x86 EAPI Windows

Please note that the EAPI Windows package is only available on request: Request EAPI
EAPI is intended to be installed on Windows 7 64-bit and Windows 10 64-bit.
On Windows 7 KB3033929 update must be installed on the system to support SHA-2 Code Signing Certificate.
More information about it is available at:
  1. Decompress the EAPI archive onto an USB drive.
  2. Plugin the USB drive to the Starterkit
  3. Run the Windows command prompt as administrator and navigate into the TqWin64EAPI_R01.0x folder on the USB drive
  4. Execute install.bat from the command prompt
The installation may fail if windows is configured to prohibit the installation of unsigned drivers. Please see Disable Windows driver signature verification for more information.
  1. Open Windows Device Manager
  2. Find System Devices→Tq driver.
  3. Select Uninstall and check “Delete the driver software for this device”

  1. Right click on TqDrv.sys file from this package and choose Properties→Details to locate file version.
  2. Make sure that TqDrv.sys file version and driver version in Device Manager are identical.
  3. Make sure that TqDrv.sys file from C:\Windows\System32\drivers is identical to one from this package.

For detailed functions description please refer to PICMG EAPI specification: COM_EAPI_R1_0.pdf
All examples are using the sample application TqApp.exe.
The TqApp is available in sources and is provided as a part of the EAPI package.

The EApiLibInitialize function has to be called at the beginning of every application.
An error will be returned if TQ driver is not installed on the system.

The EApiLibUnInitialize function has to be called at the end of every application.


Supported EAPI ID values:




Supported EAPI ID values:


Supported Values for EApiBoardGetValue function


  • Temperature sensors values are in 0.1 Kelvin.
  • Voltage sensors values are in millivolts.
  • Fan speed values are in RPM.
Some EApiBoardGetValue functions are not yet supported on certain modules.

Table of supported functions

Backlight Functions are only available if a suitable display is connected.
Latest Intel(R) HD Graphics driver has be installed on the system.
Backlight can only be enabled/disabled via BIOS.

Supported Functions

EApiVgaGetBacklightEnable Returns current Backlight Enable state
EApiVgaGetBacklightBrightness Get Backlight Brightness Value (0-255)
EApiVgaSetBacklightBrightness Set Backlight Brightness Value (0-255)


There are 2 available EEPROMs available on the TQ x86 Starterkits

  • 0 - Module EEPROM (0xA0 address on I2C bus)
  • 1 - Carrier EEPROM (0xAE address on I2C bus)

Function returns Storage Size and Block Length value, needed to calculate write block alignment and size for EApiStorageAreaWrite function.

EApiStorageAreaRead ID Offset Bytecnt
Datatype dec hex dec



Offset and ByteCnt parameters must be a multiple of Block Length value that is returned by EApiStorageCap function.

EApiStorageAreaWrite ID Offset Data
Datatype dec hex hex …. hex


The current frequency is defined in Windows registry:


100KHz are set as default frequency, the following frequencies are available for the primary CPLD I2C Bus:

  • 50KHz
  • 100KHz
  • 400KHz

After changing I2C frequency in Windows registry, Tq driver must be reset in Windows Device Manager:

- Open Windows Device Manager -> System Devices -> TqDriver
- Right Click on TqDriver and select "Disable" 
- Right click on TqDriver and select "Enable
EApiI2CWriteReadRaw bus_id i2c_addr string_to_write bytes_to_read
Datatype dec hex hex … hex dec

To ignore write operation: <string_to_write> = “”
To ignore read operation: <bytes_to_read> = 0


EApiI2CReadTransfer | EApiI2CWriteTransfer
EApiI2CReadTransfer bus_id i2c_addr cmd type bytes_to_read
EApiI2CWriteTransfer bus_id i2c_addr cmd type bytes_to_write
Datatype dec hex hex hex dec

where 'type' = 0/1/2 (No Command/ Standard Command/ Extended Command)



Delay mode is not supported. Event mode and Reset mode are supported.

List of possible Watchdog timeout values

If timeout falls between these values, the closest top value will be used: For Example:
For 10 seconds - 16 secnds will be used.
For 683 seconds - 1024 seconds will be used.

Event Mode

Event timeout must be defined, other Timeout values must be 0.
2 interrupt lines are supported: 10 and 11.
Default line is 11.
Interrupt number must be defined in 2 places:

  • Windows registry: HKLM\SYSTEM\CurrentControlSet\Services\TqDrv\Parameters\WdtInterrupt
  • TQ driver resources in Device Manager

To change IRQ line you need to change it in 2 places. After that you need to reset Tq driver in Windows Device Manager:

  • Open Windows Device Manager and find System Devices/ TqDriver
  • Right Click on TqDriver and choose “Disable”, then reenable it
Reset mode

Reset timeout must be defined, other Timeout values must be 0.
Following reset modes are supported:
1 = watchdog reset output triggers hard reset signal
0 = watchdog reset output triggers power-on button
Reset mode is definded in Windows Registry, default value is 1.

Dual-Stage Mode

In dual-stage mode (Event + Reset) Event timeout will be used for both stages. Event timeout must be defined, reset timeout must not equal zero.
EApiWDogStart <Delay> <EventTimeout> <ResetTimeout>
Time must be specified in ms.

EApiWDogStart 0 15200 1000

The number of GPIOs depends on the used module!

The EAPI library defines two different mechanisms to address GPIO: pin addressing and bank addressing.
Function EAPI_GPIO_BANK_ID(GPIO_NUM) is used to define the GPIO bank.


TqApp function EApiGPIOGetDirectionuses bank addressing.



EApiGPIOSetDirection <Pin> <Direction> uses pin addressing.

GPIO Direction Value
Output 0
Input 1

Setting pin 2 to output

> TqApp.exe EApiGPIOSetDirection 2 0

EApiGPIOSetLevel <bank> uses bank addressing, where <bank> is a group of 32 pins addressed simultaneously. Example:

> TqApp.exe EApiGPIOsetLevel 4 1

EApiGPIOGetLevel <bank> uses bank addressing, where <bank> is a group of 32 pins addressed simultaneously. Example:

> TqApp.exe EApiGPIOGetLevel 0
Bank 0: LEVEL = 0xfb


This function detects Watchdog interrupts, there is a standalone application for TqWdtWaitForInterrupt because it’s not part of EAPI.



  • I2C EEPROM may be unstable if I2C bus speed is set to 400KHz. Recommended I2C bus speed is 100KHz.
  • EEPROM access is unstable, e.g. when some data is written to I2C EERPOM it may get written to wrong offset. Usually it happens after large number (thousands) of successive write operations to the EEPROM, or while reading EEPROM in big chunks. Most likely it is a h/w issue of particular model of EEPROM.

Disable Windows Driver Signature Verification

1. Open Windows Command Promt with Admin rights
2. Enable “Test Mode”:

bcdedit /set testsigning on

3. Restart your System
4. After restarting, “Test Mode” should be displayed at the bottom right of the desktop. Now the TQ EAPI can be installed as described under EAPI installation.

5. After the installation the “Test Mode” can be terminated again:

bcdedit /set testsigning off

6. Reboot the system to apply the configuration

  • Last modified: 2023/05/02 07:19