
Description
0
CONNECTED
1 = device connected
1
MOUSE
1 = device connected is a mouse
2
KEYBOARD
1 = device connected is a keyboard
3
DATA READY
1 = data is ready; must be cleared by user
Report Descriptor
The report descriptors used in the example code for both the keyboard and
mouse were copied directly out of the HID Usage Tables. The HID Usage
Tables document is published by the USB Implementers Forum
(www.usb.org). Many other useful HID report descriptor examples can be
found in this document. The keyboard and mouse report descriptors are not
sent out at the same time that the PICmicro MCU is enumerated by the host.
Rather, the PICmicro MCU will only send the report descriptor that corresponds to the device it has detected as being attached at that time.
2.2.9.1
0x05,
0x09,
0xA1,
0x05,
0x19,
0x29,
0x15,
0x25,
0x75,
0x95,
0x81,
DS41174A-page 20
Keyboard Descriptor
0x01
0x06
0x01
0x07
0xE0
0xE7
0x00
0x01
0x01
0x08
0x02
usage page (generic desktop)
usage (keyboard)
collection (application)
usage page (key codes)
usage minimum (224)
usage maximum (231)
logical minimum (0)
logical maximum (1)
report size (1)
report count (8)
input (data, variable, absolute)
2001 Microchip Technology Inc.
USB Demonstration Code
0x95,
0x75,
0x81,
0x95,
0x75,
0x05,
0x19,
0x29,
0x91,
0x95,
0x75,
0x91,
0x95,
0x75,
0x15,
0x25,
0x05,
0x19,
0x29,
0x81,
0xC0
0x01
0x08
0x01
0x05
0x01
0x08
0x01
0x05
0x02
0x01
0x03
0x01
0x06
0x08
0x00
0x65
0x07
0x00
0x65
0x00
2.2.9.2
0x05,
0x09,
0xA1,
0x09,
0xA1,
0x05,
0x19,
0x29,
0x15,
0x25,
0x95,
0x75,
0x81,
0x95,
0x75,
0x81,
0x05,
0x09,
0x09,
0x15,
0x25,
0x75,
0x95,
0x81,
0xC0
0xC0
2001 Microchip Technology Inc.
report count (1)
report size (8)
input (constant)
report count (5)
report size (1)
usage page (page# for Led)
usage minimum (1)
usage maximum (5)
output (data, variable, absolute)
report count (1)
report size (3)
output (constant)
report count (6)
report size (8)
logical minimum (0)
logical maximum (101)
usage page (key codes)
usage minimum (0)
usage maximum (101)
input (data, array)
end collection
Mouse Descriptor
0x01
0x02
0x01
0x01
0x00
0x09
0x01
0x03
0x00
0x01
0x03
0x01
0x02
0x01
0x05
0x01
0x01
0x30
0x31
0x81
0x7F
0x08
0x03
0x06
usage page (generic desktop)
usage (mouse)
collection (application)
usage (pointer)
collection (linked)
usage page (buttons)
usage minimum (1)
usage maximum (3)
logical minimum (0)
logical maximum (1)
report count (3)
report size (1)
input (3 button bits)
report count (1)
report size (5)
input (constant 5 bit padding)
usage page (generic desktop)
usage (X)
usage (Y)
logical minimum (-127)
logical maximum (127)
report size (8)
report count (2)
input (2 position bytes X & Y)
end collection
end collection
DS41174A-page 21
PICDEM™ USB User’s Guide
2.2.10
Soft Detach
The soft detach command is one of the most useful features on the USB
PICmicro MCU. The reason the soft detach command is so useful is that in
applications such as the PS/2 mouse/keyboard example, no special driver
has to be created for the host. Most often for this application, the PICmicro
MCU would have two configurations - one for a mouse and the other for a
keyboard. A special driver would have to be created for the host that would
instruct the PICmicro MCU to change configurations. Furthermore, in order to
do this, the host’s driver would have to be able to detect what peripheral is
attached. An easy way to avoid difficulty with creating a unique driver for the
host, is to give the PICmicro MCU control over whether it will send the host
mouse or keyboard data. Based on the type of data it will send to the PC, the
PICmicro MCU can soft detach and re-enumerate as the peripheral of choice.
In this example, several events precede the implementation of a soft detach.
As mentioned before, an interrupt is generated when the data line goes low.
This initiates the receive routine, because it is assumed that the data line
dropping low is the result of a START bit being sent by the device. However,
the data line will also drop if the user disconnects the device. To distinguish
between these two cases, the firmware starts a timer when the data line goes
low. If the timer times out before the clock line goes high, the device has been
disconnected. Otherwise, the data line going low is the result of a START bit.
Once it has been determined that a device has been disconnected, the firmware waits for another device to be attached. When the clock and data lines
are both high, a device has been attached. At this point, the PICmicro MCU
will ask the device to identify itself (see Appendix B for keyboard and mouse
commands). Based on the device’s response, the firmware will know whether
the newly attached device is a keyboard or mouse and perform a soft detach.
During the soft detach process, several things occur. First, the PICmicro MCU
turns off the pull-up resistor to VUSB. The firmware does this by clearing the
DEV_ATT bit. Turning the pull-up resistor off, removes the PICmicro MCU
from the bus. After approximately 50 ms, which is enough time for the host to
see the device disconnect, the firmware sets DEV_ATT and reconnects the
PICmicro MCU to the bus. The host then re-enumerates the PICmicro MCU.
2.2.11
Translation to USB
In order to act like a USB mouse or keyboard, the PICmicro MCU has to
translate the PS/2 data format for each device to its USB data format. For the
mouse, this is very simple. For the keyboard, however, the process is more
complex.
DS41174A-page 22
2001 Microchip Technology Inc.
USB Demonstration Code
2.2.11.1 Keyboard
Incoming PS/2 data can be one to eight bytes long. No pattern or mathematical expression can be used to convert incoming PS/2 data to a USB keycode.
USB keycodes are one byte in length. There is one USB keycode for every
key on the keyboard. A lengthy lookup table is used to implement the translation from PS/2 to USB keycodes. The lookup table is found in file
table_kb.asm of the example firmware. The USB keycodes are shown in
Section 9 of the HID Usage Tables document.
2.2.11.2 Mouse
The mouse translation from a PS/2 format to a USB format is very simple. The
PS/2 button states are simply copied into the correct bits in the USB buffer.
The data overflow and data sign bits in the first PS/2 byte are not necessary
and are therefore, not transferred to the corresponding USB byte. The X-axis
bytes are identical in both the PS/2 and USB data formats. The PS/2 Y-axis
byte is complimented in order to mirror the byte and is then passed into the
last byte of the USB mouse data. This makes three bytes of USB mouse data.
You may notice, however, that four bytes are sent to the PC in the example
code. This is because a mouse is unique, in that it is a boot device and as
such, has a stringent format defined for it. This format requires that four bytes
always be sent, despite the possibility that the last byte may not be needed
for a particular mouse. This fourth byte is reserved for the scrolling wheel
found on some mice.
2.3
Combination Gameport/PS/2/Mouse - USB
Translator
2.3.1
Introduction
The low speed USB interface has two endpoints. Each endpoint can be configured for transmit or receive, but not both. Each endpoint has its own report
descriptor. This example shows how you can create a combination device
that provides a completely different interface over two different endpoints. A
gamepad is reported on EP2 while EP1 reports a mouse.
2.3.2
Using Multiple Endpoints
There is a hierarchy of descriptors for every USB device. For a HID device
that uses only one interface, the hierarchy is shown in Figure 2.4. During enumeration, the host will ask the device for its descriptors with the following
sequence of requests.
1.
2.
3.
4.
2001 Microchip Technology Inc.
Get_Device_Descriptor
Get_Configuration_Descriptor
Get_Report_Descriptor
Get_String_Descriptor
DS41174A-page 23
PICDEM™ USB User’s Guide
The device will send out its configuration, interface, HID, and endpoint
descriptors (in that order), when it receives the Get_Configuration_Descriptor
request. Therefore, you'll find in the firmware that these descriptors fall
between the labels Config1 and EndConfig1. In the case of two interfaces,
shown in Figure 2.5, the device sends the host the configuration, interface1,
HID1, endpoint1, interface2, HID2, and endpoint2 descriptors (in that order),
in response to the Get_Configuration_Descriptor request. In this example,
interface1 is a mouse that sends data over EP1, and interface2 is a gamepad
communicating with the host over EP2. Each interface requires its own report
descriptor.
device
configuration
interface
endpoint
HID
report
Figure 2.4: One Interface
device
configuration
interface1
HID1
endpoint1
interface2
endpoint2
HID2
report2
report1
Figure 2.5: Two Interfaces
DS41174A-page 24
2001 Microchip Technology Inc.
USB Demonstration Code
There is no way to tell what endpoint a report descriptor is associated with by
looking at the report descriptor. In other words, unlike other descriptor types,
report descriptors do not have a field that identifies them as a report descriptor. Nor do report descriptors have an index number that distinguishes one
from another. Report descriptors are associated with the appropriate endpoint
in the firmware with the use of a Report Descriptor Index.
Looking at Figure 2.5 again, you can see that HID1 is associated with
endpoint1 and that HID1 specifies that it has a report descriptor. The host
assigns this report descriptor an index value of 0 (this is a zero based array),
simply because the HID1 descriptor is the first descriptor sent to the host that
specifies a report descriptor. Similarly, the host assigns the report descriptor
specified by HID2 an index value of 1. The host keeps track of what descriptors branch off a particular interface, therefore, the host is able to deduce that
report descriptors with indexes 0 and 1 are describing the communication that
will take place over endpoint1 and endpoint2, respectively. The host will call
these report descriptors with the Get_Report_Descriptor request. As part of
this request, the host specifies the index number of the descriptor it desires.
It's up to the developer to make sure that Report Descriptor 1 is sent to the
host when index 0 is specified in the request, and Report Descriptor 2 is sent
to the host when index 1 is specified. To make this process as painless as
possible, the Report Descriptor Index in file descript.asm was created. In
this index, all that is needed, is for you to list the labels of your report descriptors in the order that the corresponding HID descriptors are sent to the host.
2.4
Multi-Function LCD Text Display Example
2.4.1
Introduction
USB endpoints can be used to send data from the host as well as receive
data from a device. In this example, a simple vendor defined protocol is used
to draw text on the LCD. Additional commands are provided to move the cursor around, clear the screen, download custom font characters, send data
through the serial port, and light LED’s on PORTB. This example does not
use the alphanumeric HID class defined by the USB-IF. This example used
the second endpoint to provide additional functionality. The second endpoint
will receive serial data from the UART and read the analog-to-digital
converter.
