AN_201 FT-X MTP memory Configuration

Future Technology Devices International
Application Note
AN_201
FT-X MTP memory Configuration
2.0
Issue Date: 2013-12-18
This application note describes the MTP Memory Map of the FTDI FT-X series of
chips. This MTP memory is used for storing configuration data in the FT-X series
of devices. The MTP Memory can be read and written over USB on all FT-X series
devices, and can also be read and written over I2C on the members of the FT-X
family which include I2C interfaces.
This application note only covers the MTP memory map. It does not
cover the methods of reading and writing the memory. These are
covered in the individual device datasheet and the D2XX Programmers
Guide.
Use of FTDI devices in life support and/or safety applications is entirely at the user’s risk, and the user agrees
to defend, indemnify and hold harmless FTDI from any and all damages, claims, suits or expense resulting
from such use.
Future Technology Devices International Limited (FTDI)
Unit 1, 2 Seaward Place, Glasgow G41 1HH, United Kingdom
Tel.: +44 (0) 141 429 2777 Fax: + 44 (0) 141 429 2758
Web Site: http://ftdichip.com
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Application Note
AN_201 FT-X MTP memory Configuration
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Table of Contents
1
Introduction .................................................................... 3
2
Overview of the MTP Memory .......................................... 4
3
2.1
Memory Areas ........................................................................... 4
2.2
Reading and Writing Commands ............................................... 4
2.3
Programming over I2C and USB ................................................ 4
2.4
Important Warnings and Notes ................................................. 5
Memory Map.................................................................... 6
3.1
Memory Map Diagram ............................................................... 6
4
User Data Area ................................................................ 8
5
String descriptor Data ..................................................... 9
6
FTDI Configuration Data ............................................... 10
7
Configuration Descriptor data ....................................... 11
7.1
Misc Config ............................................................................. 11
7.2
USB VID .................................................................................. 12
7.3
USB PID .................................................................................. 12
7.4
BCD Release Number .............................................................. 12
7.5
Max Power & Config Description Value ................................... 12
7.6
Device & Peripheral Control .................................................... 13
7.7
DBUS & CBUS Control.............................................................. 14
7.8
Manufacturer String Descriptor ............................................... 14
7.9
Product String Descriptor ....................................................... 14
7.10 Serial Number String Descriptor ............................................. 14
7.11 I2C Address + Options ............................................................ 15
7.12 CBUS[6:0] Mux Control .......................................................... 15
8
Calculating the Checksum ............................................. 18
8.1
9
Checksum Calculation Example ............................................... 19
Contact Information ...................................................... 21
Appendix A – References ................................................... 22
Document References ..................................................................... 22
Acronyms and Abbreviations ........................................................... 22
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Application Note
AN_201 FT-X MTP memory Configuration
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Appendix B – List of Tables & Figures ................................ 23
Appendix C – Revision History ........................................... 24
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AN_201 FT-X MTP memory Configuration
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1 Introduction
This application note describes the internal MTP (Multi-Time Programmable) memory map configuration
area of the FT-X devices, also known as the X-Chip Series. This memory is used to hold information such
as the Vendor ID, Product ID, String Descriptors, I2C address and functions assigned to each available
Control Bus (CBUS) pin.
The MTP memory is available in all FT-X series devices and performs the same function as the internal
EEPROM in the FT232R/FT245R devices.
This document details the data stored in each word of the MTP memory map so that a user application
can determine which values to write to configure the chip.
This application note does not cover the User area of MTP memory or the details of writing the values to
the MTP (over I2C or USB). These are covered in the datasheet for each FT-X device and also in the
D2XX Programmers Guide.
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2 Overview of the MTP Memory
2.1 Memory Areas
There are two main areas of MTP memory, which are the User area and the Configuration area. A more
detailed memory map is provided in the following section.
User Area
This area can be used for storing application-specific data, for example a calibration constant in an analog
measurement system. It is not used for chip configuration. This can be useful as it can avoid the cost and
space needed to fit a separate EEPROM chip on the application board when only a few values need to be
stored.
User area programming is not covered in the remainder of this document as it is covered in the FT-X
device datasheet (for programming over I2C in devices which include an I2C interface) and in the D2XX
Programmers Guide for all FT-X devices. Note that the user area is not included in the MTP checksum and
so modification of the user area does not require re-calculation of the checksum.
Note: An application intending to write to the user area of the MTP memory should take care not to
unintentionally change any data in the configuration area.
Configuration Area
The device is initially supplied with the configuration areas of the MTP memory already programmed with
default values and so in many cases the device can be used without any MTP programming at all.
Changing the contents of the Configuration areas of the MTP memory programming is only required when
the final application requires the settings to be customised.
