4 Replies Latest reply on Jan 21, 2015 2:53 PM by userc_7511

    Having Trouble with P38 I/O on BCM20736S Module

      I'm trying to use P38 on the BCM20736S module and it's not working.  I have a custom board with the 736S module and a TAG development board with a 737 chip.  My code for putting output on P38 works on the TAG board but not on my custom board.  I have done this experiment using P38 as a SPI MOSI and as a GPIO output.  Both work on the TAG but neither work on my 736S board.  I know P38 is paired/bonded with P14 and I have disabled P14.   On the other hand P04 works both as MOSI and GPIO Output on my 736S module.  My SPI code works on the TAG board and it is based on the sample code in the documentation.  I have looked for conflicts and don't see any, pUART or otherwise.  My code is based on the Heart Rate Monitor App.

       

      Is there something I should know about P38 that is not in the documentation?  I could switch to P04 but that means the entire design goes back to the drawing board and a new layout and PCB version, so I would like to use P38 for MOSI if possible.

       

      p.s. I do see SCLK coming out on P24 when I transmit data via SPIFFY2 Master... but nothing comes out on P38 which is configured as MOSI.  Again, the exact same code works fine on the TAG board where I see both SCLK and MOSI on the scope.

       

      Thanks for any suggestions.

      Eric