2.4.2
Hardware Implementation
The hardware is simply the PICDEM™ USB with an LCD character module
attached to the LCD connector. The LCD control signals are PORTE, while the
data is PORTD. Provision is in place for backlight power on the PICDEM™
USB, but backlight control is not provided. If you use an LCD with an LED
backlight, your board could draw slightly more than 100 mA. Fortunately, current PC drivers will not shut-down the device for using too much current,
unless the current draw from all the USB ports or a hub exceeds 500 mA.
Future PC drivers may require additional power management capabilities.
2001 Microchip Technology Inc.
DS41174A-page 25
PICDEM™ USB User’s Guide
The LCD module used is a standard 2x16 character module, which uses a
Hitachi 44780 controller.
2.4.3
LCD Driver Firmware
The lcd.asm file contains the LCD firmware. For additional information on
the LCD features and command set, consult the documentation for the
Hitachi 44780 controller. The firmware provides the following functions to the
rest of the USB application.
Table 2.4: LCD Driver Firmware
Command
Function
LCDINIT
Initializes the LCD in 8-bit mode, clears the screen and
hides the cursor.
LCDCLEAR
Clears the display and homes the cursor.
LCDHOME
Homes the cursor without clearing the display.
LCDEMODE
Sets the entry mode of the display.
Required entry mode must be set in W.
b0 : 0 = no display shift 1 = display shift
b1 : 0 = auto-decrement 1 = auto-increment
b2-7 : not used
LCDDMODE
Sets the display control.
Required display mode must be set in W.
b0 : 0 = cursor blink off 1 = cursor blink on
b1 : 0 = cursor off
1 = cursor on
b2 : 0 = display off
1 = display on (display data is
intact)
b3-7 : not used
LCDSCGA
Sets the LCD Character RAM Address to the value in W.
This prepares the display to accept font data at the indicated address.
LCDSDDA
Sets the LCD Data RAM Address to the value in W. This
prepares the display to accept characters at the indicated
cursor address. It can also be used to move the cursor
around the screen.
LCDADDR
Returns the current address in W. Useful for saving the
current cursor position before updating the font data.
LCDPUTCHAR
Writes the character in W to the current data memory
address. Causes a character to be placed on the screen.
LCDPUTCMD
Writes the byte in W to the command memory. This is
used to implement most of the previous commands. This
won’t be used frequently but if you want to use a specific
feature of the display, this is where to look.
Any LCD operation can be performed with these functions. The LCD firmware
supplied is a linkable file (lcd.asm).
DS41174A-page 26
2001 Microchip Technology Inc.
USB Demonstration Code
2.4.4
LCD Report Descriptor
The report descriptor for this example is very simple; a vendor defined usage
page and a vendor defined usage with an 8-byte payload. Two reports are
defined, one for input and one for output. The report formats are identical.
dt
dt
dt
dt
dt
dt
dt
dt
dt
dt
dt
dt
dt
dt
2.4.5
006h,
009h,
0a1h,
019h,
029h,
015h,
026h,
075h,
095h,
081h,
019h,
029h,
091h,
0c0h
000h, 0ffh ; USAGE_PAGE (Vendor Defined
001h
; USAGE (Vendor Usage 1)
001h
; COLLECTION (Application)
001h
;
USAGE_MINIMUM (Vendor
008h
;
USAGE_MAXIMUM (Vendor
000h
;
LOGICAL_MINIMUM (0)
0ffh, 000h ;
LOGICAL_MAXIMUM (255)
008h
;
REPORT_SIZE (8)
008h
;
REPORT_COUNT (8)
002h
;
INPUT (Data,Var,Abs)
001h
;
USAGE_MINIMUM (Vendor
008h
;
USAGE_MAXIMUM (Vendor
002h
;
OUTPUT (Data,Var,Abs)
; END_COLLECTION
Page 1)
Usage 1)
Usage 8)
Usage 1)
Usage 8)
USB Command Set
The USB command set implementation is simple. The first byte in the packet
is the command byte, while the remaining seven bytes contain data. The
command byte has a command number in the low nibble, while the upper nibble contains a command modifier. Although six commands are implemented,
sixteen commands are available.
Table 2.5: USB Command Set
Command
Number
Command Name
Function
0
Clear Display
This command clears the display and
homes the cursor. No additional data is
required so the data bytes are ignored.
1
Move Cursor
This command moves the cursor to the
indicated row and column. The row is
specified in the first data byte while the
column is specified in the second data
byte. The row byte is limited to 2 rows.
This code works on a 2x20 LCD. It
should also work on a 2x16 LCD.
Beyond that, expect to modify the code.
2
Write Text
This commands writes the N characters
to the current cursor position.
N is the value in the upper nibble of the
command and cannot exceed 7.
The data is in the 7 data bytes following
the command.
2001 Microchip Technology Inc.
DS41174A-page 27
PICDEM™ USB User’s Guide
Table 2.5: USB Command Set (Continued)
DS41174A-page 28
Command
Number
Command Name
Function
3
CGRAM Data
This command modifies one of the eight
programmable characters in the character generator RAM. The upper nibble
defines which character is to be modified. The remaining 7 bytes contain the
data. The data is formatted as a 5x7 bit
array. The 7 bytes are the 7 rows. Only
the 5 LSB’s are used in each byte. The
top row is the first byte.
4
Serial Data
This command works the same way as
the Write Text command. The number of
bytes to send is the upper nibble. The
data is sent through the serial port at
28800 8n1.
5
LED Data
If the LED’s are not being used by the
Chapter 9 firmware, you can light the
LED’s with the contents of data byte 0.
This command simply copies the data
byte to PORTB.
6-15
Unused
Unused
2001 Microchip Technology Inc.
USB Demonstration Code
2.4.5.1
Input Commands
The input pipe will send these commands in random order depending on
when data is present.
Table 2.6: Input Commands
2.4.6
Command
Command Name
Number
Function
0
Unused
Unused
1
Unused
Unused
2
Unused
Unused
3
Unused
Unused
4
Serial Data
Pass up to 7 serial characters back to the
host. Total number of characters is in the
high nibble. Characters queue until the host
asks for them. Baud rate is 28800 8n1.
5
Unused
Unused
6
Unused
Unused
7
ADC Data
Pass 5 bytes of ADC data. Each byte
comes from a different ADC channel.
Channels AN0-AN4 are read.
8-15
Unused
Unused
PC Code Support
The PC code is written with Visual Basic using an ActiveX® control for the
USB interface. The ActiveX control is based on the code in USB Complete by
Jan Axelson. The PC code interfaces to this example through the windows
HID API. Unfortunately, the HID API’s don’t provide direct access to the
endpoints.
2001 Microchip Technology Inc.
DS41174A-page 29
PICDEM™ USB User’s Guide
2.4.7
Macintosh Code Support
Macintosh computers have supported USB since the introduction of the iMac®
and MacOS version 8.6. Operating systems prior to MacOS X are referred to
as the "Classic" environment.
2.4.7.1
MacOS 8.6 through 9.1
At this time, no examples are available for the older "Classic" versions of the
Macintosh operating system. Consult Apple’s USB software development kit
for help in creating applications for these operating systems.
2.4.7.2
MacOS X
The MacOS X code is based on the simple example code supplied with the
USB DDK from Apple Computer. This example interfaces directly with the
USB layer in the operating system, which bypasses the HID system. The
advantage to this method is the direct access to the endpoints. Fortunately,
this level of access is available from a user program and a kernel level device
driver is not required.
DS41174A-page 30
2001 Microchip Technology Inc.
PICDEM™ USB User’s Guide
Chapter 3. PICDEM™ USB Hardware
3.1
Oscillator Support
The PIC16C745/765 can support a few different oscillator options. Regardless of what oscillator is used, the internal clock must be 24 MHz. This is
required by the USB Serial Interface Engine (SIE). To assist in running at
24 MHz with a low cost oscillator, the HS and EC clock modes are provided
with an internal 4x PLL clock multiplier. This allows 6 MHz oscillators to be
used to save cost and EMI. The PICDEM™ USB hardware has the provisions
for a canned oscillator, a crystal, or resonators. Refer to Figure 3.1.
OSC2
6 MHz
EC
E4
HS
H4
OSC1
4x PLL
EC
E4
HS
H4
24 MHz
FINT
Q Clock
Generator
To PIC
To SIE
Figure 3.1: Oscillator/PLL Clock Control
3.1.1
Canned Oscillator
Any full size canned oscillator of 6 MHz or 24 MHz can be used. Remove the
resonator from the resonator pads to use the oscillator.
3.1.2
Resonator
A 6 MHz or 24 MHz resonator can be used. Pads are available to use resonators with internal or external capacitors. The resonator supplied with the kit is
a 6 MHz resonator with internal capacitors. If you decide to use a resonator
with external capacitors, you should select capacitors that will maximize the
voltage swing across the resonator.
2001 Microchip Technology Inc.
DS41174A-page 31
PICDEM™ USB User’s Guide
3.1.3
Crystal
A fundamental cut crystal of 6 MHz or 24 MHz can be used with additional
capacitors installed in the pads provided. The selection of external capacitors
must be chosen to maximize the voltage across the crystal.
3.2
Connector Pinout
This board was designed to provide experience with LS HID USB code. To
accommodate this goal, two popular interfaces have been selected to allow
for HID experimentation, the PS/2 and Gameport. A serial port was added,
but it cannot be used at baud rates below 4800 due to the high clock speed.
This prevents serial mice from being used. Additional support for LCD and
keypad was added to allow for the support of other popular devices.
3.2.1
Gameport (J4) Pinouts
The PC gameport is typically read through a one-shot multi-vibrator. This configuration uses capacitor charge timing to determine the joystick position. The
implementation for the PICDEM™ USB uses the analog converters to accomplish the same task. A 50K resistor is used to pull down each analog channel,
allowing the ADC to read voltages between 1.25V and 5V. This is not full
range, but it will allow joystick functions to work. Removing the pull-down
resistors will allow the full 5V range of the ADC to be used. Each button input
is pulled to 5V through a 1K resistor. Consult the schematic for additional
details.
