JTAG

I'm trying to get use of JTAG for U-Boot debugging and probably FPGA debugging in the future. This page is not yet finished, and the work is in progress.

Building a JTAG connector for apf27Dev board

List of material and part numbers at Conrad:

• 2x20-pin header, 2.54mm pitch (Conrad: 741973)
• ATA/IDE cable (Conrad: 971742)
• 2x10-pin IDC low profile header, 2.54mm pitch (Conrad: 743534)
• 20-way flat cable, 1.27mm pitch (Conrad: 609463)

Assembling it all together:

1. Solder the 40-in header onto the J19 connector on the apf27dev board
2. Cut off a ~10cm piece from the ATA cable with the 40pin plug at the end.
3. Cut off ~10cm from 20-way flat cable
4. Carefully attach the 20-pin header to the flat cable. The thing is easy to break and it requires some forcing. Better buy a spare piece in advance.
5. Use a knife and a cutting pad and dissect the cable endings, ~3cm long. Dissect the whole width of the 20-way cable and only pins 40 to 31 on the 40-way ATA cable.
6. Strip the cable endings
7. Solder the two cables together, as specified below:

ARM JTAG 20-pin cable	apf27 J19 40-pin cable
1 - Vddh (+3.3v)	39
2 - Vddh (+3.3v)	39
3 - nTRST	33
4, 6, 8, 10, 12, 14, 16, 18, 20 - Vss (ground)	31, 34, 40
5 - TDI	35
7 - TMS	36
9  - TCK	37
13 –TDO	38
15 – nRST	---