SPI Problems

Rabbit
1

Hi,

I m working with this RCM4500 and using this SPI function but it didint seen to work. i read some of the post and notice that the comment was to us Serial B instead of serial C. but i have already use Serial B for my xbee.

Was serial C not competible for SPI? i used and edited they sample coding given:

#class auto

#define SPI_SER_C
#define SPI_CLK_DIVISOR 100

#use “spi.lib”

void main()
{
char adc_reading[2];
int i;
int adc_sample;

SPIinit();
while(1)
{
            SPIWrite("\x05", 1);   \\ cmd to write to register
   SPIRead(adc_reading, 2);
   printf("SPI bytes = 0x%x 0x%x

", adc_reading[0], adc_reading[1]);
}
}

I always got a 0xff or 0x00

Or is my pin configuration wrong? Below is my configuration:

PC3 connected to Dout of my SPI component
PC2 connected to Din of my SPI component
PD2 connected to SCLK of my SPI component

2

What about chip select? I’ve got some devices here that will not work if you just ground /CS…

Haven’t used SPI.LIB myself - I just roll my own - so I can’t speak to that aspect of it. I do use serial port C as an SPI port though (this is on an RCM 5700, not 4500), so there should be no problem there.

Another thing to look at: You haven’t shown your port initialization. Have you set up Serial Port C to map to the pins you are using?

3

Whyd you need to throw in the part about telling Mike you wouldnt post about this then turn around and did just that?

Ive not had any problems.

4

Thanks for your quite respond. Initalising? To do u mean this?

#define SPI_DR	SCDR
#define SPI_CR	SCCR
#define SPI_ShCR	SCCRShadow
#define SPI_SR	SCSR
#define SPI_ER	SCER
#define SPI_ShER	SCERShadow

WrPortI ( SCDHR, NULL, (SPIdivisor>>8) | 0x80 );
WrPortI ( SCDLR, NULL,  SPIdivisor & 0xFF );

its defined in the spi library.
Ok i will connect tthe chipselect and see if it works.

5

By initializing, I’m referring to setting up the parallel ports. Like this, which won’t be exactly what you need to do, but should give you the idea:


   // Parallel Port C Setup
   WrPortI(PCDDR, &PCDDRShadow, (PCDDRShadow & 0xF3) | 0x0C);   // PC2 & 3 are outputs
   WrPortI(PCALR, &PCALRShadow, (PCALRShadow & 0xCF) | 0x00);   // PC2: Alt out 0 (TxC)
   WrPortI(PCFR,  &PCFRShadow,  (PCFRShadow  & 0xF3) | 0x04);   // PC2 alt out, PC3 norm

   // Parallel Port D Setup
   WrPortI(PDDDR, &PDDDRShadow, (PDDDRShadow & 0xF3) | 0x0C);  // PD2, 3 are outputs
   WrPortI(PDALR, &PDALRShadow, (PDALRShadow & 0xCF) | 0x00);  // PD2: Alt out 0 (SCLKC)
   WrPortI(PDFR,  &PDFRShadow,  (PDFRShadow  & 0xF3) | 0x04);  // PD2 alt out, PD3 norm

The registers are described in the Microprocessor User’s Manual for whatever processor you are using.

6

Hi, im also trying out the spi in rabbit, im trying to connect it with a adc, so basically what pins do i need to wired out to the rabbits port…

Vcc to +3.3V
Gnd to Gnd
SCLK to SCLKA
Chip Selection to Any Output Port
Data out to TxB
Data In to RxB

is it something like this?