Ok, this has to be a quirk of I2C that I'm not aware of, this is odd.

I'm using a PIC18F2320 to talk to a Matrix Orbital GLK12232-25SM LCD, It
has a 16C87 on it FYI.

I was having trouble talking to it so I thought I had the address wrong,
I wrote a loop to go though all possible addresses, and bingo it worked.
  So I binary searched til I found it, decimal 80, which was what I
thought it was in the first place.  So I took the loop out and tried to
talk to 80, no luck.  What the hell I say to myself. :)

So I play around a bit and find that if I try to send data to it without
first having tried to send data beforehand, ANY data, it won't work.
But if I just send 0x00 to address 0x00 (or anything to anything) it
works fine.

So I'm guessing it's some kind of reset condition on the I2C bus?  I set
SDA/SCL high before starting anything and that didn't seem to do
anything, maybe something in the PIC that gets setup after the first
run?  Seems odd but I'm out of ideas here! :)

Here's my code to illustrate if I'm doing something absurd:

--------- SNIP ------------
void init() {
   TRISC = 0b10000000; // See pinout

   SMP = 1; // Slew Rate Standard (100KHz - 1MHz)
   SSPADD = 19; // I2C clock = 8M/(4*(19+1)) -> 100KHz
   SSPCON1 = 0x08; // Master, clock from SSPADD
   SSPEN = 1; // Synch. Serial Port Enabled
}
void sendI2C(unsigned char addr, char* data, unsigned char len) {
   unsigned char i;

   SSPIF = 0; // Clear SSP flag
   SEN = 1; // Start Enable
   while(SEN); // Wait to finish
   SSPIF = 0; // Clear SSP flag
   SSPBUF = addr; // Send address
   while(!SSPIF); // Wait for SSPIF flag
   SSPIF = 0; // Clear SSP flag
   for(i = 0; i < len; i++) {
     SSPBUF = data[i]; // Send data
     while(!SSPIF); // Wait for SSPIF flag
     SSPIF = 0; // Clear SSP flag
   }
   PEN = 1;
   while(PEN); // Wait to finish
   SSPIF = 0; // Clear SSP flag

   delayMilliseconds(1);
}

void sendStuff() {
   char data[] = { 0xFE, 0x62, 2, 0, 0 };
   char len = 5;

   sendI2C(80, data, len);
   sendI2C(80, data, len);
}

void main() {
   init(); // setup ports, registers, etc...

   delaySeconds(2); // wait for everyone to wake up
   sendStuff();

   while(1);
}
------------- SNIP --------------

This works.  If I change sendStuff() to have just 1 sendI2C, it doesn't
work.  Any suggestions are appreciated on the code as well of course.

Thanks!

Nick

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