In SX Microcontrollers, SX/B Compiler and SX-Key Tool, mikegann wrote:

HI Mike - 

 

I see a couple of problems with your code. First is your shiftout commands you are using to configure the device:

 

' send the configuration bytes to the UART to set up for receiving MIDI input
   SHIFTOUT     UartOutputPin, UartClockPin, MSBFIRST, command1\8
   SHIFTOUT     UartOutputPin, UartClockPin, MSBFIRST, command2\8

 

You specify MSBFIRST, which is correct for the MAX3100. However you include the count parameter (\8) which forces the shiftout command to ignore the MSBFIRST and shift out the rightmost eight bits which  <SPAN style="FONT-SIZE: 10pt; COLOR: black; FONT-FAMILY: Verdana">effectively turns your shiftout comands to:

<SPAN style="FONT-SIZE: 10pt; COLOR: black; FONT-FAMILY: Verdana">SHIFTOUT     UartOutputPin, UartClockPin, LSBFIRST, command1

<SPAN style="FONT-SIZE: 10pt; COLOR: black; FONT-FAMILY: Verdana"><SPAN style="FONT-SIZE: 10pt; COLOR: black; FONT-FAMILY: Verdana">SHIFTOUT     UartOutputPin, UartClockPin, LSBFIRST, command2

 

Just remove the count parameter, it is not needed in your case.

 

The second problem is the way you are trying to read back the configuration. To write data to be transmitted or to read data which has been received you can use the shiftout / shiftin commands. To read the configuration of the MAX3100 you have to both write the command and read the data at the same time. To do this you can'y use the shiftin / shiftout commands.

 

I have attached a program that writes the configuration, then reads it back. Run it in debug and check the results. 

 

The code loop used to <SPAN style="FONT-SIZE: 10pt; COLOR: black; FONT-FAMILY: Verdana">simultaneously read and write the SPI data was found on this forum but I do not remember who wrote it to give proper credit.

 

I hope this helps.

 

Mike

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