Re: [avr-gcc-list] Strike that

[Theodore A. Roth]

On Thu, 13 Nov 2003, Brian Cuthie wrote:

>
> Ah, it appears, actually, that I'm not writing anything.
>
> Things here have gotten really weird. The JTAG interface doesn't seem to
> be working correctly with my board. Studio 3.56 will find it, Studio 4
> says it can't connect to the JTAG interface. gdb sometimes gets E01 and
> fails, then avarice quits.

What MCU clock frequency are you running your device at? You must run
the jtag clock bitrate no faster than 1/4 of the MCU clock freq.

If you try to run the jtag bitrate too high, you will see the E01 errors
in gdb. Basically, the jtagice box fails to read/write/control the
device and avarice just passes the error up to gdb.

I recently added a -B option to avarice to allow slowing down the jtag
bitrate. Avarice defaults to 1MHz bitrate which will fail to work
reliably with devices as shipped by Atmel. All the jtag capable mega's
I've seen are prefused by Atmel to use the 1MHz internal ocsilator, so
you would need to drop the jtag bitrate to 250 KHz max or set the fuses
to use another clock source.

Ted Roth