Linux Support¶

This library can be used on any Linux device that exposes GPIO pins.

Automated install script¶

There is a file named install-linux.sh that automates the process outlined in Installing from Source section. To use this script the file permission must be modified (only once):

chmod u+x install-linux.sh

Now you can run the script and follow the prompts:

./install-linux.sh

Installing from Source¶

1. Building the library from the source code requires CMake.

   on Linux¶

   sudo apt install cmake
   

2. Clone the repository:

   git clone https://github.com/2bndy5/CirquePinnacle.git
   

3. Navigate into the repository folder and create a build folder. Then navigate into the build folder.

   cd CirquePinnacle
   mkdir build && cd build
   

4. Configure CMake to build the library:

   cmake ../src -DPINNACLE_DRIVER=linux_kernel
   

   The -DPINNACLE_DRIVER will force the build to use 1 of the supported hardware drivers. This can also be specified using an environment variable named PINNACLE_DRIVER. With out this specified, CMake will look for required dependencies and use the first driver found. Supported options include (in order of precedence):

   • bcm2xxx is a bit slower and only works on RPi boards (requires sudo permission to execute).

   • pigpio requires the PiGPIO library installed (requires sudo permission to execute).

   • mraa requires the MRAA library installed.

   • linux_kernel (default fallback) is recommended for best user experience and cross-platform/architecture compatibility.

   Optional arguments

   -DPINNACLE_SPI_SPEED=6000000

   The SPI speed can be set with -DPINNACLE_SPI_SPEED=xxx to lower the default speed/baudrate used on the SPI bus. Default value is the officially recommended 6 MHz; maximum supported is 13 MHz.

   -DPINNACLE_ANYMEAS_SUPPORT=OFF

   To reduce the compile size of the CirquePinnacle library, you can use -DPINNACLE_ANYMEAS_SUPPORT=OFF when the application won’t use the Pinnacle’s anymeas mode.

5. Build and install the library:

   make
   sudo make install
   

Run an example¶

After the library is installed, open one of the linux examples (located in examples/linux) and change the pin numbers accordingly. The following steps will use a build folder created in the CirquePinnacle repository’s root folder (as created in step 3 above).

1. First make sure the created build folder is empty.

   Be sure to do this from within the build folder!!! ¶

   rm -r ./*
   

2. Configure CMake to build the examples:

   cmake ../examples/linux -DPINNACLE_DRIVER=linux_kernel
   

   Again, specify the driver used to build the library (see step 4 above) is recommended because some drivers require the built applications to be linked to pre-installed libraries.

   Optional arguments

   -DUSE_I2C=ON

   If using the I2C interface (PinnacleTouchI2C), then you can enable this for the examples with -DUSE_I2C=ON.

   -DUSE_SW_DR=ON

   If not using a physical GPIO pin for the Data Ready pin, then you can use -DUSE_SW_DR=ON which will automatically make the examples use PINNACLE_SW_DR value for the dataReadyPin parameters to the PinnacleTouchSPI() and PinnacleTouchI2C() constructors. The anymeas_mode example is automatically excluded from the build targets since it requires a hardware Data Ready pin.

3. Build the examples:

   make
   

4. Run an example:

   ./relative_mode
   

   Remember that both PINNACLE_DRIVERs bcm2xxx and pigpio will require sudo permission.

SlaveSelect pin¶

Using the SPI bus’ SS pin (Slave Select, aka Chip Select) on a Linux platform is a bit different from the Arduino platform because the Linux kernel controls the pin during bus transactions. Therefore, the pin number passed to the PinnacleTouchSPI() constructor should follow the form ab where a is the SPI bus number and b is the specified bus’ SS pin (often labeled CE<b> on Raspberry Pi pinout diagrams).

Using a non-default I2C bus¶

The default I2C bus used is /dev/i2c-1. However, some boards may use a different I2C bus number as a default. This can be remedied by passing the correct bus number to cirque_pinnacle_arduino_wrappers::TwoWire::begin().

#include <CirquePinnacle.h>
#define DR_PIN 25
PinnacleTouchI2C trackpad(DR_PIN);

int main() {
    // specify the I2C bus
    cirque_pinnacle_arduino_wrappers::Wire.begin(0); // (1)!

    if (!trackpad.begin(&cirque_pinnacle_arduino_wrappers::Wire)) { // (2)!
        return 1; // failed to initialize the trackpad
    }
    // continue the program as usual ...
}