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[avr-gcc-list] Announcing parallel port JTAG code

From: Torsten Mohr
Subject: [avr-gcc-list] Announcing parallel port JTAG code
Date: Thu, 5 Dec 2002 17:22:47 +0100
User-agent: KMail/1.4.3

Hi everybody,

i just wrote some code to access the parallel port (at the moment
it's Linux only).

With that code you can access several things connected to the
parallel port:
- several serial EEPROMs (24cXX, 93x6, M95xxx).
- debug an ARM core (works at least for my AT91M40400 EB01).
- terminal connection to an AVRs SPI.

The code consists of several libraries, there's:

libpppcb.a that lets you access the parallel port and lets
you set/clear single pins and read pins back.

libpppcb_jtag.a that provides some basic JTAG functions,
like handle all the TAP states and shift IR/DR.

libpppcb_armdebug.a that lets you read/write memory/registers,
start at a certain address, stop/resume program execution, ...

libpppcb_avr.a at the moment only lets you generate a reset
and the SPI can be polled for data, but the JTAG code that
already works for ARM may help to debug an AVR, when the
appropriate infos about the registers are available.
Also, the SPI communication seems to be a bit buggy at the

The libraries support different pinnings, you can e.g. specify
different pins for TMS, TCK, TDI, TDO, ...

You can also specify different polarities for single pins.

The code can be downloaded directly here:


There are sure some more things to do, especially some

Best regards,

avr-gcc-list at http://avr1.org

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