Need help with MCP23S08

[Christopher4187]

Only one thread on the 23S08. Well, maybe someone can help.

I believe my problem is in the hardware but if someone can check the command below, that would be great. I took the attached file in the first thread and believe only the write command needed to be changed. I modified it to this but I still get nothing out of the 23S08. I'm using the PICkit serial SPI board.

MCP_WRITE:
low CS
SSPBUF=0
GOSUB CLOCK_BIT
SSPBUF = spout
high CS
return

I feel like something is missing in there. Also, to rule out the board, I was toggling one pin at a time. When I toggle the MOSI or MISO pins, the both appear to be connected because both pins go high and low at the same time. In other words, I pulse the MOSI with a 2 Hz signal and the MISO pin appears to be in parallel.

Confused....

[Darrel Taylor]

After loading SSPBUF the second time, you need to wait for it to finish the transfer before taking CS high again.

[Christopher4187]

No dice. I think that command was wrong and this one *looks* correct after doing some more reading.

MCP_WRITE:
    low CS
    SSPBUF=64
    GOSUB CLOCK_BIT
    SSPBUF=MCP_ADDRESS
    GOSUB CLOCK_BIT
    SSPBUF = MCP_DATA
    GOSUB CLOCK_BIT                      
    high CS
return

Maybe one of the IC's on the PICkit board is bad. I wouldn't expect, although I don't know for sure, the MOSI and MISO pins to both go high or low at the same time if you only have power on one of those pins.

[gadelhas]

Hi Christopher;

Check this wiki article. It shows how to handle the MCP23S17. Maybe can help you if you adapt to your ic.
http://www.picbasic.co.uk/forum/cont...P-PBP-MSSP-ASM