SPI master problem, spi_read not working PIC16F887

[derrickbez]

I am communicating to an RFID reader using SPI. The reader is the Skyetek M9 and it is the SPI slave device. My PIC16F887 is the SPI master. After about a week I finally was able to get the M9 to transmit data back. The M9 starts every packet with a 0x02, and I can see that it is sending it using an Oscope. My problem is that I can not get the bytes coming in to save to memory. Please help, it seems like there should be a really easy solution. Code pasted below

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#include <16F887.h>

#FUSES INTRC,NOWDT,NOPUT,NOMCLR,NOPROTECT,NOCPD,NOBROWNOUT,NOIESO,NOFCMEN,NOLVP
#use delay(internal=4000000)
#use rs232(baud=38400, uart1, parity=N, bits=8, stop=1)

#define SSEL PIN_B0
#define D0 PIN_C5
#define DI PIN_C4
#define CLK PIN_C3

void main(void)
{
int i;
BYTE receive = 0;
setup_spi(SPI_MASTER | SPI_L_TO_H | SPI_CLK_DIV_16|SPI_SAMPLE_AT_END);
SET_TRIS_C(0x10); // bit 0 = output, 1 = input

while(1)
{
output_low(SSEL);
spi_write(0x02);
spi_write(0x00);
spi_write(0x0A);
spi_write(0x00);
spi_write(0x20);
spi_write(0x12);
spi_write(0x01);
spi_write(0x00);
spi_write(0x01);
spi_write(0x00);
spi_write(0x04);
spi_write(0xDA);
spi_write(0xE9);
output_high(SSEL); //Pull slave select high to indicate packet is done.

delay_ms( 8 );
for(i = 0; i<13; i++)
{
output_low(SSEL); //Pull Slave Select Low
receive = spi_read(0x00);
output_high(SSEL); //Pull Slave Select High

if (receive == 0x20 || receive == 0x08 || receive == 0x04 || receive == 0x02 || receive == 0x01 || receive == 0x10)
output_high(PIN_B2);
delay_ms( 3 );
}
delay_ms( 1000 );
}

}

[PCM programmer]

I can't find a data sheet for the M9 on their website. They have a
document that they call a "data sheet", but it's really a brochure.
If you know where they have the real data sheet available for download,
then post a link to it.

[derrickbez]

You have to have an account to access the data sheet. Here is all they say about the SPI:

*The M9 SPI interface communicates in Mode 1, which means that the clock polarity is zero and the clock phase is one.
*The host must implement SPI master functionality
*The SCK line should be the master clock controlled by the host.
*The MOSI signal provides data from the host to the SkyeModule M9.
*The MISO signal provides data from SkyeModule M9 to host.
*SSEL (Slave Select) is active low.
*The SPI master host software should keep the SCK pin at steady state low.
*Data is transmitted on the falling edge of SCK.
*The data packet exchange between the host (SPI Master) and the M9 (SPI Slave) uses SkyeTek Protocol v3 (Binary Mode only).
*The SPI connection is capable of a 4 MHz data rate.
*A ready signal indicates the reader has data for the host—in loop or inventory modes.
*Low = 0 to 0.8V; High = 2.0 to 5V

[PCM programmer]

[derrickbez]

Ok, I put both of those in after, just to see if they do anything. I have an LED set to light up if a 0x02 is ever received. Once it works i will save the data into an array as you have suggested.
I see the data coming in through the Oscope but it still does not save into memory.

[PCM programmer]

What is your compiler version ?

[derrickbez]

My compiler is version 4.020b.

Is there a way to ensure that the PIC is reading bits on the falling edge?

[ckielstra]

Double check you have 'data out' of the PIC connected to 'data in' of the M9 and vice versa.

What voltage is your PIC running?
What are the voltage levels you see on the scope?

[derrickbez]

Here is the data being received (MISO):
[img][/img]


Here is the data being sent (MOSI):
[img][/img]

The data is TTL and the voltages look ok to me (I have a pull up resistor on the receive pin of the PIC C4)

[derrickbez]

Actually the MISO pin is only showing 0 for low and 2 volts for high. All of my other pins are giving me 0 for low and 5V for high. Could this be the problem?

[ckielstra]

[derrickbez]

I just got it to work. I had an LED that was taking the voltage down.
Thank you for your time and your help.

working Code:

[PCM programmer]