1
9
2
10
3
11
4
12
5
13
6
14
7
15
8
D-sub female
8
15
7
14
6
13
4
12
4
11
3
10
2
9
1
D-sub male
Figure 3.2: Gameport Pinouts (J4)
DS41174A-page 32
2001 Microchip Technology Inc.
PICDEM™ USB Hardware
Table 3.1: D-sub 15 Female
3.2.2
Pin #
PIC Pin
Pin Function
1
VDD
VDD
2
RD0
Stick 1, Button 1
3
RA0
Stick 1, X axis
4
Vss
Ground
5
VSS
Ground
6
RA1
Stick 1, Y axis
7
RD1
Stick 1, Button 2
8
VDD
VDD
9
RD2
Stick 2, Button 2
10
RA2
Stick 2, Y axis
11
Vss
Ground
12
Vss
Ground
13
RA3
Stick 2, X axis
14
RD3
Stick 2, Button 1
15
VDD
VDD
PS/2 (J12) Pinouts
PS/2 interfaces are all the same, including the mouse and keyboard ports.
The interface is a device initiated synchronous serial port. This interface is
wired to RC0 and RC1, to allow CCP interrupts to be used to read the serial
data.
6
4
2
5
3
1
Note: This is the view of the Din6 female connector on the PICDEM™ USB.
Figure 3.3: PS/2 (J12) Pinouts
2001 Microchip Technology Inc.
DS41174A-page 33
PICDEM™ USB User’s Guide
Table 3.2: PS/2 (J12)
Pin #
PIC Pin
Pin Function
1
RC0
Data
3
VSS
Ground
4
VDD
+5V
5
RC1
Clock
2
No Connect
6
3.2.3
No Connect
RS-232 (J7) Pinouts
The RS-232 connector is a DCE device, just as in a PC. To connect to a PC, a
“null modem” device must be used (swap TX and RX). This allows standard
PC peripherals to be attached to the PICDEM™ USB without using any
special cables. Presumably the USB would be used for any communications
with the PC.
5
9
4
8
3
7
2
6
1
Figure 3.4: RS-232 (J7) Pinouts
Table 3.3: RS-232 (J7)
Pin #
PIC Pin
1
CD
2
RC7
RX
3
RC6
TX
4
5
DS41174A-page 34
Pin Function
DTR
Vss
GND
6
DSR
7
RTS
8
CTS
9
RI
2001 Microchip Technology Inc.
PICDEM™ USB Hardware
3.2.4
LCD (J1) Pinouts
The LCD connector provides support for a standard 14-pin LCD module.
These modules are available through many electronics supply houses. Any
module using a Hitachi 44780A controller should work.
This connector also provides access to the parallel slave port.
Table 3.4: J1 - LCD
Pin #
PIC pin
Pin Function
1
VSS
Ground
2
VDD
+5V
3
3.2.5
LCD Contrast
4
PE0 – RD
Register Select (H for data, L for instruction)
5
PE1 – WR
Read/Write (H for read, L for write)
6
PE2 – CS
Enable
7
PD0 – PSP0
Data 0
8
PD1 – PSP1
Data 1
9
PD2 – PSP2
Data 2
10
PD3 – PSP3
Data 3
11
PD4 – PSP4
Data 4
12
PD5 – PSP5
Data 5
13
PD6 – PSP6
Data 6
14
PD7 – PSP7
Data 7
Keypad (J10) Pinouts
The keypad connector is for attaching a HEX keypad. Any row/column
strobbed keypad, with at most 4 rows and columns should work. The pinout
was chosen to be compatible with most devices but you may have to make a
special cable.
Table 3.5: J10 - Keypad
2001 Microchip Technology Inc.
Pin #
PIC pin
Pin Function
1
PB0
Row Driver
2
PB1
Row Driver
3
PB2
Row Driver
4
PB3
Row Driver
5
PB4
Column Driver
6
PB5
Column Driver
7
PB6
Column Driver
8
PB7
Column Driver
9
No Connect
DS41174A-page 35
PICDEM™ USB User’s Guide
3.2.6
USB (J8) Pinouts
A standard USB Type B connector was used to allow a USB cable to connect
the PICDEM™ USB to the PC. This is against the USB specification. Technically, only full speed devices are allowed to use the type B connector.
Table 3.6: J8 - USB
Pin #
PIC pin
1
Power
2
D+
USB Signal D+
3
D-
USB Signal D-
4
3.3
Pin Function
Ground
Buttons and Jumpers
3.3.1
S1 - MCLR
Switch 1 is the MCLR line to the PIC16C745/765. This line resets the entire
system.
3.3.2
S2 - RA4
Switch 2 is connected to RA4. This is to allow a general purpose switch input
for code experiments. Debounce filtering is provided.
3.3.3
J3 - Bus/Self Power Selection
Jumper 3 switches the VDD power line from Bus power (VBUS from the USB
cable) to Self power (5V from the onboard regulator).
3.3.4
J9 - LED Enable
Some applications will want to use PORTB for some purpose other than driving the LED’s. By removing the jumper in J9, the LED’s will be disabled. The
default Chapter 9 firmware uses the LED’s to indicate activity at the different
stages of enumeration. To use this firmware mode, you should enable the
LED’s.
DS41174A-page 36
2001 Microchip Technology Inc.
PICDEM™ USB Hardware
3.4
Power
3.4.1
Self Power Options
A power supply is provided to run the PICDEM™ USB from a 9-20VAC/DC
power supply. A transformer is not supplied in the kit because every example
included will run from the bus power.
3.4.2
Bus Power
Most USB peripherals are powered from the 5V available from the USB cable.
A minimum of 100 mA is always available. In some situations, a maximum of
500 mA can be requested and used.
2001 Microchip Technology Inc.
DS41174A-page 37
PICDEM™ USB User’s Guide
NOTES:
DS41174A-page 38
2001 Microchip Technology Inc.
PICDEM™ USB User’s Guide
Chapter 4. Chapter 9 USB Firmware
4.1
Introducing the USB Software Interface
Microchip provides a layer of software for the PIC16C745/65, which handles
the lowest level interface. This software provides a simple Put/Get interface
for communication so your application won’t have to. Most of the USB processing takes place in the background through the Interrupt Service Routine.
From the application viewpoint, the enumeration process and data communication takes place without further interaction. However, substantial setup is
required in the form of generating appropriate descriptors.
Main Application
Put
EP1
Get
EP1
Init
USB
PICmicro MCU
USB
Figure 4.1: USB Software Interface
4.2
Integrating USB Into Your Application
The latest version of the USB interface software is available on Microchip’s
web site (http://www.microchip.com/).
The interface to the application is packaged in five functions: InitUSB,
PutEP1, PutEP2, GetEP1, and GetEP2. InitUSB initializes the USB peripheral, allowing the host to enumerate the device. Then, for normal data communications, the PutEPn functions send data to the host and GetEPn
functions receive data from the host.
Note:
Wherever the command names PutEPn and GetEPn are used, ’n’
represents the endpoint number.
Since the USB depends heavily on the descriptors, a bit of setup work must
be completed. The descriptors are the software parameters which communicate to the host what the device is and how to communicate with it. See USB
V1.1 Spec., Section 9.5 for more details.
2001 Microchip Technology Inc.
DS41174A-page 39
PICDEM™ USB User’s Guide
InitUSB enables the USB interrupt so enumeration can begin. The actual
enumeration process occurs in the background, driven by the host and Interrupt Service Routine. Macro ConfiguredUSB waits until the device is in the
CONFIGURED state. The time required to enumerate is completely dependent on the host and bus loading.
4.3
Interrupt Structure Concerns
4.3.1
Processor Resources
Most of the USB processing occurs via the interrupt and thus, is invisible to
the application. However, it still consumes processor resources. These
include ROM, RAM, Common RAM, Stack Levels, and Processor Cycles.
This section attempts to quantify the impact on each of these resources and
shows ways to avoid conflicts.
These considerations should be taken into account if you write your own Interrupt Service Routine: Save W, STATUS, FSR, and PCLATH, which are the file
registers that may be corrupted by servicing the USB interrupt.
The file usb_main.asm provides a skeleton ISR, which does this for you, and
includes tests for each of the possible ISR bits. This provides a good starting
point if you haven’t already written your own.
4.3.2
Stack Levels
The hardware stack on the PICmicro MCU is only eight levels deep. Therefore, the worst case call between the application and ISR can only be eight
levels. The enumeration process requires four levels, so it’s best if the main
application inhibits processing until enumeration is complete. ConfiguredUSB is a macro that waits until the enumeration process is complete for
exactly this purpose. This macro does this by testing the lower two bits of
USWSTAT (0x197).
4.3.3
ROM
The code required to support the USB interrupt, including Chapter 9 interface
calls, but excluding the descriptor tables is about 1 kW. The descriptor and
string descriptor tables can each require an additional 256W. The location of
these descriptors is not restricted, and the linker script may be edited to control the placement of each descriptor’s part. See the Strings and Descriptors
sections in the linker script.
4.3.4
RAM
With the exception of Common RAM discussed below, servicing the USB
interrupt requires ~40 bytes of RAM in Bank 2. This leaves all the General
Purpose RAM in Bank 0 and Bank 1, while leaving half of Bank 2 available for
your application.
DS41174A-page 40
2001 Microchip Technology Inc.
Chapter 9 USB Firmware
4.3.5
Common RAM Usage
The PIC16C745/765 has 16 bytes of common RAM. They are the last 16
addresses in each bank and all refer to the same 16 bytes of memory, without
regard to which register bank is currently addressed by the RP0, RP1 and IRP
bits.
They are particularly useful when responding to interrupts. When an interrupt
occurs, the ISR doesn’t immediately know which bank is addressed. With
devices that don’t support common RAM, the W register must be provided for
in each bank. The PIC16C745/765 can save the appropriate registers in Common RAM and not have to waste a byte in each bank for the W register.
4.3.6
Buffer Allocation
The PIC16C745/765 has 64 bytes of Dual Port RAM. Twenty-four bytes are
used for the Buffer Descriptor Table (BDT), leaving 40 bytes for buffers.
Endpoint 0 (EP0) IN and OUT need dedicated buffers, since a setup transaction can never be NAKed. That leaves three buffers for four possible endpoints. However, the USB Spec. requires that low speed devices are only
allowed 2 endpoints (USB V1.1, paragraph 5.3.1.2), where an endpoint is a
simplex connection that is defined by the combination of endpoint number and
direction.
The default configuration allocates individual buffers to EP0 OUT, EP0 IN,
EP1 OUT, and EP1 IN. The last buffer is shared between EP2 IN and EP2
OUT. Again, the USB Spec. states that low speed devices can only use two
endpoints beyond EP0. This configuration supports most of the possible combinations of endpoints (EP1 OUT and EP1 IN, EP1 OUT and EP2 IN, EP1
OUT and EP2 OUT, EP1 IN and EP2 OUT, EP1 IN and EP2 IN). The only
combination that is not supported by this configuration is EP2 IN and EP2
OUT. If your application needs both EP2 IN and EP2 OUT, the function
USBReset will need to be edited to give each of these endpoints dedicated
buffers at the expense of EP1.
