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The JTAG Interface of certain embedded processors can be used to debug the firmware running and to program new software. Most Jtag Interfaces are compatible to IEEE1149.1, but there are differences in the exact pin-out and supported voltages. Using an ICnova equipped with an ARM-processor, JTAG-adaptors with an 10- or 20-pins are common. Usally the JTAG-Interface is in use only, if the bootloader of a specific board must be modified or was overwritten accidentally.

10-pin JTAG-Adaptor

Certain programmers, eg the ICprog OpenOCD, can be used directly to interface the Board the board with by a straight 10-pin cable. This programmer is compatible to the OpenOCD project. Using other programmers, the exact pinout of the interface has to be checked.

20-pin JTAG-Adaptor

There are a lot of other programmers, which can be used to program the ARM-based ICnova modules. Most of them have a 20-pin interface. Before choosing one, it should be made sure, that the programmer can be accessed by the correct Software on the PC, eg. OpenOCD. The 20-pin connector can be adapted using the followin pinning scheme:

Pinout for 20-pin JTAG-Adaptor to ICnova
Signal 20 pin 10 pin
Vref 1 4
Vsupply 2 7
TRST 3 8
GND 4 2,10
TDI 5 9
GND 6 2,10
TMS 7 5
GND 8 2,10
TCK 9 1
GND 10 2,10
GND 12 2,10
TDO 13 3
GND 14 2,10
nRST 15 6
GND 16 2,10
NC 17 NC
GND 18 2,10
NC 19 NC
GND 20 2,10
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