Some examples of customising the configuration settings include:



When the FT-X is to be given a custom Vendor (VID) and/or Product ID (PID)
When the FT-X is to be given a specific serial number
When the application requires different settings on the CBUS pins e.g. to configure the pins to
output the functional signals necessary for battery charging as shown in Application Note,
AN_175 (see References Section).
2.2 Reading and Writing Commands
This application note covers the memory map itself but does not cover the methods of reading and
writing the memory, because this depends on the interface used. Further details on the read and write
commands themselves can be found in the following documents:


For applications which will read and write the MTP memory over I2C, the device datasheet
contains the commands required to read and write the MTP memory. This includes the FT200XD
and FT201X.
For applications which will program the MTP memory over USB, the D2xx Programmers Guide
contains the commands required to read and write MTP memory. This includes all members of the
FT-X device family.
2.3 Programming over I2C and USB
FTDI provide two methods of programming the MTP memory. These are designed to make it as easy and
as efficient as possible to do this whether executed as part of the production/test process or the final
application.
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Programming the MTP memory over USB
The MTP memory on all FT-X devices can be programmed over USB. This method is similar to the other
FTDI devices such as the FT232R. No additional hardware, connections or programming voltages are
required. The device is simply connected to the host computer in the same way that it would be for
normal applications, and the programming is carried out over USB.
There are two methods for programming over USB:

FTDI provide a utility called FT_Prog which can be used to program the MTP memory. This utility
provides a graphical user interface and can be used to configure the device without needing to
know the actual memory map. The FT-Prog utility is provided free-of-charge from the FTDI
website, and can be found at the link below. Please use the latest version available. The user
guide is also available at this link. Note that the FT-X devices require FT_Prog version 2.6.8 or
later.
http://www.ftdichip.com/Support/Utilities.htm#FT_Prog

D2XX commands can also be used to program the MTP memory from within user applications. For
more information on the commands available, please see the D2XX Programmers Guide (See
Reference [2] in Appendix A – References). The remainder of this document can be used to
determine the values in each location in order to configure the device as required.
Note that when programming over USB, word addresses are used.
Programming the MTP memory over I2C
In FT-X devices with I2C interfaces, it is also possible to program the MTP memory over I2C by using
special commands.
This can be beneficial when no USB host is available to configure the MTP memory. For example, a bedof-nails test jig where no host is present as part of a production and test set-up. Also, if the FT-X is
acting as a bridge between a microcontroller/FPGA and a USB host as part of an application, the
microcontroller/FPGA can modify or program the MTP memory data. This could include changes to the
configuration data (such as serial number) and/or storing application data in the user area of the MTP
memory.
Note that when programming over I2C, byte addresses are used.
2.4 Important Warnings and Notes
Care must be taken when performing write operations on the MTP memory

Failure to recalculate a checksum after changing any of the configuration areas may prevent
correct operation. An incorrect checksum will cause the device to use default values.

Modifying the MTP data may cause errors and can completely change the operation of the chip.
Ensure that the effect of the modification has been considered before writing the new value to
MTP memory. For example, switching to the external oscillator mode will prevent the device from
running from its internal oscillator. This cannot be changed back unless an external crystal is
temporarily connected to allow the MTP memory to be programmed to select the internal clock
source again.

It should be verified that the application code causes only the intended area to be modified and
that the value written is valid for that MTP memory location. For example, an application
intending to write to the user area of the MTP memory should include safeguards to ensure that it
does not unintentionally write to an address in the configuration area. Values written should also
be valid values according to the tables in the following section.

Ensure that the application takes account of the MTP memory write cycle specification in the
datasheet of the FT-X device.
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3 Memory Map
The FT-X MTP memory has various areas which come under five main categories:





User Areas
Checksum Area
String Descriptor Area
FTDI Configuration Area
Chip Configuration Area
3.1 Memory Map Diagram
Figure 3.1 illustrates a simplified memory map of the MTP memory, showing the address ranges of the
areas listed above.
Memory Area Description
Word Address
Byte Address
User Area 2
Accessible via USB and I2C
0x3FF - 0x80
0x7FF – 0x100
Checksum
0x7F
0xFF – 0xFE
String Descriptor Area
Accessible via USB and I2C
0x7D - 0x50
0xFB – 0xA0
FTDI Configuration Area
Cannot be written
0x4F - 0x40
0x9F – 0x80
User Area 1
Accessible via USB and I2C
0x3F - 0x12
0x7F – 0x24
Chip Configuration Area
Accessible via USB and I2C
0x11 - 0x00
0x23 - 0x00
Figure 3.1:
Simplified memory map for the FT-X
A more detailed memory map can be found in Figure 3.2 below.
In Figure 3.2, bytes highlighted in pink represent areas of memory which are protected while the bytes
highlight in blue represent areas of memory which can be programmed with user defined data.