4.4
File Packaging
The software interface is packaged into four files, designed to simplify the
integration with your application.
File usb_ch9.asm contains the interface and core functions needed to enumerate the bus. File descript.asm contains the device, configuration, interface, endpoint, and string descriptors. Both of these files must be linked in
with your application.
2001 Microchip Technology Inc.
DS41174A-page 41
PICDEM™ USB User’s Guide
File hidclass.asm provides some HID Class specific functions. Currently,
only Get_Report_Descriptor is supported. Other class specific functions can
be implemented in a similar fashion. When a get token interrupt determines
that it’s a class specific command on the basis that ReportType bit 6 is set,
control is passed to function ClassSpecific. If you’re working with a different
class, this is your interface between the core functions and the class specific
functions.
File usb_main.asm is useful as a starting point on a new application, and as
an example of how an existing application needs to service the USB interrupt
and communicate with the core functions.
4.5
Function Call Reference
Interface between the Application and Protocol layer takes place in three main
functions: InitUSB, PutEPn, and GetEPn (with ’n’ representing the endpoint
number).
4.5.1
Application Layer Function
4.5.1.1
InitUSB
InitUSB should be called by the main program immediately upon power-up. It
enables the USB peripheral and the USB Reset interrupt, and transitions the
part to the powered state to prepare the device for enumeration. At this point,
the USB Reset is the only USB interrupt allowed, preventing the part from
responding to anything on the bus until it’s been reset. The USB Reset interrupt initializes the Buffer Descriptor Table (BDT) and transitions the part to the
default state, where it responds to commands on address zero. When it
receives a Set Address command, the device transitions to the addressed
state and now responds to commands on the new address.
4.5.1.2
PutEPn
PutEPn (Buffer pointer, Buffer size) sends data to the host. The pointer to the
block of data to transmit is in the FSR/IRP, and the block is passed in the W
register. The endpoint is set with a Set Instruction preceding the function definition. If the IN buffer is available for that endpoint, the block of data is copied
to the buffer. The Data 0/1 bit is then flipped and the OWNS bit is set. A
"Buffer Not Available" will occur when it has been previously loaded and the
host has not requested that the USB peripheral transmit it. In this case, a
failure code would be returned so the application can try again later.
DS41174A-page 42
2001 Microchip Technology Inc.
Chapter 9 USB Firmware
4.5.1.3
GetEPn
GetEPn (Buffer Pointer) returns data sent from the host. Provided with a
buffer pointer in FSR/IRP, if there is a buffer available (data has been received
from the host), the data it is copied to the destination pointed to by FSR/IRP.
The endpoint is set with a set instruction preceding the function definition. If
no data is available, it returns a failure code. Thus, the functions of polling for
buffer ready and copying the data are combined into one function.
4.5.2
Protocol Layer Functions
4.5.2.1
ServiceUSBlnt
ServiceUSBlnt handles all interrupts generated by the USB peripheral. First,
it copies the active buffer to common RAM, which provides a quick turnaround on the buffer in dual port RAM. It also avoids having to switch banks
during processing of the buffer.
4.5.2.2
StallUSBEP/UnstallUSBEP
StallUSBEP/UnstallUSBEP sets or clears the STALL bit in the endpoint control register. The STALL bit indicates to the host that user intervention is
required and until such intervention is made, further attempts to communicate
with the endpoint will not be successful. Once the user intervention has been
made, UnstallUSBEP will clear the bit, allowing communications to take
place. These calls are useful in signaling the host that user intervention is
required. An example of this might be a printer out of paper.
4.5.2.3
SoftDetachUSB
SoftDetachUSB clears the DEV_ATT bit, electrically disconnecting the device
from the bus, then reconnecting so it can be re-enumerated by the host. This
process takes approximately 50 ms, to ensure that the host has seen the
device disconnect and re-attach to the bus.
4.5.2.4
CheckSleep
CheckSleep tests the UCTRL.UIDLE bit if set, indicating that there has been
no activity on the bus for 3 ms. If set, the device can be put to SLEEP, which
puts the part into a Low Power Standby mode until awakened by bus activity.
This has to be handled outside the ISR because we need the interrupt to
wake us from SLEEP, and because the application may not be ready to
SLEEP when the interrupt occurs. Instead, the application should periodically
call this function to poll the bit when the device is in a good place to SLEEP.
2001 Microchip Technology Inc.
DS41174A-page 43
PICDEM™ USB User’s Guide
Prior to putting the device to SLEEP, CheckSleep enables the activity interrupt so the device will be awakened by the first transition on the bus. The
PICmicro MCU will immediately jump to the ISR, which recognizes the activity
interrupt and then disables the interrupt and resumes processing with the
instruction following the CheckSleep call.
4.5.2.5
ConfiguredUSB
ConfiguredUSB (Macro) continuously polls the enumeration status bits and
waits until the host has configured the device. This should be used after the
call to InitUSB and prior to the first time your application attempts to communicate on the bus.
4.5.2.6
SetConfiguration
SetConfiguration is a callback function that allows your application to associate some meaning to a Set Configuration command from the host. The Chapter 9 software stores the value in USB_Curr_Config so it can be reported back
on a Get Configuration call. This function is also called passing the new configuration into W. This function is called from within the ISR so it should be
kept as short as possible.
4.6
Behind the Scenes
4.6.1
InitUSB
InitUSB clears the error counters and enables the 3.3V regulator and the
USB Reset interrupt. This implements the requirement to prevent the
PICmicro MCU from responding to commands until the device has been
RESET.
The host sees the device and resets the device to begin the enumeration process. The RESET then initializes the Buffer Descriptor Table (BDT) and EndPoint Control Registers, in addition to enabling the remaining USB interrupt
sources.
The interrupt transfers control to the interrupt vector (address 0x0004). Any
Interrupt Service Routine must preserve the processor state by saving the
FSR’s that might change during interrupt processing. We recommend saving
W, STATUS, PCLATH, and FSR. W can be stored in Common RAM to avoid
banking issues. Then, the Interrupt Service Routine starts polling the interrupt
flags to see what triggered the interrupt. The USB interrupts are serviced by
calling ServiceUSBInt, which further tests the USB interrupt sources to determine how to process the interrupt.
DS41174A-page 44
2001 Microchip Technology Inc.
Chapter 9 USB Firmware
Subsequently, the host sends a setup token requesting the device descriptor.
The USB Peripheral receives the Setup transaction, places the data portion in
the EP0 out buffer, loads the USTAT register to indicate which endpoint
received the data, and triggers the Token Done (TOK_DNE) interrupt. The
Chapter 9 commands interpret the Setup token and sets up the data to
respond to the request in the EP0 IN buffer. It then sets the UOWN bit to tell
the SIE there is data available.
Next, the host sends an IN transaction to receive the data from the setup
transaction. The SIE sends the data from the EP0 IN buffer and next sets the
Token Done interrupt to notify us that the data has been sent. If there is additional data, the next buffer full is set up in the EP0 IN buffer.
Token processing takes place for the entire enumeration sequence. The
device starts in the powered state, transitions to RESET via the Reset interrupt, moves to ADDRESSED via the Set Address command, and shifts to
CONFIGURED via a Set Configuration command.
The USB peripheral detects several different errors and handles most internally. The USB_ERR interrupt notifies the PIC that an error has occurred. No
action is required by the PICmicro MCU when an error occurs. Instead, the
errors are simply acknowledged and counted. There is no mechanism to pull
the device off the bus if there are too many errors. If this behavior is desired, it
must be implemented in the application.
The Activity interrupt is left disabled until the USB peripheral detects no bus
activity for 3 ms. Then, it suspends the USB peripheral and enables the Activity interrupt. The Activity interrupt subsequently re-activates the USB peripheral when bus activity resumes, so processing may continue.
4.6.2
CheckSleep
CheckSleep is a separate call that takes the bus idle one step further and
puts the PICmicro MCU to SLEEP if the USB peripheral has detected no
activity on the bus. This powers down most of the device to minimal current
draw. This call should be made at a point in the main loop where all other
processing is complete.
4.7
Examples
This example shows how the USB functions are used. This example first initializes the USB peripheral, which allows the host to enumerate the device.
The enumeration process occurs in the background, via an Interrupt Service
Routine. This function waits until enumeration is complete. Then, it polls EP1
OUT to see if there is any data available. When a buffer is available, it is copied to the IN buffer. Presumably, your application would be more interesting
than Example 4.1.
2001 Microchip Technology Inc.
DS41174A-page 45
PICDEM™ USB User’s Guide
Example 4.1: USB Peripheral Demo Program
; ******************************************************************
; Demo program that initializes the USB peripheral, allows the Host
;
to Enumerate, then copies buffers from EP1OUT to EP1IN.
; ******************************************************************
Main
pagesel
InitUSB
call
InitUSB
; Set up everything so we can enumerate
pagesel
Main
ConfiguredUSB
; wait here until we have enumerated.
CheckEP1
bankisel
pagesel
movlw
movwf
call
pagesel
btfss
goto
BUFFER
GetEP1
BUFFER
FSR
GetEP1
CheckEP1
STATUS,C
CheckEP1
PutBuffer
bankisel
pagesel
movlw
movwf
movlw
call
pagesel
btfss
goto
pagesel
goto
BUFFER
PutEP1
BUFFER
FSR
0x08
PutEP1
PutBuffer
STATUS,C
PutBuffer
CheckEP1
CheckEP1
; Check Endpoint 1 for an OUT transaction
; point to lower banks
; point FSR to our buffer
; If data is ready, it will be copied.
; was there any data for us?
; Nope, check again.
; point to lower banks
; point FSR to our buffer
; send 8 bytes to endpoint 1
; was it successful?
; No: try again until successful
; Yes: restart loop
end
4.8
Multiple Configuration or Report Descriptors
The Ch9 firmware makes allowances for the fact that more than one configuration or report descriptor may be desired. Allowances for multiple interface,
HID, and endpoint descriptors were not made, because they are not needed.
These descriptors are all read in with the configuration descriptor, regardless
of how many there are.
