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Message

Trouble with JTAG

2005-11-22 by Howard Amos

I am using a mega32 with my own PCB (no JTAG socket). Started using an
ISP programmer (Avtiv8r from Meridian). In setting all the fuses I
disabled JTAG (had no use for it)...

How I have just bought an AVR JTAG ICE (from kanda.com) and want to
debug using JTAG.

My PORTC comes out to a 10 pin strip, so I make a cable to connect to
the JTAG cable on the ICE.

I turn on JTAGEN and OCDEN using the ISP programmer.

Trouble is, PortC.2 (TCLK) is OUTPUTTING a '1'. The ICE wants to drive
a '0'.

As I understand things, when JTAG is enabled, TCLK should be an input
to the AVR, so therefore I cannot have JTAG enabled.

So I stop and restart my ISP programmer, and READ the fuses. JTAGEN
and OCDEN are enabled (programmed), but TCLK is still an OUTPUT.

Any ideas.

Many thanks,

Howard Amos

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