IEEE-1284 Parallel port in ECP mode problems

IEEE-1284 Parallel port in ECP mode problems

Post by falst.. » Sat, 23 Aug 1997 04:00:00



Hi,

I'm developing a peripheral that is supposed to talk to a host PC (or other
desktop machine) over an IEEE-1284 compatible parallel port.  I've read
the standard and implemented all the handshaking required both in the host
and on a PIC microcontroller in the peripheral.
The host machine (a StrongARM RiscPC) uses an SMC 37C665 super-I/O controller
which is used in programmed-I/O mode since the DREQ is not connected.

When put into forward ECP mode I can write bytes to the data FIFO at offset
400, and they are transmitted to the peripheral (I'm watching the results
on a logic analyzer).  When the peripheral requests reverse channel, the
host negotiates that OK (in software), but when I put the 37C665 in what
I think is the correct mode, it fails to pick up the first byte (it doesn't
clock it in or generates handshaking signals on /AUTOFEED).

Anyone have a clue what is going wrong?

Thanks,
Frank
--
The famous GIICM now on line:  http://www.xs4all.nl/~falstaff/GIICM.html
------------------------------------------------------------------------
Frank A. Vorstenbosch   Wimbledon, London SW19   home: +44-(976)-430 569

 
 
 

IEEE-1284 Parallel port in ECP mode problems

Post by John Woodgat » Sat, 23 Aug 1997 04:00:00



>Hi,

>I'm developing a peripheral that is supposed to talk to a host PC (or other
>desktop machine) over an IEEE-1284 compatible parallel port.  I've read
>the standard and implemented all the handshaking required both in the host
>and on a PIC microcontroller in the peripheral.
>The host machine (a StrongARM RiscPC) uses an SMC 37C665 super-I/O controller
>which is used in programmed-I/O mode since the DREQ is not connected.

>When put into forward ECP mode I can write bytes to the data FIFO at offset
>400, and they are transmitted to the peripheral (I'm watching the results
>on a logic analyzer).  When the peripheral requests reverse channel, the
>host negotiates that OK (in software), but when I put the 37C665 in what
>I think is the correct mode, it fails to pick up the first byte (it doesn't
>clock it in or generates handshaking signals on /AUTOFEED).

>Anyone have a clue what is going wrong?

>Thanks,
>Frank
>--
>The famous GIICM now on line:  http://www.xs4all.nl/~falstaff/GIICM.html
>------------------------------------------------------------------------
>Frank A. Vorstenbosch   Wimbledon, London SW19   home: +44-(976)-430 569


Try posting to comp.sys.acorn.hardware or comp.sys.acorn.misc (if you
haven't already, and I don't think you have).
--
Regards, John Woodgate. Phone +44 (0)1268 747839
Fax +44 (0)1268 777124. OOO - Own Opinions Only
Elector of Rayleigh. Knight Grand Four-Cusped
Astroid of the First Order of Magnitude

 
 
 

IEEE-1284 Parallel port in ECP mode problems

Post by Kevin R Eva » Wed, 03 Sep 1997 04:00:00


You may want to try:

http://www.netos.com/LPT/

These folks do a lot of parallel port programming, they may be able to
help you.

Kevin


>Hi,

>I'm developing a peripheral that is supposed to talk to a host PC (or other
>desktop machine) over an IEEE-1284 compatible parallel port.  I've read
>the standard and implemented all the handshaking required both in the host
>and on a PIC microcontroller in the peripheral.
>The host machine (a StrongARM RiscPC) uses an SMC 37C665 super-I/O controller
>which is used in programmed-I/O mode since the DREQ is not connected.

>When put into forward ECP mode I can write bytes to the data FIFO at offset
>400, and they are transmitted to the peripheral (I'm watching the results
>on a logic analyzer).  When the peripheral requests reverse channel, the
>host negotiates that OK (in software), but when I put the 37C665 in what
>I think is the correct mode, it fails to pick up the first byte (it doesn't
>clock it in or generates handshaking signals on /AUTOFEED).

>Anyone have a clue what is going wrong?

>Thanks,
>Frank
>--
>The famous GIICM now on line:  http://www.xs4all.nl/~falstaff/GIICM.html
>------------------------------------------------------------------------
>Frank A. Vorstenbosch   Wimbledon, London SW19   home: +44-(976)-430 569