DS41174A-page 46
2001 Microchip Technology Inc.
Chapter 9 USB Firmware
The host requests the descriptors by specifying the type of descriptor it wants
and an index value. If more than one configuration descriptor exists, it will
request the first one by specifying an index of zero and the second, by specifying an index of one. To make this process as easy as possible for developers, the functions Config_descr_index and Report_descr_index have been
created in descript.asm. These functions will need to be modified if your
code has more than one configuration, or more than one report descriptor. All
you need to do is specify the starting label for additional descriptors in the
lookup table for these functions.
Note:
4.9
String descriptors also use an index function, string_index (in
descript.asm). This function will need to be modified in the
same manner if your code has a number of strings other than six.
Optimizing the Firmware
This firmware has been created to provide developers with ready-made USB
functions, so they don’t have to create these functions for themselves. Most
developers will not utilize all of the functions in the Ch9 firmware. In order to
optimize the program memory, unused functions can be taken out of the firmware. The following guidelines are a good place to start the optimization.
4.9.1
USB Status on PORTB
The firmware outputs the status of USB communication on PORTB. This feature is intended for use with the PICDEM™ USB circuit board, which drives an
LED with each PORTB pin. The LEDs indicate the following USB status information: RB0 – powered, RB1 – default, RB2 – addressed, RB3 – configured,
RB4 – sleeping, RB5 – EP0 active, RB6 – EP1 active, RB7 – EP2 active.
Obviously, these USB status indicators will probably not be used in a finished
product by a developer, although they are very helpful during development. All
code associated with the USB status LEDs can be eliminated from the program memory by ensuring that SHOW_ENUM_STATUS is not defined at the
top of usb_ch9.asm.
4.9.2
Error Counter
Similar to the USB status LEDs, code exists in the firmware that counts various errors for debugging purposes. Program memory space can be saved by
making sure that COUNTERRORS is not defined.
4.9.3
GetEP1, GetEP2, PutEP1, and PutEP2
These functions are all macros defined in usb_defs.inc. Instances of each
of these macros occur in usb_ch9.asm. If a developer does not utilize one or
more of these functions, space can be saved by removing the instance(s) not
needed from usb_ch9.asm.
2001 Microchip Technology Inc.
DS41174A-page 47
PICDEM™ USB User’s Guide
4.9.4
HID Class
The HID class is one of several classes suitable for low speed USB. In addition to these other classes, a vendor-defined class can be specified. Should a
developer use a class other than the HID class, any HID class specific code in
the firmware would be wasting space. The HID class specific code is found in
the file hidclass.asm. In a case where the HID class is not being utilized by
a developer, this file and any variables or labels associated with it, should be
removed from the project.
4.10 Cursor Demonstration
Microchip provides a working USB demonstration. This demonstration has the
effect of moving the cursor in a small circle on the user’s screen. The
following steps will get the demonstration working with an actual part or the
MPLAB ICE.
4.10.1
Getting the USB Demonstration to Work on a
PIC16C745/65
1.
Note:
2.
3.
Note:
4.
5.
DS41174A-page 48
Unzip usbxxxasm.zip to a project folder.
In the file name usbxxxasm.zip, xxx is the version number and
may change without notice.
Build the project in MPLAB IDE.
Program a PIC16C745 using a PICSTART Plus or a
PRO MATE II programmer. Make sure the configuration bits are
set as follows:
•
Oscillator:
H4
•
Watchdog Timer:
Off
•
Power-up Timer:
Off
•
Code Protect:
Off
To program a PIC16C765, you will need to use the linker file and
include files associated with the PIC16C765. In addition, you will
need to identify the part in the Development mode dialog. See the
MPLAB IDE User’s Guide for details.
Appendix A details the circuit in which to implement the
PICmicro MCU. Attach the USB cable to your computer.
Provide power to the PICmicro MCU. If you are running Windows 98 (with the USB upgrade), Windows NT, or Windows
2000, your operating system will detect a new device and install
the necessary drivers automatically. After this occurs, you
should see the cursor rotating in a small circle on your screen.
To stop the cursor from rotating, detach the USB cable.
2001 Microchip Technology Inc.
Chapter 9 USB Firmware
4.10.2
Getting the USB Demonstration to Work Using the
MPLAB ICE
1.
Note:
2.
3.
Note:
4.
5.
2001 Microchip Technology Inc.
Unzip usbxxxasm.zip to a project folder.
In the file name usbxxxasm.zip, xxx is the version number and
may change without notice.
Build the project in MPLAB IDE.
Make sure the emulator is set up in the Development Mode
dialog, as follows:
•
Tools:
MPLAB ICE Emulator
•
Clock: Desired Frequency:
24 MHz
•
Configuration: Watchdog Timer:
None
•
Power: Processor Power:
From Target Board
The firmware is set up to run on a PIC16C745 as the default. To
emulate a PIC16C765, you will need to use the linker file and
include files associated with the PIC16C765. In addition, you will
need to identify the part in the Development Mode dialog.
Appendix A illustrates the circuit in which to implement the
MPLAB ICE. Connect the USB cable to your computer. The
external oscillator portion of the circuit is optional when using
MPLAB ICE.
Run the project on the emulator. If you are running Windows 98
(with the USB upgrade), Windows® NT, or Windows® 2000, your
operating system will detect a new device and install the necessary drivers automatically. After this occurs, you should see the
cursor rotating in a small circle on your screen. To stop the cursor from rotating, press F5.
DS41174A-page 49
PICDEM™ USB User’s Guide
4.10.3
Emulation Tips
1.
2.
3.
4.
Note:
DS41174A-page 50
Turn on the emulator. Open the project to initialize the emulator.
If the project is in a mode other than Emulation, follow step 2.
If your project is already open before you turn the emulator on,
you can initialize it by first, turning the emulator on. Then, go to
the option menu and click Development Mode. Make sure that
the MPLAB ICE Emulator radio button is selected in the Tools
folder of the Development Mode dialog. Click OK. The emulator
will initialize.
Be certain the proper processor module and device adapters
are installed.
Should you have other problems, please refer to the MPLAB
ICE Users Guide as your first resource.
Be sure to pull D- up to VUSB (via R1) not VDD. For more on why
this is done, see the section Universal Serial Bus: Transceiver,
Regulator in the PIC16C745/765 data sheet.
2001 Microchip Technology Inc.
PICDEM™ USB User’s Guide
Chapter 5. Troubleshooting
5.1
Introduction
This chapter describes some common problems associated with using
PICDEM™ USB and steps to follow to resolve those problems. It also
includes frequently asked questions (FAQ’s) associated with using PICDEM™
USB.
5.2
Highlights
Highlights covered in this chapter:
• Common Problems
• FAQ’s
5.3
FAQ
5.3.1
Hardware Questions
Q: Should I connect VBUS to VUSB?
A: NO, these are completely different voltages. VUSB is a 3.3V power supply,
intended to source power to pull-up resistors on D+ or D-. VBUS is a 5V power
supply, intended to power the entire circuit board.
Q: Ok, but can I leave the 220 nF capacitor off of VUSB?
A: NO, this capacitor is required to stabilize the VUSB voltage. Make sure you
copy the circuit as drawn in the data book.
5.3.2
PC/Windows Questions
Q: When I made a descriptor change, why is Windows still showing my
old description?
A: Windows stores most of the descriptor information in the registry. It then
makes the assumption that devices with the same vendor and product ID
have the same descriptor and will load the old descriptor from the registry.
This may be fine for consumers, but engineers require different behavior.
Before you enumerate with a new registry, simply use regedit to delete all
old entries about your device from the registry. If this is slowing you down, use
a Macintosh to develop the device descriptors and then switch to Windows to
develop the actual application code. The Macintosh does not have a permanent device registry and rereads all the information every time.
2001 Microchip Technology Inc.
DS41174A-page 51
PICDEM™ USB User’s Guide
5.3.3
Macintosh Questions
Q: Where do I go to get example code for Macintosh systems?
A: Going to www.apple.com/usb is a good start.
Q: Why doesn’t the keyboard example work on my Macintosh?
A: You are using a version earlier than MacOS 10.0. The SetIdle and GetIdle
are required for versions earlier than MacOS 10.0. These functions are not
implemented yet.
DS41174A-page 52
2001 Microchip Technology Inc.
PICDEM™ USB User’s Guide
Appendix A. PICDEM™ USB Schematics
A.1
Introduction
This appendix contains schematics associated with PICDEM™ USB.
A.2
Highlights
Topics covered in this appendix:
• PC Peripheral Connectors
• LCD, LED and ICD Connections
• PIC16C745 and Expansion Connector
• PIC16C765 and Oscillator
• Power Supply and USB Connections
• Parts Placement Diagram
2001 Microchip Technology Inc.
DS41174A-page 53
PICDEM™ USB User’s Guide
Schematics
V- 6
C2+ 4
1µF
RC6
RC7
5
RA1
RD1
Stick 2 Button 1
Stick 2 X axis
RD2
Stick 2 Y axis
Stick 2 Button 2
RA3
RD3
RA2
RB3
4
RB4
3
4
5
13
12
5
6
6
11
7
10
7
RB7
8
9
8
9
9
8
RN4
7
2
6
1
PC Style Gameport
R16
Stick 1 Y axis
Stick 1 Button 2
15
14
2
3
DB9M
VDD
RD0
RA0
2
RB2
RB6
MAX232CPE
Stick 1 Button 1
Stick 1 X axis
RB1
RB5
3
13
8
1
J7
4
14
7
16
RS-232
5
3 C1C211
T1IN T1OUT
10 T2IN T2OUT
12 R1OUT R1IN
9 R2OUT R2IN
RB0
1
HDR-1X9
C19
VCC
C1+
J10
RN1 470 typ.
