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songyang

Beginner

Date of registration: Feb 4th 2011

Posts: 1

1

Friday, February 4th 2011, 9:47am

j-link doesn't work

:huh: when i use j-link v6 in keil for debuging atsam9g20, it display

**JLink Error: Bad JTAG communication: Write to IR: Expected 0x1, got 0x7 (TAP Command : 2) @ Off 0x5.
___^
*** error 122: AGDI: memory read failed (0xFFFFFFF0)

but a few days ago, i have use j-link v8 for debugging and it works.what's the reason?

SEGGER - Alex

Super Moderator

Date of registration: Dec 18th 2007

Posts: 1,516

2

Wednesday, February 9th 2011, 5:50pm

Hi,

what J-Link speed do you use?
Since the AT91SAM9G20 is based on a ARM926EJ-S core, we recommend to use adaptive clocking instead of fixed JTAG speeds.
When using fixed speeds, the max. JTAG speed that can be used is 1/8 - 1/6 of the CPU speed (but with adaptive clocking you are always on the safe side).

If you are using a fixed JTAG speed:
To exclude that it was some kind of "luck in timing" that communication with your device worked with J-Link V8 and with J-Link V6 is does not,
please try again with adaptive speed.


Best regards
Alex