Note that Figure 3.1 shows the entire address range for that block. For example, FTDI Configuration Area
includes bytes 0x9F to 0x80. However, Figure 3.2 shows the address of the right-hand byte or word only
instead of the address range. (e.g. FTDI Configuration Area shows 0x9C to 0x80).
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Additional User Memory Space
Clearance No.: 298
0x3FE
↓
0x80
0x7FC
↓
0x100
0x7E
0xFC
0x7C
↓
0x50
0xF8
↓
0xA0
- Address 0x80 -0x3FF is used specifically for customers data
- can be written to using USB & I2C interfaces
- this user area is excluded from the checksum calculation
Checksum
UNUSED
String Descriptor Space
Used to hold the following:
Serial Number String Descriptor
Product String Descriptor
Manufacturer String Descriptor
CH
SU
K
EC
ED
M
M
Factory Configuration Data
Configuration data is used regardless of checksum
Not writable by the user
User Memory Space
0x4E
0x9C
0x4C
0x98
0x4A
0x94
0x48
0x90
0x46
0x8C
0x44
0x88
0x42
0x84
0x40
0x80
0x3E
↓
0x12
0x7C
↓
0x24
- Address 0x12 -0x3F is used specifically for customers data
- can be written to using USB & I2C interfaces
- this user area is excluded from the checksum calculation
unused
CBUS 5
CBUS 4
CBUS 1
CBUS 0
I2C Slave Device ID 2
I2C Slave Device ID 1
Serial Str Description Length
Serial Str Description Pointer
Man. Str. Description Length
Man. Str. Description Pointer
C
CHE
CBUS 6
0x10
0x20
CBUS 2
0x0E
0x1C
I2C Slave Device ID 3
0x0C
0x18
0x0A
0x14
CBUS 3
U
KS
Device & Peripheral Control
ED
MM
I2C Slave Address
Prod. Str Description Length
0x08
0x10
CBUS IO Ctrl
0x06
0x0C
IOBUS Ctrl
0x04
0x08
USB BCD Release Number
USB PID
0x02
0x04
USB VID
Misc Config
0x00
0x00
words
bytes
byte 3
byte 2
MAX Power
Prod. Str Description Pointer
byte 1
Config Description Value
Byte 0
FT-X MTP MEMORY MAP
Figure 3.2:
Memory map for the FT-X
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4 User Data Area
All locations within this range are freely programmable; no areas have special functions. There is no
checksum for the user area.
Note that the application should take into account the specification for the number of write cycles in the
device datasheet if it will be writing to the MTP memory multiple times.
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5 String descriptor Data
This area stores the following strings:
-
Serial Number String Descriptor
-
Product String Descriptor
-
Manufacturer String Descriptor
The checksum must be re-calculated and re-programmed after writing this area. The locations pointing to
the different descriptors and their length must also be programmed. See sections: 7.8, 7.9 and 7.10.
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6 FTDI Configuration Data
This area is written during production test by FTDI and can never be modified by the user. There are no
parameters here that any application should ever need to modify. Attempts to write to this area will fail.
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7 Configuration Descriptor data
This area stores the configuration data for the device, including the data which is returned to the host in
the configuration descriptors, the hardware configuration (signal assigned to each CBUS pin for example)
and the IDs and Address for the I2C interface (in the case of the FT200XD and FT201X).
This area is included in the checksum, and the checksum must therefore be re-calculated whenever the
contents of this area are modified.
7.1 Misc Config
Bit
0
Mode Function
BCD Enable
Description
Enable Battery charge detection. This must be
enabled to allow the device to detect a Dedicated
Charging Port.
1 = Enable (Battery Charge Detection is on)
0 = Disable (Battery Charge Detection is off)
1
Force Power Enable
When BCD is enabled and a BCD port is detected,
force power enable asserts the power enable signal
on CBUS
1 = Enable (Force Power Enable is on)
0 = Disable (Force Power Enable is off)
2
De-activate Sleep
When BCD is enabled and a BCD port is detected, deactivate sleep forces the device never to go into
sleep mode
1 = Enable (De-Activate Sleep function is on)
0 = Disable (De-Activate Sleep function is off)
RS485 Echo suppression Enable
3
RS485 Echo Suppression
1 = Enable (Echo are suppressed)
0 = Disable (Echo not suppressed)
4
Ext. OSC
5
Ext. OSC Feedback Resistor Enable
0 = Use INTERNAL oscillator
1 = Use EXTERNAL oscillator
0 = Ext. OSC Feedback resistor enabled
1 = Ext. OSC Feedback resistor disabled
Indicates that a CBUS pin has been allocated to
VBUS sense mode. When self powered, use this
mode to determine when the device is connected to a
powered host.