1µF
16
1
C18
GND 15
1µF
2 V+
C17
1µF
VDD
C16
A.3
DB15F
100
15
S282
14
S2Y
13
12
S2X
11
S281
10
9
8
S1B2
7
S1Y
6
5
4
S1X
3
S1B1
2
1
R15
R14
R13
R12
R11
R10
R6
VDD
J12
6
5
4
3
2
1
RC0 PS-2 Clock
RC1 PS-2 Data
CONN-MDIN6PRA
PS-2 Keyboard/Mouse Interface
J4
GND
1
VDD
TP2
C5
.1µF
C6
.1µF
C7
.1µF
C13
.1µF
R4
S1B1
S1B2
S281
S282
1
2
3
4
5
6
1K
51K
C14
.1µF
C15
.1µF
C21
.1µF
C22
.1µF
S2Y
S2X
S1Y
S1X
6
5
4
3
2
1
R5
Figure A.1: PC Peripheral Connectors
DS41174A-page 54
2001 Microchip Technology Inc.
PICDEM™ USB Schematics
RN2:A
ICD (future expansion)
RED
RB0
J6
VDD
MCLR
1
RB7
1
3
1
4
1
5
1
6
1
7
1
8
1
9
1
RB1
4
5
D4
RJ11_6PIN
3
RB6
2
D3
2
RB3
470
RB2
D5
RB3
6
D6
RB4
D7
RB5
D8
RB6
D9
RB7
D10
2
VDD
VDD
GND 1 VSS
VDD
2
3
R21
150
RE0
RE1
4
5
18
K
17
GND GND
K
16
A
A
15
10Ω
LCD1
DB7
VCC
DB6
VEE
DB5
RS
R/W
1
J9
R3
LCD_DISPLAY
DB4
DB3
14
13
12
11
10
RD7
RD6
RD5
RD4
RD3
RE2 6 E
DB2
9 RD2
RD0 7 DB0
DB1
8 RD1
GND
Figure A.2: LCD, LED and ICD Connections
2001 Microchip Technology Inc.
DS41174A-page 55
PICDEM™ USB User’s Guide
J5:1
VDD
C11
20
0.1µF
MCLR
RA0
RB7
RA1
RB6
RA2
RB5
RA3
RB4
RA4
RB3
RA5
RB2
RE0
RB1
RE1
RB0
RE2
U3
MCLR
RA0
RA1
RA2
RA3
RA4
RA5
1
2
3
4
5
6
7
VDD
RB0 21
RB0
RB1 22
RB1
RB2 23
RB2
RA0
RB3 24
RB3
RA1
RB4 25
RB4
RA2
RB5 26
RB5
RA3
RB6 27
RB6
RA4
RB7 28
RB7
RC0 11
RC0
12
RC1
RC2 13
RC2
17
RC6
MCLR
RA5
RC1
OSC1
9
OSC1
RC6
18
RC7
VUSB 14
VUSB
RC7
OSC2
10
8
19
IDC2X20M
J5:2
DD+
VSS
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
RC7
RD7
RC6
RD6
OSC2
VSS
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
RD5
15
D-
RD4
16
D+
RD3
RC2
RD2
RC1
RD1
RC0
RD0
PIC16C745 28-PDIP
VDD
IDC2X20M
Figure A.3: PIC16C745 and Expansion Connector
DS41174A-page 56
2001 Microchip Technology Inc.
PICDEM™ USB Schematics
VDD
VDD
VDD
RE2/CS/AN7 10
9
RE1/WR/AN6
8
RE0/RD/AN5
11 VDD
32 VDD
4.7k
R8
4.7k
R23
U5
S1
R9
1
4
2
3
MCLR
RA0
RA1
RA2
S2
RA3
R24
4
RA4
2
3
RA5
470
RB0
RB1
RB2
Y3
1 NC/OE
2 GND
VCC
OUT
4
3
VDD
RB3
RB4
OSC1
RB5
RB6
OSC_CAN
RD7
2 RA0/AN0
3 RA1/AN1
RD6/PSP6 29
RD5/PSP5 28
RD6
4 RA2/AN2
5 RA3/AN3/VREF
RD4/PSP4 27
22
RD3/PSP3
21
RD2/PSP2
RD4
RD1/PSP1 20
RD0/PSP0 19
RD1
RC7/RX/DT 26
RC6/TX/CK 25
RC7
RC2/CCP1 17
RC1/T1OSI/CCP2 16
RC2
RC0/T1OSO/T1CKI 15
RC0
6 RA4/T0CKI
7 RA5/AN4
RB7
33 RB0/INT
34 RB1
35 RB2
36 RB3
37 RB4
38 RB5
39 RB6
40 RB7
D+ 24
D- 23
C1
VDD
OSC1
0.1µF
6 MHz
13
VUSB
VSS
OSC2/CLKOUT
OSC2
14
C2
18
RD5
RD3
RD2
RD0
RC6
RC1
D+
DVUSB
OSC1/CLKIN
Y4
C3
RE0
RD7/PSP7 30
C10
0.1µF
B3F-1000
C20
0.1µF
1
RE1
1 MCLR/VPP
470
B3F-1000
RE2
VSS
12
31
PIC16C765
33pF
33pF
RESONATOR-ZTT
Figure A.4: PIC16C765 and Oscillator
2001 Microchip Technology Inc.
DS41174A-page 57
PICDEM™ USB User’s Guide
VBUS
1
1.5k
D-
2
VUSB
R1
D+
3
1.5k
R2
Full speed future
expansion
4
J2
1
3
CR1
2
C8
C9
+
0.1µF
10µF
3
470
VBUS
R7
2
OUT
IN
1
2
3
1
COM
U2
LM7805
J3
VDD
+
C12
W02M
47µF
DJ005B
D2
Green
3PHDR
Self/Bus Power
Figure A.5: Power Supply and USB Connections
DS41174A-page 58
2001 Microchip Technology Inc.
J12
J4
2001 Microchip Technology Inc.
RA4
LED Enable
+
+
+
+
ICD
Future Use
C9
D2
CR1
Y4
C1
+
9-20v
AC/DC
C12
J3
J2
Self
U5
RB7
RB6
+
C8
R7
U2
R11
R10
R14
R15
D10
Bus
U3
RN1
EP2 - Act.
D9
PIC16C765
J6
PICDEM USB
C2
C6 C7 C5 C13
C3
C22
R12 R13 R6 R16
C15
Y3
C21
RB4
RB3
R5
D8
D6
RB5
EP0 - Act.
D7
Configured
J10
Keypad
TP3
PIC16C745
C19
C16
C17
U4
R4
C18
S1
RB2
D5
C10 C20 C14
R8 R9R24 R23
MCLR
Gameport
S2
D4
Default
RB0 J9 RB1
D3
USB Communication Status (Port B)
Addressed
Sleeping
EP1 - Act.
RN2
Powered
C4
RD7
RD6
RD5
RD4
RD3
RD2
RD1
RD0
VDD
GND
RA0 TP1
RA1 VDD
RA2 GND
RA3 TP2
RA4
RA5
RE0
RE1
RE2
J8 USB
R2
R1
Full Speed Pull-up
TP4
RC2
RC1
RC0
VDD
GND
RC7
RC6
MCLR
RB7
RB6
RB5
RB4
RB3
C11RB2
RB1
RB0
R22
V+
LCD Backlight Power
GND
R3
Prototyping Area
R21
LCD Module
PICDEM™ USB Schematics
+
PS-2
Figure A.6: Parts Placement Diagram
DS41174A-page 59
PICDEM™ USB User’s Guide
NOTES:
DS41174A-page 60
2001 Microchip Technology Inc.
PICDEM™ USB User’s Guide
Appendix B. PS/2 Lookup Tables
B.1
Introduction
This appendix contains tables identifying command and scan codes associated with PICDEM™ USB.
B.2
Scan Codes
Table B-1: PS/2 Keycodes
2001 Microchip Technology Inc.
Key
Make
Break
Key
Make
A
1C
F0,1C
9
46
B
32
F0,32
`
0E
C
21
F0,21
-
4E
D
23
F0,23
=
55
E
24
F0,24
\
F
2B
F0,2B
BKSP
G
34
F0,34
SPACE 29
Break
Key
Make
Break
F0,46
[
54
F0,0E
INSERT E0,70
E0,F0,70
F0,4E
HOME
E0,6C
E0,F0,6C
F0,55
PG UP
E0,7D
E0,F0,7D
5D
F0,5D
DELETE E0,71
E0,F0,71
66
F0,6
END
E0,69
E0,F0,69
F0,29
PG DN
E0,7A
E0,F0,7A
F0,54
H
33
F0,33
TAB
0D
F0,0D
U ARROW E0,75
E0,F0,75
I
43
F0,43
CAPS
58
F0,58
L ARROW E0,6B
E0,F0,6B
J
3B
F0,3B
L SHFT 12
F0,12
D ARROW E0,72
E0,F0,72
K
42
F0,42
L CTRL 14
F0,14
R ARROW E0,74
E0,F0,74
L
4B
F0,4B
L WIN E0,1F
E0,F0,1F NUM
77
F0,77
M
3A
F0,3A
L ALT 11
F0,11
KP /
E0,4A
F0,4A
N
31
F0,31
R SHFT 59
F0,59
KP *
7C
F0,7C
O
44
F0,44
R CTRL E0,14
E0,F0,14 KP -
7B
F0,7B
P
4D
F0,4D
R WIN E0,27
E0,F0,27 KP +
79
F0,79
Q
15
F0,15
R ALT E0,11
E0,F0,11 KP EN
E0,5A
F0,5A
R
2D
F0,2D
APPS
E0,F0,2F KP .
71
F0,71
S
1B
F0,1B
ENTER 5A
F0,5A
KP 0
70
F0,70
T
2C
F0,2C
ESC
76
F0,76
KP 1
69
F0,69
U
3C
F0,3C
F1
5
F0,05
KP 2
72
F0,72
V
2A
F0,2A
F2
6
F0,06
KP 3
7A
F0,7A
W
1D
F0,1D
F3
4
F0,04
KP 4
6B
F0,6B
X
22
F0,22
F4
0C
F0,0C
KP 5
73
F0,73
Y
35
F0,35
F5
3
F0,03
KP 6
74
F0,74
Z
1A
F0,1A
F6
0B
F0,0B
KP 7
6C
F0,6C
0
45
F0,45
F7
83
F0,83
KP 8
75
F0,75
1
16
F0,16
F8
0A
F0,0A
KP 9
7D
F0,7D
2
1E
F0,1E
F9
1
F0,01
]
5B
F0,5B
3
26
F0,26
F10
9
F0,09
;
4C
F0,4C
4
25
F0,25
F11
78
F0,78
'
52
F0,52
5
2E
F0,2E
F12
7
F0,07
,
41
F0,41
6
36
F0,36
.
49
F0,49
7
3D
F0,3D
/
4A
F0,4A
8
3E
F0,3E
E1,14,77
E1,F0,14
PAUSE F0,77
NONE
SCROLL 7E
F0,7E
E0,2F
PRNT
E0,12,
E0,F0,7C
SCRN
E0,7C
E0,F0,12
DS41174A-page 61
PICDEM™ USB User’s Guide
B.3
Command Codes
Table B-2: Host to PS/2 Keyboard Commands
DS41174A-page 62
HEX Code
Description
ED
Turns on/off LEDs -- Keyboard replies with ACK (FA) and waits
for another byte to be sent. Next byte sent determines the state
of the LEDs. (Bits 0-2 correspond to LEDs 1,2,3. Bits 3-7 should
always be 0.)
