RE: [uCsimm] Generic IO Ports

From: Steven Merrifield (
Date: Thu Jul 19 2001 - 19:07:47 EDT


Well first of all, there is a nice example in the uCsimm manual
to flash a LED. This is a good starting point. Secondly, read
the manual for the 68EZ328, specifically Section 7 - Parallel Ports.

The manual example shows how to setup a pin as an output.

I have attached a simple example to read a pin as an input. I use
this code to check for a jumper at power-on to setup the default
networking parameters which are stored in EEPROM.



  Default header is on PD6 (SIMM pin 16), and is normally high.
  If it is read as low, then the default conditions should be restored.

  sjm July 2001


#include <asm/MC68EZ328.h>

int main(void)

  PDSEL |= 0x40; /* bit 6 type = IO pin */
  PDDIR &= 0xBF; /* bit 6 direction = input */

  if (PDDATA & 0x40) /* if it's not == 0, then do not restore defaults */

  printf("Default header was detected - resetting default parameters\n");
  /* set default conditions here */

-----Original Message-----
From: James []
Sent: Friday, 20 July 2001 4:34
To: ''
Subject: [uCsimm] Generic IO Ports

        Can anyone give me a simple example of how to read and write to the
Generic IO Pins on the ucsimm. I have browsed some different source code to
try to determine how and so far I have been unsuccessful.

Thanks in advance.

James Kinney
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