6
CBUS pin set for VBUS sense
Used when operating in a self powered mode and is
used to prevent forcing current down the USB lines
when the host or hub is powered off.
1 = A CBUS pin has been allocated to VBUS sense
mode.
0 = A CBUS pin has not been allocated to VBUS
sense mode.
7
Load D2XX or VCP Driver
Enables software to select which driver to load
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1 = Load VCP (load VCP layer on top of D2xx)
0 = Load D2xx (i.e. do not load VCP layer)
15:8
unused
Table 7.1: Misc Config Bit Description
7.2 USB VID
Bit
Mode
Description
15:0
USB Vendor Identifier
A 16-bit number used for vendor identification, the
default for the FTX devices is 0x0403
Table 7.2: USB VID
7.3 USB PID
Bit
Mode
Description
15:0
USB Product Identifier
A 16-bit number used for product identification, the
FT-X has been assigned a PID of 0x6015 by default.
Table 7.3: USB PID
7.4 BCD Release Number
Bit
15:0
Mode
Description
Binary Coded Decimal Release Number
This is used in the USB device descriptor which
contains information about the major and minor
releases of the device. It is coded as binary coded
decimal. Refer to chapter 9 in the USB specification
for more detail.
For example, 0x0200 is USB 2.0
Table 7.4 BCD Release Number
7.5 Max Power & Config Description Value
Bit
Mode
4:0
Unused
Description
Reserve to 0
Setting this configures the FT232EX to allow itself to
be remotely woken by something other than USB.
5
Enable USB Remote wakeup
0 = Disabled remote wakeup
1 = Enable remote wakeup
6
Self Powered
7
Unused
0 = Indicates that the FT-X is powered by USB bus
1 = Indicates that the FT-X is self powered
Reserve to 1
Used to set the maximum current limit the
device/product can support from USB (in units of
2mA). For example, 0x2D is 45 and gives 90mA.
Table 7.5: Max power and USB Configuration Options
15:8
Max Power Value
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7.6 Device & Peripheral Control
Bit
Mode
1:0
Unused
Description
When the FT-X enters USB suspend, all IO, by
default, are pulled up. Set this bit to 1 to pull down
all IO when suspended
2
USB suspend pull down enable
0 = Only IO inputs are pulled up when USB suspend.
This is the normal operating mode (*)
1 = All IO are made inputs and are pulled down
when USB suspend (**)
3
Enable/Disable USB Serial Number
When USB requests a device descriptor, if this bit is
set to 1 then it indicates to the USB host that a
serial number is available
FT1248 Clock polarity
4
FT1248 CPOL
0 = Clock is active low
1= Clock is active high
FT1248 Bit Order
5
FT1248 BORD
0= Data transmitted MSB to LSB
1 = Data transmitted LSB to MSB
FT1248 flow control enable
6
FT1248 Flow Control Enable
When enabled turns on FT1248 flow control when
SS_n is inactive.
Disable the I2C Schmitt pad control
7
Disable I2C Schmitt
8
Invert TXD
Set to 1, to invert the TXD signal
9
Invert RXD
Set to 1, to invert the RXD signal
10
Invert RTS
Set to 1, to invert the RTS signal
11
Invert CTS
Set to 1, to invert the CTS signal
12
Invert DTR
Set to 1, to invert the DTR signal
13
Invert DSR
Set to 1, to invert the DSR signal
14
Invert DCD
Set to 1, to invert the DCD signal
15
Both I2C pads have Schmitt triggers. These can be
disabled by setting 1 to this bit.
Invert RI
Set to 1, to invert the RI signal
Table 7.6: Device & Peripheral Control
* Mode 0 has three exceptions to the all inputs are pulled up rule:
1. The I2C SDA and SCL pins are never pulled up. Pull-ups for I2C mode are the responsibility of the I2C
master.
2. When a CBUS pin is in VBUS Sense mode the CBUS input will not be pulled up.
3. When in synchronous or asynchronous bit bang mode, pull up control is under user control.
** Mode 1 (All IO’s pulled down) is designed for the case where the FTX PWREN# pin is used to switch a
FET, which will provide to the rest of the circuit/board. PWREN# is activated when a part is fully
operational (not suspended or in reset) and the USB state is configured. All I/O’s will remain pulled down
until this condition occurs.
