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TXT firmware >= 4.4.3 needed!

TXT C Download Examples

TXT Programming

The fischertechnik TXT controller has an (embedded) Linux system that allows communication via WLAN, Bluetooth or USB interface. The network protocol is used for control by means of interfaces and the TXT can thus be directly activated via IP addresses.

In the previous Robo interface, it was important to know whether the interface was connected to the computer via the serial interface or the USB interface and the programming varied accordingly. In TXT, this differentiation has been done away with using the network protocol. Every interface of the TXT (USB, BT, WLAN) has a separate IP address. This makes the different programs more convenient and only the desired IP address must be used.

The sensors and actuators of the fischertechnik TXT controller can be controlled in two ways:

  • Online programming Here, a computer can control a controller via the USB cable, WLAN or Bluetooth (BT). The documentation can be found in txt_demo_c_online.

  • Download programming Here, a program is created with a cross compiler and transferred to the TXT, and it can be started there via the menu system. This documentation shows how an eclipse development environment can be used to create C download programs for the TXT. You can also use other IDE, e. g. Visual Studio or CodeLite.

Overview of the Demo Programs

There are several sample programs that explain the control of the TXT.

The basic C program in download mode looks as following:

#include "KeLibTxtDl.h"     // TXT Lib
#include "FtShmem.h"        // TXT Transfer Area

// Common debugging stuff for RoboProLib
unsigned int DebugFlags;
FILE *DebugFile;

int main(void) 
	if (StartTxtDownloadProg() == KELIB_ERROR_NONE)
		pTArea = GetKeLibTransferAreaMainAddress();
		if (pTArea)
	return 0;


The demo program prints "TXT: Hello World!" to cout.


The demo program prints analog value to cout.

Master TXT:

  • Input I1: Voltage or color sensor


The demo program shows the distance operation of the encoder motor. It is recommended that you plug a rest gear wheel 137677 to the axle and highlight a wheel. The program switches the motor for 2 rotations, then waits for a second and carries out the same number of rotations in the opposite direction. Then the program ends.

Master TXT:

  • Output M1 Encoder motor
  • Input C1 Counter signal of the encoder motor


The demo program shows the initialisation of the universal inputs and then requests them for 10 seconds. If the key is pressed, the M1 motor is switched on. The measured distance value of the ultrasonic sensor controls the M2 motor in the 0..100 cm area with a proportional speed. The program automatically ends after 10 seconds.

Master TXT:

  • Input I1 key
  • Input I2 Ultrasonic sensor (if present)
  • Output M1 Light or motor
  • Output M2 Light or motor

Extension TXT (Connect Extension only if a second TXT is present.):

  • Input I1 key
  • Input I2 Ultrasonic sensor (if present)
  • Output M1 Light or motor
  • Output M2 Light or motor


This example shows the data output at the I2C bus. The I2C unit must first be initialised, and the I2C function can then be used to write the desired number of bytes and then read in the response.

Master TXT:

  • I1: Switch
  • I2C: PCF8574 with LED's on the Outputs


The demo program shows the use of CallBack routine. As long as this function is set up, it is called up during the data exchange with the hardware after the inputs are read in and the output information is output.

The CallBack routine should not need a lot of time so that the timing is not affected. During the routine, the key - in order to show it as an example - is debounced and the motor is then switched depending on the input.

The program ends after the key is pressed 10 times at the I1 input.

Master TXT:

  • Input I1 key
  • Output M1 Light or motor


Eclipse IDE

Download and install:

TXT Tool Chain (TXT firmware >= 4.4.3)


Setting up Eclipse IDE

  1. Clone demo examples from GIT repository to a workspace folder.
  2. Start Eclipse CDT and import the examples to your workspace eclipse_import1 eclipse_import2
  3. Change 'Current builder' to 'CDT Internal Builder' in Release and Debug configuration eclipse_toolchain
  4. Change 'Prefix' and 'Path' to the tool chain location eclipse_tool_settings
  5. Change project properties in 'Paths and Symbols' eclipse_pathsandsymbols_includes eclipse_pathsandsymbols_libpaths eclipse_pathsandsymbols_libs

Downloading Programs to TXT

Compiled programs can be downloaded to the TXT controller using WinSCP

Attention: At first activate SSH Daemon for TXT firmware >=4.4.4!

  • Activate SSH Daemon on TXT controller


  • Login with ROBOPro user


  • Create the directory /opt/knobloch/DownloadFiles/


  • Copy the program binary using WinSCP to the path /opt/knobloch/DownloadFiles/. You can drag and drop files to the DownloadFiles directory

  • Set access rights in Properties of the downloaded binary


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