EE
Echo -- Keyboard should respond with Echo (EE).
F0
Set Scan Code Set -- Responds with ACK (FA) and waits for
another byte to be sent. Next byte sent will be either 01, 02, or
03 (corresponding to scan code sets 1, 2, and 3.) If 00 is sent
(instead of 01, 02, or 03), keyboard will respond with ACK (FA),
followed by the current scan code set (again, 01, 02, or 03).
F2
Get ID -- Responds with ACK (FA), followed by an ID (A3, AB).
This also enables scanning.
F3
Set repeat rate -- Keyboard replies with ACK (FA) and waits for
another byte to be sent. Next byte sent will determine the type of
automatic repeat rate for the keyboard. After this byte is sent,
keyboard responds with another ACK (FA).
F4
Enable keyboard -- Clear the buffer and start scanning for data;
replies with ACK (FA).
F5
Disable keyboard -- Disables scanning and replies with ACK
(FA). Does not affect indicator LEDs.
F6
Restore default values. Does not affect indicator LEDs.
F7
Set all keys typematic. Responds with ACK (FA).
F8
Set all keys make/break. Responds with ACK (FA).
F9
Set all keys make. Responds with ACK (FA).
FA
Set all keys typematic/make/break. Responds with ACK (FA).
FB
Set key type typematic.
FC
Set key type make/break.
FD
Set key type make.
FE
Resend -- Keyboard responds by retransmitting the last
command it sent.
FF
Reset -- Resets the keyboard.
2001 Microchip Technology Inc.
PS/2 Lookup Tables
Table B-3: PS/2 Keyboard to Host Commands
HEX Code
Description
00
Key detection error/keyboard buffer overflow (if sets 2 or 3 scan
codes are enabled).
83
ABKeyboard ID.
AA
Self-test passed.
EE
Echo -- Sent to Host after receiving "Echo" command from host.
FA
Acknowledge (ACK).
FC
Self-test failed.
FE
Resend -- Host responds by retransmitting the last command
sent.
FF
Key detection error/keyboard buffer overflow (if set 1 scan
codes are enabled).
Table B-4: PS/2 Mouse Commands
2001 Microchip Technology Inc.
HEX Code
Description
FF
Reset -- This command causes the mouse to enter the RESET
mode and do an internal Self-Reset.
FE
Resend -- Any time the mouse receives an invalid command, it
returns a resend command to the host system. The host system, in turn, sends this command when it detects any error in
any transmission from the mouse. When the mouse receives
the resend command, it retransmits the last packet of data sent.
F6
Set Default -- This command re-initializes all conditions to the
power-on default state.
F5
Disable -- This command is used in the Stream mode to stop
transmissions initiated by the mouse. The mouse responds to all
other commands while disabled. If the mouse is in the Stream
mode, it must be disabled before sending it any command that
requires a response.
F4
Enable -- This command is used in the Stream mode to begin
transmission.
"F3,XX"
Set sampling rate -- In the stream mode, this command sets the
sampling rate to the value indicated by byte XX (HEX)/sex.
F2
Read device type -- This command always receives a response
of 0x00 from the mouse.
F0
Set Remote mode -- Sets the mouse to Remote mode. Data values are reported on in response to a read data command.
EE
Set Wrap mode -- Sets the mouse to Wrap mode. The mode
remains until 0xFF or 0xEC is received.
EC
Reset Wrap mode -- The mouse returns to the previous mode of
operation after receiving this command.
DS41174A-page 63
PICDEM™ USB User’s Guide
Table B-4: PS/2 Mouse Commands (Continued)
DS41174A-page 64
HEX Code
Description
EB
Read data -- This command requests that all data defined in the
data packet format be transmitted. This command is executed in
either Remote or Stream mode. This data is transmitted even if
there has been no movement since the last report or the switch
status is unchanged.
EA
Set Stream mode -- This command sets the mouse to Stream
mode.
E9
Status request -- When this command is issued by the system,
the mouse responds with a 3-byte status report, same as Data
Report.
"E8,XX"
Set resolution -- The mouse provides 4 resolutions, selected by
the second byte of the command.
E7
Set scaling 2:1 -- Scaling is used to provide a course/fine tracking response. At the end of a sample interval in the stream
mode, the current X and Y data values are converted to new
values. The sign bits are not involved in the conversion. 2:1
scaling is performed only in Stream mode. In response to a read
data command, the current value before conversion is sent.
E6
Reset scaling -- This command restores scaling to 1:1.
2001 Microchip Technology Inc.
PICDEM™ USB USER’S GUIDE
Glossary
Introduction
This glossary provides a common frame of reference by defining the terms
that follow.
Highlights
This glossary contains:
• PICSTART Plus Terms
PICDEM™ USB Terms
Application
A set of software and hardware developed by the user, usually designed to be
a product controlled by a PICmicro microcontroller.
Assembler Source Code
A text file that is processed by an assembler to produce a one-to-one
correspondence between assembler instructions and PICmicro machine
code.
Assemble
To translate a user’s “ASM” source text code into machine code.
Breakpoint – Software
An address where execution of the firmware will HALT.
Breakpoint – Hardware
An event whose execution will cause a HALT.
Build
A function that recompiles all the source files for an application.
C Source Code
A program written in the high level language called “C,” and which will be
converted into PICmicro machine code.
Compile
To translate a user’s “C” source text code into machine code.
Configuration Bits
Unique bits programmed to set modes of operation. A configuration bit may or
may not be preprogrammed. For MPLAB ICE, these bits are set in the
Options>Processor Setup dialog.
2001 Microchip Technology Inc.
DS41174A-page 65
PICDEM™ USB User’s Guide
Data RAM
General purpose file registers from RAM on the PICmicro device being
emulated. The File Register window displays data RAM.
Download
Download is the process of sending data from the host PC to the emulator or
to the target board.
EEPROM
Electrically Erasable Programmable Read Only Memory. A special type of
PROM that can be erased electrically. Data is written or erased one byte at a
time. EEPROM retains its contents even when power is turned off.
Emulation
The process of executing software loaded into memory on the emulator
probe, as if the firmware resided on the microcontroller device under
development.
Emulation Memory
Program memory contained within the emulator.
Emulator
Hardware that performs emulation.
Emulator System
The Microchip Emulator System includes the MPLAB ICE Pod, processor
module, device adapter, cables and the MPLAB software.
Enumeration
Enumeration is the process of a device communicating its requirements to the
host and the host assigning a unique address to the device.
Event
A description of a bus cycle which may include address, data, pass count,
external input, cycle type (fetch, R/W) and time stamp.
Export
Send data out of MPLAB IDE in a standardized format.
Extended Microcontroller Mode (PIC17CXX Devices Only)
In Extended Microcontroller mode, on-chip program memory, as well as
external memory, are available. Execution automatically switches to external
if the program memory address is greater than the internal memory space of
the PIC17CXX device. Inaccessible memory in Extended Microcontroller
mode includes configuration bits, test memory, and boot memory.
External Input Line (MPLAB ICE 2000 Only)
An External Input Signal Logic Probe Line (TRIGIN) for setting an event
based upon external signals.
DS41174A-page 66
2001 Microchip Technology Inc.
Glossary
External RAM (PIC17CXX Devices Only)
Off-chip Read/Write memory.
File Registers
On-chip general purpose and special function registers.
FLASH
A type of EEPROM where data is written or erased in blocks instead of bytes.
FNOP
Forced No Operation. A forced NOP cycle is the second cycle of a two-cycle
instruction. Since the PICmicro architecture is pipelined, it pre-fetches the
next instruction in the physical address space while it is executing the current
instruction. However, if the current instruction changes the program counter,
this pre-fetched instruction is explicitly ignored, causing a forced NOP cycle.
HALT
The command that stops the emulator. Executing HALT is the same as
stopping at a break point. The program counter stops, and the user can
inspect and change register values, and single step through code.
HEX Code
A file of executable instructions assembled or compiled from source code into
standard HEX format code. HEX code can be directly converted to object
code.
High Level Language
A language for writing programs that is of a higher level of abstraction from
the processor than assembler code. High level languages (such as C) employ
a compiler to translate statements into machine instructions that the target
processor can execute.
ICE
In-Circuit Emulator. MPLAB ICE is Microchip’s In-Circuit Emulator that works
with MPLAB IDE.
IDE
Integrated Development Environment. An application that has multiple
functions for firmware development. The MPLAB IDE integrates a compiler,
an assembler, a project manager, an editor, a debugger, a simulator, and an
assortment of other tools within one Windows application. A user developing
an application should be able to write code, compile, debug and test an
application without leaving the MPLAB desktop.
Import
Bring data into the MPLAB Integrated Development Environment (IDE) from
an outside source
Mac
Short for Macintosh.
2001 Microchip Technology Inc.
DS41174A-page 67
PICDEM™ USB User’s Guide
MacOS
The Macintosh Operating System. Versions 8.6 and higher have USB
support.
Make Project
A command that rebuilds an application, recompiling only those source files
that have changed since the last complete compilation.
Microcontroller Mode
One of the possible program memory configurations of the PIC17CXX family
of microcontrollers. In Microcontroller mode, only internal execution is
allowed. Thus, only the on-chip program memory is available in
Microcontroller mode. Accessible memory includes: program memory,
configuration bits, test memory, and boot memory (FE00h to FFFFh).
Microprocessor Mode
One of the possible program memory configurations of the PIC17CXX family
of microcontrollers. In Microprocessor mode, the on-chip program memory is
not used. The entire 64K program memory is mapped externally. Inaccessible
memory in Microprocessor mode includes configuration bits, test memory,
and boot memory.
MPLAB ICE
Microchip’s in-circuit emulator that works with MPLAB IDE.
MPSIM
Microchip’s simulator that works with MPLAB IDE.
MPLAB Software
The name of the main executable program that supports the IDE with an
Editor, Project Manager, and Emulator/Simulator Debugger. The MPLAB
Software resides on the PC host. The executable file name is MPLAB.EXE.
MPLAB.EXE calls many other files.
MRU
Most Recently Used. Refers to files and windows available to be selected
from MPLAB main pull-down menus.
Non Real-Time
Refers to the processor executing single step instructions, or MPLAB IDE
being run in Simulator mode.
NOP
No operation.