*** Disable_I2C_Schmitt can be over-ridden by the DBUS_Schmitt_Trigger_Enable setting (Section 7.7)
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7.7 DBUS & CBUS Control
Bit
Mode
Description
1:0
DBUS Drive Current Strength
Sets the drive current for all DBUS pads
00 = 4mA, 01 = 8mA, 10 = 12mA, 11 = 16mA
Sets the slew rate for all DBUS pads
2
DBUS Slew Rate
0 = Fast slew rate
1 = Slow slew rate
3
DBUS Schmitt Trigger Enable
5:4
CBUS Drive Current Strength
6
CBUS Slew Rate
7
CBUS Schmitt Trigger Enable
Sets the IO pad to operate with a Schmitt Trigger. 0
= normal mode, 1 = Schmitt
Sets the drive current for all CBUS pads
00 = 4mA, 01 = 8mA, 10 = 12mA, 11 = 16mA
Sets the slew rate for all CBUS pads
0 = Fast slew rate, 1 = Slow slew rate
Sets the pad to operate with a Schmitt Trigger. 0 =
normal mode, 1 = Schmitt
Table 7.7: IO Control
7.8 Manufacturer String Descriptor
Bit
Mode
7:0
Man. String Description Pointer
15:8
Description
Address pointer to the location in the MTP memory
of the string describing the manufacturer
Man. String Description Length
Length of the string
Table 7.8: Manufacturer String Descriptor
Note that the string descriptor pointers are byte addressable.
7.9 Product String Descriptor
Bit
Mode
7:0
Prod. String Description Pointer
15:8
Description
Address pointer to the location in the MTP memory
of the string describing the product
Prod. String Description Length
Length of the string
Table 7.9: Product String Descriptor
Note that the string descriptor pointers are byte addressable.
7.10 Serial Number String Descriptor
Bit
Mode
7:0
Serial No. String Description Pointer
15:8
Description
Address pointer to the location in the MTP memory
of the string describing the serial number
Serial No. String Description Length
Length of the string
Table 7.10: Serial Number String Descriptor
Note that the string descriptor pointers are byte addressable.
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7.11 I2C Address + Options
Bit
Mode
Description
14:0
I2C Slave Address
15
Unused
Programmable I2C Slave Address
Table 7.11: I2C Slave Address
Bit
Mode
Description
7:0
I2C Device ID Byte 1
I2C Device ID
15:8
Bit
I2C Device ID Byte 2
I2C Device ID
Table 7.12: I2C Device ID
Mode
7:0
I2C Device ID Byte 3
Table 7.13: I2C Device ID
Description
I2C Device ID
7.12 CBUS[6:0] Mux Control
Each individual CBUS pin (up to 7 are available depending on the package) is controlled by a separate
value, which represents the signal assigned to that pin as shown in the following tables. The mode
corresponding to each value is also shown in Table 7.18.
Bit
Mode
7:0
CBUS0 Mux Control
15:8
Mode
7:0
CBUS2 Mux Control
Description
Maps various CBUS features to CBUS2 IO pad
CBUS3 Mux Control
Maps various CBUS features to CBUS3 IO pad
Table 7.15: CBUS[3:2] Control
Bit
Mode
7:0
CBUS4 Mux Control
15:8
Maps various CBUS features to CBUS0 IO pad
CBUS1 Mux Control
Maps various CBUS features to CBUS1 IO pad
Table 7.14: CBUS[1:0] Control
Bit
15:8
Description
Description
Maps various CBUS features to CBUS4 IO pad
CBUS5 Mux Control
Maps various CBUS features to CBUS5 IO pad
Table 7.16: CBUS[5:4] Control
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Bit
Mode
7:0
CBUS6 Mux Control
15:8
Unused
Clearance No.: 298
Description
Maps various CBUS features to CBUS6 IO pad
Table 7.17: CBUS[6] Mux Control
The mode associated with each value is shown below.
MUX
Sel
Mode
0
Tristate
1
RXLED#
Description
IO Pad is tri-stated
Value = 00000000
Indicates that there is RX activity, can be used as
status for LED
Value = 00000001
2
TXLED#
Indicates that there is TX activity, can be used as
status for LED
Value = 00000010
3
TX&RXLED#
Indicates that there is TX + RX activity, can be used
as status for LED
Value = 00000011
4
PWREN#
Indicates that the USB has been configured when
asserted low, and when suspended is de-asserted
high
Value = 00000100
5
SLEEP#
Asserted low when in USB suspend, typically used to
power down external logic devices.
Value = 00000101
6
Drive_0
7
Drive_1
8
GPIO
9
TXDEN
10
CLK24MHz
11
CLK12MHz
12
CLK6MHz
13
BCD_Charger
Drive a constant 0
Value = 00000110
Drive a constant 1
Value = 00000111
Standard IO port for CBUS bit bang mode
Value = 00001000
Enable transmit for RS485 mode
Value = 00001001
Output 24 MHz clock
Value = 00001010
Output 12 MHz clock
Value = 00001011
Output6 MHz clock
Value = 00001100
Battery Charger Detect, indicates when the device is
connected to a dedicated battery charger host,
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AN_201 FT-X MTP memory Configuration
2.0
Document Reference No.: FT_000572
Clearance No.: 298
active high.
