Include bcm2853 lib on Raspberry Pi

Question

I want to start SPI communication with C# on my Raspberry. The bcm2835 lib supports the needed commands like:

• bcm2835_spi_begin()
• bcm2835_spi_end()
• etc.

In C you have to #include < bcm2835.h > but in C# using bcm2835; does not work.

RaspberryPiDotNet is installed and the bcm2835 library aswell.

The GPIO Pins can be controlled with the GPIOMem command which uses the bcm2835 library.

How can C# use the SPI commands of bcm2835 ? Everything on the net is for C or C++.

Answer 1

How to get SPI working with C# on the Raspberry Pi

Here is a complete Tutorial how to get it to work:

1. Install Mono:

   sudo apt-get update
   sudo apt-get install mono-complete
   

2. Install RaspberryPiDotNet:

   mkdir gpio_csharp
   git clone git://github.com/cypherkey/RaspberryPi.Net.git
   cd RaspberryPi.Net/RaspberryPiDotNet
   xbuild RaspberryPiDotNet.csproj
   cp bin/Debug/RaspberryPiDotNet.dll /home/pi/gpio_csharp/
   

3. Install bcm2835 library:

   wget http://www.airspayce.com/mikem/bcm2835/bcm2835-1.36.tar.gz
   tar -zxf bcm2835-1.36.tar.gz
   cd bcm2835-1.36
   ./configure
   make
   sudo make check
   sudo make install
   cd src
   cc - shared bcm2835.o -o libbcm2835.so
   cp libbcm2835.so /home/pi/gpio_csharp/
   

4. Delete unused files and folders:
   With this command you can delete the created folders and files but do not delete the "gpio_csharp":

   rm -r <folder>
   rm <file>
   

5. Create a C# script:

   nano /home/pi/gpio_csharp/xxxxx.cs   //xxxxx is your filename
   CTRL + X     //For exit and save script
   

6. Add SPI commands in the script:
   (Add this in the "class" space of the programm)

   [DllImport("libbcm2835.so", EntryPoint = "bcm2835_spi_begin")]
   static extern void spi_begin();
   
   [DllImport("libbcm2835.so", EntryPoint = "bcm2835_spi_end")]
   static extern void spi_end();
   
   [DllImport("libbcm2835.so", EntryPoint = "bcm2835_spi_transfer")]
   static extern byte spi_transfer(byte val);
   
   [DllImport("libbcm2835.so", EntryPoint = "bcm2835_spi_chipSelect")]
   static extern byte spi_chipSelect(GPIOPins pin);
   
   [DllImport("libbcm2835.so", EntryPoint = "bcm2835_spi_setClockDivider")]
   static extern byte spi_setClockDivider(int val);
   
   [DllImport("libbcm2835.so", EntryPoint = "bcm2835_spi_setDataMode")]
   static extern byte spi_setDataMode(int val);
   
   [DllImport("libbcm2835.so", EntryPoint = "bcm2835_spi_setChipSelectPolarity")]
   static extern byte spi_setChipSelectPolarity(GPIOPins pin, bool activeHigh);
   

7. Use commands in your code:
   Now you can use the following commands to use SPI. Example is down the page.

    spi_begin();
    spi_end();
    spi_transfer();
    spi_chipSelect();
    spi_setClockDivider();
    spi_setDataMode();
    spi_setChipSelectPolarity();
   

   
   Example:

       //SPI Try
       spi_setClockDivider(128);
       spi_setDataMode(0);
       spi_chipSelect(cs);
       spi_setChipSelectPolarity(cs, false);
       spi_begin();
       spi_transfer(0xAA);
       spi_end();