DS41174A-page 68
2001 Microchip Technology Inc.
Glossary
Object Code
The machine code that is produced from the source code after it is processed
by an assembler or compiler. This code will be the memory resident code that
will run on the PICmicro MCU in the user’s application. Relocatable code is
code produced by MPASM Assembler or MPLAB C17, that can be run
through MPLINK Object Linker.
Off-Chip Memory
Off-Chip Memory refers to the memory selection option for the PIC17CXX
device, where memory may reside on the target board, or where all program
memory may be supplied by the emulator. Options > Processor Setup >
Hardware provides the Off-Chip Memory selection dialog box.
PC
Any IBM or compatible Personal Computer. MPLAB IDE needs a 486X or
better machine.
Host
The computer that is serving as master to a USB device. This could be any
machine with a USB interface, including PC’s or Mac’s.
PICmicro MCU
PICmicro MCU refers to the PIC12CXX, PIC14000, PIC16C5X, PIC16CXX,
PIC17CXX and PIC18CXX Microchip microcontroller families.
PICMASTER Emulator
The hardware unit that provides tools for emulating and debugging firmware
applications. This unit contains emulation memory, break point logic,
counters, timers, and a trace analyzer among some of its tools. MPLAB ICE is
the newest emulator from Microchip.
Pod
The external emulator box that contains emulation memory, trace memory,
event and cycle timers, and trace/break point logic. Occasionally used as an
abbreviated name for the MPLAB ICE Emulator.
Power-on Reset Emulation
A software randomization process that writes random values in data RAM
areas to simulate uninitialized values in RAM upon initial power application.
Program Counter
A register that specifies the current execution address for emulation and
simulation.
Program Memory
Memory containing the downloaded target application firmware.
Project
A set of source files and instructions to build the object code for an
application.
2001 Microchip Technology Inc.
DS41174A-page 69
PICDEM™ USB User’s Guide
PRO MATE II
A device programmer from Microchip. Can be used with MPLAB IDE or
stand-alone.
Prototype System
A term referring to a user's target application, or target board.
PWM Signals
Pulse Width Modulation Signals. Certain PICmicro devices have a PWM
peripheral.
Radix
The number base, hex, or decimal, used in selecting an address and for
entering data in the Window > Modify command.
Real-Time
When released from the HALT state, the processor runs in Real-Time mode
and behaves exactly as the normal chip would behave. In Real-Time mode,
the real-time trace buffer is enabled and constantly captures all selected
cycles, and all break logic is enabled. In the emulator, the processor executes
in real-time until a valid break point causes a HALT, or until the user halts the
emulator.
In the simulator, real-time simply means execution of the microcontroller
instructions as fast as they can be simulated by the host CPU.
Run
The command that releases the emulator or simulator from HALT, allowing it
to run the application code and change or respond to I/O in real-time.
SFR
Special Function Registers of a PICmicro MCU.
Simulator
A software program that models the operation of the PICmicro
microprocessor.
Simulator Stimulus
Data generated to exercise the response of MPSIM Simulator to external
signals. Often the data is put into the form of a list of actions in a text file.
Single Step
This command steps though code, one instruction at a time with MPSIM
Simulator or an emulator. After each instruction, MPLAB IDE updates register
windows, watch variables, and status displays, so you can analyze and debug
instruction execution.
You can also single step C compiler source code, but instead of executing
single instructions, MPLAB IDE will execute all assembly level instructions
generated by the line of the high level C statement.
DS41174A-page 70
2001 Microchip Technology Inc.
Glossary
Source
Source code, usually a text file of assembly instructions or C code.
Special Function Registers
Registers that control I/O processor functions, I/O status, timers, or other
modes or peripherals.
Stack
“Push-Down” list of calling routines. Each time a PICmicro microcontroller
executes a call or responds to an interrupt, the software pushes the return
address to the stack. A return command pops the address from the stack.
Step-Into
This command is the same as Single Step. Step-Into (as opposed to StepOver) follows a CALL instruction into a subroutine.
Step-Over
Step-Over allows you to debug code without stepping into subroutines. When
stepping over a CALL instruction, the next break point will be set at the
instruction after the CALL. If for some reason, the subroutine gets into an
endless loop or does not return properly, the next break point will never be
reached.
The Step-Over command is similar to Single Step, except for its handling of
CALL instructions.
Symbol
A label usually produced by an assembler or compiler that refers to machine
locations by function names, variable locations, constant declarations, source
line number, or other reference to user source code.
System Button
The System Button is located in the upper left corner of Windows and some
dialogs. This button usually has “Minimize,” “Maximize,” and “Close.” In some
MPLAB windows, additional modes or functions can be found under the
System Button.
Target
Refers to user hardware.
Target Application
Firmware residing on the target board.
Target Board
The circuitry and programmable device that makes up the target application.
Target Processor
The microcontroller device on the target application board that is being
emulated.
2001 Microchip Technology Inc.
DS41174A-page 71
PICDEM™ USB User’s Guide
Template
Lines of text that you build for inserting into your files at a later time. The
MPLAB Editor stores templates in template files.
Tool Bar
A row or column of icons that you can click on to execute MPLAB functions.
Trace
An emulator or simulator function that logs program execution. The emulator
logs program execution into its trace buffer, which is uploaded to MPLAB’s
trace window.
Trace Memory
Trace Memory contained within the Emulator. Trace Memory is sometimes
called the Trace Buffer.
Trigger Output
Trigger Output refers to an emulator output signal that can be generated at
any address or address range, and is independent of the trace and break
point settings. Any number of trigger output points can be set.
Upload
The Upload function transfers data from the emulator to the host PC, or from
the target board to the emulator.
USB
Universal Serial Bus. A popular bus for connecting peripherals to personal
computers.
Warning
An alert that is provided to warn you of a situation that would cause physical
damage to a device, software file, or equipment.
Watchdog Timer
A timer on a PICmicro microcontroller that resets the processor after a
selectable length of time.
Watch Variable
A variable that you may monitor during a debugging session. Watch windows
contain a list of watch variables that are updated at each break point.
DS41174A-page 72
2001 Microchip Technology Inc.
PICDEM™ USB USER’S GUIDE
Index
A
Applications .................................................... 10
Describing ................................................ 11
Integrating USB ........................................ 39
B
Breakpoints .................................................... 65
Buttons ........................................................... 36
C
Codes ............................................................. 61
Command ................................................ 62
Host to PS/2 ...................................... 62
PS/2 Mouse ....................................... 63
PS/2 to Host ...................................... 63
Scan ......................................................... 61
PS/2 Keycodes .................................. 61
Components ..................................................... 9
Configuration Bits ........................................... 65
Cursor Demonstration .................................... 48
MPLAB ICE .............................................. 49
PIC16C745/765 ....................................... 48
Customer Support ............................................ 7
D
Default Demonstration .................................... 10
Demonstration Code ...................................... 13
Descriptors
Creating ................................................... 11
Multiple ..................................................... 46
Report - Debugging .................................. 11
Development Systems
Compilers ................................................... 6
Emulators ................................................... 6
MPLAB IDE ................................................ 7
Programmers ............................................. 6
Development Systems Customer
Notification Service .............................. 5
Document Conventions .................................... 2
Updates ...................................................... 3
2001 Microchip Technology Inc.
E
EEPROM ........................................................ 66
Emulation ........................................................ 50
Emulator System ............................................ 66
Endpoints, Multiple ......................................... 23
Error Counter .................................................. 47
Extended Microcontroller Mode ...................... 66
External Input Line .......................................... 66
External RAM .................................................. 67
F
Function Call Reference
GetEPn ..................................................... 43
PutEPn ..................................................... 42
Functions
CheckSleep ........................................ 43, 45
ConfiguredUSB ........................................ 44
InitUSB ............................................... 42, 44
ServiceUSBlnt .......................................... 43
SetConfiguration ...................................... 44
SoftDetachUSB ........................................ 43
StallUSBEP/UnstallUSBEP ...................... 43
G
Gameport ........................................................ 13
Connector Pinout ..................................... 32
Hardware Implementation ........................ 14
Identification Codes .................................. 17
Reading Firmware .................................... 15
Translation ............................................... 16
USB Translator ......................................... 13
Gameport/PS/2 Combination .......................... 23
GetEPn ........................................................... 47
Glossary .......................................................... 65
H
HID Class ........................................................ 48
DS41174A-page 73
PICDEM™ USB User’s Guide
I
ICE .................................................................. 67
IDE .................................................................. 67
Internet Address ............................................... 4
Interrupt Structure ...........................................40
Buffer Allocation ....................................... 41
File Packaging .......................................... 41
Function Call Reference ........................... 42
Processor Resources ............................... 40
RAM ......................................................... 40
ROM ......................................................... 40
Stack Levels ............................................. 40
J
Jumpers .......................................................... 36
K
Keypad
Connector Pinout ...................................... 35
L
LCD
Connector Pinout ...................................... 35
Hardware Implementation ........................25
Macintosh Code Support .......................... 30
PC Code Support ..................................... 29
PC/Macintosh Identification ......................29
Report Descriptor ..................................... 27
USB Command Set .................................. 27
LCD Driver Firmware ...................................... 26
LCD Text Display ............................................ 25
M
Microchip Internet Web Site .............................. 4
Microcontroller Mode ...................................... 68
Microprocessor Mode ..................................... 68
MPLAB ............................................................ 68
MPLAB ICE ..................................................... 68
MPSIM ............................................................ 68
O
Off-Chip Memory .............................................69
Oscillator Support ............................................31
Canned .....................................................31
Crystal ......................................................32
Resonator .................................................31
P
Pass Counter ..................................................69
PICMASTER ...................................................69
Power ..............................................................37
Bus Power ................................................37
Self Power ................................................37
Project .............................................................69
PS/2 ................................................................17
Connector Pinout ......................................33
Firmware ...................................................20
Hardware Implementation ........................17
PutEPn ............................................................47
R
Recommended Reading ...................................3
RS-232
Connector Pinout ......................................34
S
Schematics ......................................................54
T
Text Terminal
USB Command Set
Input Commands ................................29
Trace ...............................................................72
Troubleshooting ..............................................51
U
USB
Connector Pinout ......................................36
Software Interface ....................................39
Status on PORTB .....................................47
W
Warranty Registration .......................................3
WWW Address ..................................................4
DS41174A-page 74
2001 Microchip Technology Inc.
Index
NOTES:
2001 Microchip Technology Inc.
DS41174A-page 75
WORLDWIDE SALES AND SERVICE
AMERICAS
ASIA/PACIFIC
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Taiwan
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EUROPE
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08/01/01
DS41174A-page 76
2001 Microchip Technology Inc.