Value = 00001101
14
15
BCD_Charger#
I2C_TXE#
Inverse of BCD
Value = 00001110
Transmit buffer empty, used to indicate to I2C
master device status of the FT232EX transmit buffer
Value = 00001111
16
I2C_RXF#
Receive buffer full, used to indicate to I2C master
device status of FT232EX receive buffer
Value = 00010000
17
VBUS_Sense
Detect when VBUS is present via the appropriate AC
IO pad
Value = 00010001
18
BitBang_WR#
19
BitBang_RD#
20
Time_Stamp
Synchronous Bit Bang Write strobe
Value = 00010010
Synchronous Bit Bang Read strobe
Value = 00010011
Toggle signal which changes state each time a USB
SOF is received
Value = 00010100
21
Keep_Awake#
Stop the part entering suspend when unplugged or
suspended. This mode allows the MTP memory to be
accessed over a peripheral, even although
disconnected from the USB or suspended.
Value = 00010101
Table 7.18: CBUS Multiplexer Select
17
Copyright © 2014 Future Technology Devices International Limited
Application Note
AN_201 FT-X MTP memory Configuration
2.0
Document Reference No.: FT_000572
Clearance No.: 298
8 Calculating the Checksum
This is a unique word stored in the MTP memory which is used to verify the contents of the non-user
areas are correct. This single word checksum covers all of the check-summed areas of MTP.
At power on, the FT-X reads and decodes the checksum from the MTP memory, allowing it to confirm
that the contents of the MTP memory are valid and can be used. If the checksum is invalid then the FT-X
shall use default values which have been hard-coded in its logic instead.
An example of generating the checksum is shown below:
Variables Used:
1
Checksum, TempChecksum, DataWord, AddressCounter
Initialise variables:
Checksum = 0xAAAA, AddressCounter = 0x00
Write data and calculate checksum for words 0x00 to 0x11 (byte addresses 0x00 – 0x23)
2
Get next Dataword
3
Write Dataword to MTP at address = AddressCounter
4
Exclusive OR the current DataWord with the checksum
TempChecksum = DataWord XOR Checksum
5
Rotate TempChecksum 1 bit to the Left (bit 0 -> bit 1, bit 1 -> bit 2 … bit 15 -> bit 0)
TempChecksum = TempChecksum rotated to left
6
Checksum = TempChecksum
7
Increment AddressCounter to point to next word
8
Is address 0x12?
No -> Go To Step 2
Yes -> Go to Step 9
Write data and update the checksum for words 0x40 to 0x7E (byte addresses 0x80 – 0xFD)
9
AddressCounter = 0x40
10
Get next Dataword
11
Write Dataword to MTP at address = AddressCounter
12
Exclusive OR the current DataWord with the checksum
TempChecksum = DataWord XOR Checksum
13
Rotate TempChecksum 1 bit to the Left (bit 0 -> bit 1, bit 1 -> bit 2 … bit 15 -> bit 0)
TempChecksum = TempChecksum rotated to left
14
Checksum = TempChecksum
15
Increment AddressCounter to point to next word
16
Is address 0x7F?
No -> Go To Step 9
Yes -> Go to Step 17
Write the checksum
17
Write checksum to address 0x7F
18
Copyright © 2014 Future Technology Devices International Limited
Application Note
AN_201 FT-X MTP memory Configuration
2.0
Document Reference No.: FT_000572
Clearance No.: 298
8.1 Checksum Calculation Example
An example is shown below which will read the contents of an FT-X series device and calculate the
checksum using the algorithm shown above.
// NOTE:
//
//
#include
#include
#include
#include
This code is provided as an example only and is not supported or guaranteed by FTDI.
It is the responsibility of the recipient/user to ensure the correct operation of
any software which is created based upon this example.
<windows.h>
<stdio.h>
"ftd2xx.h"
"stdafx.h"
int main(int argc, char* argv[])
{
unsigned short Checksum = 0xAAAA;
unsigned char AddressCounter = 0x00;
unsigned short TempChecksum = 0x0000;
unsigned short Data = 0x0000;
unsigned short CheckSumLocation = 0x7F;
//
//
//
//
//
Variable for checksum value
Variable for address counter
Used whilst calculating checksum
Used to hold current data value
Address at which checksum stored in FT-X
FT_HANDLE fthandle;
FT_STATUS status;
printf("###########################################################\n");
printf("This program calculates the checksum of an FT-X series chip\n");
printf("###########################################################\n\n\n");
// Open the first device connected to the PC
status = FT_Open(0, &fthandle);
if(status != FT_OK)
printf("open status not ok %d\n", status);
else
printf("open status ok %d\n", status);
// Starting at Word address 0x00
AddressCounter = 0x00;
// Calculation uses addresses from 0x00 up to 0x7E (checksum itself is located at 0x7F)
while(AddressCounter < CheckSumLocation)
{
// Read the word from MTP and print it on the screen
status = FT_ReadEE(fthandle, AddressCounter, &Data);
printf("Memory location %x is... %x \n", AddressCounter, Data);
// EXOR the data with the current checksum and then rotate one bit to the left
TempChecksum = (unsigned short)(Data ^ Checksum);
Checksum = (unsigned short)((TempChecksum << 1) | (TempChecksum >> 15));
// Go to next word address.
