JTAG Adapter – ARM 10-pin <---> ARM 20-pin

We’ve got a new microcontroller board, which got a 10-pin JTAG interface for external debugging. The problem was that we just owned a J-Link EDU, which got a 20-pin JTAG interface. We needed an adapter between the 10-pin and the 20-pin JTAG.

Adapter

Schematic

  • VCC … Voltage Common Collector
  • GND … Ground
  • TMS … Test Mode Select
  • TCK … Test Clock
  • TDO … Test Data Out
  • TDI … Test Data In
  • RST … Reset
 Physical

  • 2.54mm single sided perforated board
  • 10×2 2.54mm straight male box header
  • 10-pin 1.27mm ribbon cable
  • 5×2 1.27mm straight female box header 1

(1) I used a 10×2 1.27mm str. fem. box header

Connection

Desktop-PC/Laptop [USB A (♀)] <--- USB cable ---> [USB B (♀)] J-Link
J-Link [JTAG 20-pin (♂)] <--- Ribbon cable 20-pin ---> [JTAG 20-pin (♂)] Adapter
Adapter [JTAG 10-pin (♀)] <---> [JTAG 10-pin (♂)] Microcontroller board

Debugging

  1. J-Link GDB Server
    1. Execute (on PC)
    2. Configure (e.g Target, Protocol)
    3. Start
  2. GDB
    1. Execute (on PC)
    2. Set Binary
    3. Connect and Load
    4. Debug