I am having trouble trying to get the SPI port working on an MC9S12DG128 (80 pin variant). Previously, I have used the MC9S12C128 processor (48 pin variant), and used the SPI port with no problems. Basically, I have tried to use the same initialization and operational code on both processors. Both processors are using an 8MHz oscillator, and the initialization code is as follows:
SPI0CR1 = 0x50;
SPI0CR2 = 0x00; // normal mode
SPI0BR = 0x04; // 24MHz/32=750kHz
My SPI routines are:
void SPIOut(unsigned short usCode)
{
PTM &= ~0x08; // PM3=chip select=0
SendSPI(usCode>>8); // msbyte (command)
SendSPI(usCode); // lsbyte (data)
PTM |= 0x08; // PM3=chip select=1
}
void SendSPI(unsigned char ucCode)
{
unsigned char ucDummy;
while((SPI0SR & 0x20)==0){}; // wait SPTEF
SPI0DR = ucCode; // data out
while((SPI0SR & 0x80)==0){}; // wait SPIF
ucDummy = SPI0DR; // clear SPIF
}
As you can see, I manually toggle the SS pin for each data transfer.
In terms of connections, I am using the following pins:
70 PM5/SCK0
71 PM4/MOSI0
72 PM3/SS0
73 PM2/MISO0
Is there some subtle difference between the two processors that I'm not aware of? Any help with this would be gratefully appreciated.