// If we have reached word address 0x12, then skip forward to address 0x40
AddressCounter ++;
if(AddressCounter == 0x12)
AddressCounter = 0x40;
}
// Checksum is now ready
printf("\n\nChecksum is %x\n",Checksum);
printf("\n\nPress a key to continue\n");
// Wait for a key to be pressed
getchar();
// Close the device
status = FT_Close(&fthandle);
}
Note that the above example does not program the MTP or re-program the existing checksum in the
device – it will only read the MTP contents and display the checksum calculated from them.
19
Copyright © 2014 Future Technology Devices International Limited
Application Note
AN_201 FT-X MTP memory Configuration
2.0
Document Reference No.: FT_000572
Clearance No.: 298
The screen-shots below illustrate the output of the program.
Figure 8.1:
Screen shot taken from the sample code
When developing applications which re-calculate the checksum, the value obtained can be checked
against that shown in FT_Prog for the same device. Note that the actual data is stored in byte-reversed
format and hence the checksum shows as FF6F in FT_Prog’s memory window.
FT_Prog can be downloaded free from the FTDI website (see Appendix A – References)
Word
0000:
0008:
0010:
0018:
0020:
0028:
0030:
0038:
0040:
0048:
0050:
0058:
0060:
0068:
0070:
0078:
0000
AA1E
0000
0000
0000
0000
0000
0000
1936
0000
0A03
4600
4600
3200
0000
0000
0304
C812
0000
0000
0000
0000
0000
0000
E6C9
0000
4600
5400
5400
3300
0000
0000
1560
2200
0000
0000
0000
0000
0000
0000
0100
4442
5400
3200
4400
3500
0000
0000
0010
0000
0000
0000
0000
0000
0000
0000
D3E6
5655
4400
3300
4900
5200
0000
0000
802D
0000
0000
0000
0000
0000
0000
0000
99B0
3559
4900
3100
1203
5300
0000
0000
0800
0808
0000
0000
0000
0000
0000
0000
4000
544D
1E03
5800
4600
0000
0000
0000
0000
0808
0000
0000
0000
0000
0000
0000
0000
0000
5500
4500
5400
0000
0000
0000
A00A
0000
0000
0000
0000
0000
0000
0000
0000
0000
4D00
2000
5800
0000
0000
FF6F
Note: Ensure that the device is not
open in any other applications (such as
the example code above) before
scanning with FT_Prog as the device
can only be opened by one application
at a time.
Figure 8.2:
FT Prog screenshot and full memory window contents
20
Copyright © 2014 Future Technology Devices International Limited
Application Note
AN_201 FT-X MTP memory Configuration
2.0
Document Reference No.: FT_000572
Clearance No.: 298
9 Contact Information
Head Office – Glasgow, UK
Branch Office – Tigard, Oregon, USA
Future Technology Devices International Limited
Unit 1, 2 Seaward Place, Centurion Business Park
Glasgow G41 1HH
United Kingdom
Tel: +44 (0) 141 429 2777
Fax: +44 (0) 141 429 2758
Future Technology Devices International Limited
(USA)
7130 SW Fir Loop
Tigard, OR 97223-8160
USA
Tel: +1 (503) 547 0988
Fax: +1 (503) 547 0987
E-mail (Sales)
E-mail (Support)
E-mail (General Enquiries)
E-Mail (Sales)
E-Mail (Support)
E-Mail (General Enquiries)
[email protected]
[email protected]
[email protected]
Branch Office – Taipei, Taiwan
Future Technology Devices International Limited
(Taiwan)
2F, No. 516, Sec. 1, NeiHu Road
Taipei 114
Taiwan , R.O.C.
