Atmel PLD JTAG cable (slightly off topic)

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ampz
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Posted by ampz: Mon. Sep 23, 2002 - 04:34 AM
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Not AVR's but at least it's atmel..
I'am looking for the schematics/pinout for Atmel's PLD ISP cable (JTAG) used for ATF15xxx PLD's.
Might be the same cable as for JTAG capable AVR's?

The entire PLD development kit is $100, and I only need the cable, not the demo board, nor the PLCC PLD's that comes with it.
Also, it looks like the needed software is freeware.

Tags:

AVR Microcontrollers, megaAVR and tinyAVR
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deoxy
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Posted by deoxy: Tue. Sep 24, 2002 - 07:23 PM
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I've used the ATF15xxx CPLDs before, and I made my own cable. Search the net for the Altera Byteblaster cable, which is pretty much a standard. Atmel's Jtag programming software includes support for the Byteblaster and Byteblaster MV (multiple voltages - supports 3.3v and 5v). It's a simple device, consisting of an 8-bit buffer, and some resistors. I'd imagine that you can replace the buffer with just resistors as I've seen done before, the buffer is there to protect your parallel port in case you accidently connect up to some wrong voltages.

I haven't tried the cable with an AVR, but I'd imagine it works, as long as the Atmel programming software supports that cable. Let me know what you find out.

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Silver Markadmin
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Posted by admin: Fri. Nov 8, 2002 - 11:51 AM
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For some strange reason the PLD JTAG interface is free (and works with cheap cable) and for the AVR the JTAG interface is only suported using an expencive convertor called JTAG ICE. It's defently not the TAP you pay for (because there are various programs available for the byteblaster cable, capable of programing / testing lots of JTAG devices. It seems the protected On Chip Debug commands are only sold for a lot of mony.

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dwb240
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Posted by dwb240: Fri. Nov 8, 2002 - 01:30 PM
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Hi,

I've got the CPLD dev board, and yeah the cable is basically the same. FYI go to page 45 of the user guide for the CPLD dev system:
http://www.atmel.com/atmel/acrob...

It's got the exact schematic there.

-Colin

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rh
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Posted by rh: Fri. Nov 8, 2002 - 05:58 PM
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hi,

yes, there are only a few JTAG commands for JTAG debugging AVRs.
But it makes no sense to do this with the commonly used printer port
interface called "Byteblaster" because AVR JTAG debugging needs
thousands of bit movements over the JTAG interface with the JTAG
protocol to do a byte read or write. You need a very fast boolean
machine (>=16MHz AVR etc) to get results in an acceptable time.

rh

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