[avr-chat] Cascading JTAG

[Matt.VanDeWerken]

Hi All:

Has anyone on this list successfully cascaded the JTAG ports of an
ATMega128 and an Altera device? I'm having trouble with it at the
moment, and I'm not sure whether the problem is with my dodgy hacked-up
cascade cable, the software (javr and quartus), the particular device
not supporting jtag fully (altera MAX7k, but actually need to know about
altera epc2), or the pinout I'm using.

The normal singly connected way is like this:

Byteblaster TDO <-> AVR TDO
AVR TDI <-> Byteblaster TDI

And also:

Byteblaster TDO <-> Altera TDO
Altera TDI <-> Byteblaster TDI 

This works, even though my nomenclature may be wrong (it should probably
be byteblaster TDO <-> AVR TDI etc). Anyway, using the same
nomenclature, I'm trying an altera byteblaster MV with the following
connection:

Byteblaster TDO <-> Altera TDO
Altera TDI <-> AVR TDO
AVR TDI <-> Byteblaster TDI

So, it should work, in theory. However, I get a jtag chain incomplete
error from both javr and quartus.

I'm going to try jtag from the openwince toolkit once I get my cygwin
installation fixed, but in the meantime I'd be happy to hear suggestions
on connection, cabling, or other things to try.

Cheers,
Matthew van de Werken - Electronics Engineer
CSIRO E&M - Rock Mass Characterisation - 1 Technology Court - Pullenvale
- 4069
p: (07) 3327 4142 * f: (07) 3327 4455 * e: address@hidden
"We do not inherit the earth from our ancestors, we borrow it from our
children." 
-- Native American Proverb