Tel: +886 (0) 2 8791 3570
Fax: +886 (0) 2 8791 3576
E-mail (Sales)
E-mail (Support)
E-mail (General Enquiries)
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
Branch Office – Shanghai, China
Future Technology Devices International Limited
(China)
Room 1103, No. 666 West Huaihai Road,
Shanghai, 200052
China
Tel: +86 21 62351596
Fax: +86 21 62351595
E-mail (Sales)
E-mail (Support)
E-mail (General Enquiries)
[email protected]
[email protected]
[email protected]
Web Site
http://ftdichip.com
System and equipment manufacturers and designers are responsible to ensure that their systems, and any Future Technology Devices
International Ltd (FTDI) devices incorporated in their systems, meet all applicable safety, regulatory and system-level performance
requirements. All application-related information in this document (including application descriptions, suggested FTDI devices and other
materials) is provided for reference only. While FTDI has taken care to assure it is accurate, this information is subject to customer
confirmation, and FTDI disclaims all liability for system designs and for any applications assistance provided by FTDI. Use of FTDI
devices in life support and/or safety applications is entirely at the user’s risk, and the user agrees to defend, indemnify and hold
harmless FTDI from any and all damages, claims, suits or expense resulting from such use. This document is subject to change without
notice. No freedom to use patents or other intellectual property rights is implied by the publication of this document. Neither the whole
nor any part of the information contained in, or the product described in this document, may be adapted or reproduced in any material
or electronic form without the prior written consent of the copyright holder. Future Technology Devices International Ltd, Unit 1, 2
Seaward Place, Centurion Business Park, Glasgow G41 1HH, United Kingdom. Scotland Registered Company Number: SC136640
21
Copyright © 2014 Future Technology Devices International Limited
Application Note
AN_201 FT-X MTP memory Configuration
2.0
Document Reference No.: FT_000572
Clearance No.: 298
Appendix A – References
Document References
[1]
FT_Prog utility for programming the MTP over USB
http://www.ftdichip.com/Support/Utilities.htm#FT_Prog
[2]
D2xx Programmers Guide
http://www.ftdichip.com/Support/Documents/ProgramGuides/D2XX_Programmer's_Guide(FT_00
0071).pdf
[3]
FT-X family product page
http://www.ftdichip.com/FT-X.htm
Acronyms and Abbreviations
Terms
CBUS
FT1248
Description
Configurable I/O pins on FTDI devices
FTDI Dynamic Parallel/Serial bus (between 1 and 8 bits wide)
I2C
Inter-Integrated Circuit bus
MTP
Multi-Time Programmable memory
PID
Product ID (for example, the FT-X devices use 0x6015 by default)
USB
Universal Serial Bus
VID
Vendor ID (for example, FTDI’s Vendor ID is 0x0403)
22
Copyright © 2014 Future Technology Devices International Limited
Application Note
AN_201 FT-X MTP memory Configuration
2.0
Document Reference No.: FT_000572
Clearance No.: 298
Appendix B – List of Tables & Figures
List of Tables
Table 7.1: Misc Config Bit Description ...................................................................... 12
Table 7.2: USB VID ................................................................................................... 12
Table 7.3: USB PID ................................................................................................... 12
Table 7.4 BCD Release Number ................................................................................ 12
Table 7.5: Max power and USB Configuration Options .............................................. 12
Table 7.6: Device & Peripheral Control ..................................................................... 13
Table 7.7: IO Control ................................................................................................ 14
Table 7.8: Manufacturer String Descriptor ................................................................ 14
Table 7.9: Product String Descriptor ........................................................................ 14
Table 7.10: Serial Number String Descriptor ............................................................ 14
Table 7.11: I2C Slave Address .................................................................................. 15
Table 7.12: I2C Device ID ......................................................................................... 15
Table 7.13: I2C Device ID ......................................................................................... 15
Table 7.14: CBUS[1:0] Control ................................................................................. 15
Table 7.15: CBUS[3:2] Control ................................................................................. 15
Table 7.16: CBUS[5:4] Control ................................................................................. 15
Table 7.17: CBUS[6] Mux Control ............................................................................. 16
Table 7.18: CBUS Multiplexer Select ......................................................................... 17
List of Figures
Figure 3.1:
Simplified memory map for the FT-X ..................................................... 6
Figure 3.2:
Memory map for the FT-X ...................................................................... 7
Figure 8.1:
Screen shot taken from the sample code ............................................. 20
Figure 8.2:
FT Prog screenshot and full memory window contents ........................ 20
23
Copyright © 2014 Future Technology Devices International Limited
Application Note
AN_201 FT-X MTP memory Configuration
2.0
Document Reference No.: FT_000572
Clearance No.: 298
Appendix C – Revision History
Document Title:
Document Reference No.:
Clearance No.:
Product Page:
Document Feedback:
Revision
AN_201 FT-X MTP memory Configuration
FT_000572
298
http://www.ftdichip.com/FT-X.htm
Send Feedback
Changes
Date
1.0
Initial Release
21/06/12
2.0
Updated Figure 3.2 to outline the correct area of memory which
is checksummed.
18/12/13
Corrected address range used in Section 8 checksum calculation.
Removed references to FT1248 as programming MTP over
FT1248 not currently supported.
Added example code in Section 8.1 to show calculation of a
checksum
24
Copyright © 2014 Future Technology Devices International Limited
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