Amontec Jtagkey-Tiny and Olimex SAM7-EX256

Development Boards MicroMod
1

Hi all.

I want to use the jtagkey-tiny from amontec together with the sam7-ex256 development board from olimex. For some reason I don’t manage to get it work:

Info:    openocd.c:92 main(): Open On-Chip Debugger (2007-07-31 19:00 CEST)
Error:   jtag.c:1346 jtag_validate_chain(): Error validating JTAG scan chain, IR mismatch, scan returned 0x3f
Error:   jtag.c:1346 jtag_validate_chain(): Error validating JTAG scan chain, IR mismatch, scan returned 0x3f
Error:   jtag.c:1346 jtag_validate_chain(): Error validating JTAG scan chain, IR mismatch, scan returned 0x3f
Error:   jtag.c:1346 jtag_validate_chain(): Error validating JTAG scan chain, IR mismatch, scan returned 0x3f
Error:   jtag.c:1346 jtag_validate_chain(): Error validating JTAG scan chain, IR mismatch, scan returned 0x3f
Error:   jtag.c:1346 jtag_validate_chain(): Error validating JTAG scan chain, IR mismatch, scan returned 0x3f
Error:   jtag.c:1442 jtag_init(): Could not validate JTAG chain, exit

I am a bit at a loss. The configuration file looks like this:

#daemon configuration
telnet_port 4444
gdb_port 3333

#interface
interface ft2232
ft2232_device_desc "Amontec JTAGkey"
ft2232_layout "jtagkey"
ft2232_vid_pid 0x0403 0xcff8

jtag_speed 0
jtag_nsrst_delay 200
jtag_ntrst_delay 200

#reset_config <signals> [combination] [trst_type] [srst_type]
reset_config srst_only

#jtag_device <IR length> <IR capture> <IR mask> <IDCODE instruction>
jtag_device 4 0x1 0xf 0xe

#daemon_startup <'attach'|'reset'>
daemon_startup reset

#target <type> <endianess> <reset_mode> <jtag#> [variant]
target arm7tdmi little reset_halt 0 arm7tdmi

#run_and_halt_time <target#> <time_in_ms>
run_and_halt_time 0 30

flash bank at91sam7 0 0 0 0 0

This is OpenOCD as in Debian Testing (r188?).

Any ideas what could be wrong?

Thanks,

Simon

2

Following up my own post…

Ok, this confuses me.

If I power the board (via USB or separate power supply) before connecting the jtagkey-tiny via USB everything works OK, if the jtagkey is connected before powering up the board it fails.

Huh??

Bye,

Simon

3

That’s unfortunate! Connecting the JTAG after applying power can damage the JTAG interface on the target chip, if you are unlucky. It’s quite rare, but I have known it happen.

Leon

4

leon_heller:
That’s unfortunate! Connecting the JTAG after applying power can damage the JTAG interface on the target chip, if you are unlucky. It’s quite rare, but I have known it happen.

Yeah, I absolutely hate the idea of powering up the board earlier than the JTAG-interface. But right now the other way usually fails and I am at a loss what to do instead.

(I hope it also helps that I of course do the “hot” connection on the USB side, not on the 20-pin connector…)

Bye,

Simon