JTAG-Pogrammer with target isolation
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This is a JTAG-Programmer developed by the Robot Soccer Team ER-Force from Erlangen, Germany. The device is using a FTDI chip for communication and a digital isolator for the target. All necessary files to build and control this device can be found within this repository.

The benefits of this hardware are the easy USB connection with EMC protection and over-current protection. Furthermore the standard JTAG output with a complete isolation up to 4kV. The target isolation is done by two ISO7231M from Texas Instruments. This device also does a voltage translation, which adapts to the target voltage-level. Working is guaranteed from 3.2 to 5.4V. With this circuit the computer is never effected, if the programming target fails in any way.

Project origin: https://www.robotics-erlangen.de/publications/jtag-programmer


The PCB is designed with EAGLE. The schematic can be found in erprog_1504-1.sch and the board in erprog_1504-1.brd. The dimension of the PCB is 850mil x 2300mil.

The main ICs are

  1. FT4232HL does the USB to JTAG conversation
  2. ISO7231 is the digital isolator


The software readme is in https://github.com/robotics-erlangen/erprog/tree/master/software

Computer connection

via USB

The device is connected via a Mini-USB plug to the computer.

Target connection

via JTAG

This hardware uses a JTAG standard connector with a 10 pin connector with the CoreSight 10 pinout. Follwoing the pinout is described based on a standard 10 pin 100mil plug with 2 rows.

  1. VTREF
  2. TMS
  3. GND
  4. TCK
  5. GND
  6. TDO
  7. NC
  8. TDI
  9. GND
  10. nSRST


For the next release it is planned to allow the controlling of the isolator's enable-pin. Thus, the programmer can be put into high-impedance mode so it does not interfere with the target in normal operation.