Java SPI comm

[mitchellweb1]

Here is the SPI code that I have been working on for WPILibJ http://users.wpi.edu/~mwills/frc/ It is a little different than the current C implementation but I tried to make it so that it would be very easy to interact with multiple devices on the same SPI bus (the cRIO is only capable of one SPI bus). Please note that before you use the SPI device you must call SPIDevice.initBus (and you can call SPIDevice.freeBus to cleanup) with the clock, miso, and mosi pins.You can look at ADXL345_SPI.java for an example implementation of an SPIDevice (note this class does not contain the calls to initBus!). Please let me know if you get it working or have any problems or suggestions to improve the class. Eventually this code will be rolled into WPILibJ but it is still relatively untested.

--Mitchell

[Joe Ross]

Originally Posted by mitchellweb1

Here is the SPI code that I have been working on for WPILibJ http://users.wpi.edu/~mwills/frc/.

Thanks for working on this!

I've been playing with this code and had trouble with the chip select being short when I used a slower clock rate. I traced this to calling the following code after the transfer (in the transfer method)

            tSPI.writeChannels_SS_Module(0);
            tSPI.writeChannels_SS_Channel(0);

I commented it out and things are working. This might break if there are multiple devices on the bus, but I'm only using one. My problem might have been aggravated because I'm using a write only device and I had to remove the loop waiting for the read.

[Joe Ross]

Here's my updated SPIDevice class which is working for the LCD screen that I'm working with.

Changes (I also included a patch to Mitchel's version):
Don't read if writeOnly is true.
Add method for setting frame mode
fix typo in transferStatic method name
don't reset SS module and channel after transfer (fixes CS problem previously mentioned)