RPi Pico SDK Support¶

Just to be very clear and concise: The following instructions are not required to use the Arduino IDE with any RP2040-based boards. These instructions pertain to using only Raspberry Pi’s Pico SDK for RP2040 based boards.

Prerequisite¶

Follow Raspberry Pi’s “Getting Started with Pico” document to setup a proper development environment on your host PC (the machine that will build your project). Notice that the setup instructions are a little different for building on a Windows PC.

Either set an environment variable named PICO_SDK_PATH that points to your local clone of the pico-sdk or put the pico-sdk next to the CirquePinnacle folder or next to the folder containing your project using the CirquePinnacle library:

path/to/github/repos/
    pico-sdk/
    CirquePinnacle/
    my_pinnacle_project/

Alternatively, the CirquePinnacle repository can be included into your project’s “lib” folder as a copy or git submodule. For more detail, see the below instructions to Incorporating CirquePinnacle library into your project.

Building the library examples for the Pico SDK¶

Each example imports a set of constants (DR_PIN, SS_PIN) from the examples/pico_sdk/defaultPins.h file. Default values for SPI pins (SCK, MOSI, MISO) and I2C pins (SDA & SCL) come from the Pico SDK repository’s pico-sdk/src/boards/include/boards/<board_name>.h files.

1. Create a “build” directory in the CirquePinnacle repository’s root directory and navigate to it:

   cd CirquePinnacle
   mkdir build
   cd build
   

2. Configure CMake for your desired build type and specific a RP2040-based board. This step uses the CMakeLists.txt file located in the CirquePinnacle/examples/pico_sdk directory.

   on Linux¶

   cmake ../examples/pico_sdk -DCMAKE_BUILD_TYPE=Release -DPICO_BOARD=pico
   

   Or if building on a Windows PC:

   on Windows¶

   cmake -G "NMake Makefiles" ../examples/pico_sdk -DCMAKE_BUILD_TYPE=Release -DPICO_BOARD=pico
   

   The supported RP2040-based boards are listed in header files in the Pico SDK repository’s pico-sdk/src/boards/include/boards/<board_name>.h files.

   If the -DPICO_BOARD option is not specified, then the Pico SDK will default to building for the Raspberry Pi Pico board.

   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.

   -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. This option is not specific to the examples, rather it can be specified in any Pico-SDK project that uses the CirquePinnacle library.

   -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. This option is not specific to the examples, rather it can be specified in any Pico-SDK project that uses the CirquePinnacle library.

3. Build the examples.

   cmake --build . --config Release
   

   Notice we specified the build type again using the --config option.

   Note

   note If you see an error stating “‘PICO_DEFAULT_SPI_SCK_PIN’ was not declared in this scope”, then it means the board you selected with the -DPICO_BOARD option (in step 2) does not have a default set of SPI pins defined for it. To workaround this error, see the below instructions to use different pins for the SPI bus.

   Warning

   If doing consecutive build attempts, it is strongly encouraged to delete all files in the build directory before re-attempting to build the project.

Incorporating CirquePinnacle library into your project¶

In order to use the CirquePinnacle library in your RP2040 based project:

1. Make a copy of the CirquePinnacle library in a “lib” directory located in your project’s root directory.

   path/to/my/project/
       lib/
           CirquePinnacle/
       src/
           CMakeLists.txt
           ...
   

   Alternatively, you can add the CirquePinnacle repository as a git submodule.

2. Include the root CMakeLists.txt file from the CirquePinnacle library in your project’s top-level CMakeLists.txt file (usually located in the “src” directory) after invoking the pico_sdk_init() function. The following snippet assumes that your project’s “src” directory is on the same level as the previously mentioned “lib” directory.

   # Pull in SDK (must be before `project()`)
   include(../lib/CirquePinnacle/src/cmake/pico_sdk_import.cmake)
   
   project(${projectName} C CXX ASM)
   
   # Initialize the Pico SDK
   pico_sdk_init()
   
   # must be done after `pico_sdk_init()`
   include(../lib/CirquePinnacle/src/CMakeLists.txt)
   

3. In the same CMakeLists.txt file (in your project) from step 2, add the CirquePinnacle library into the target_link_libraries configuration:

   target_link_libraries(${targetName}
       # ... Your project's other libraries ...
       CirquePinnacle
   )
   

   If you are using tinyUSB, this line (or similar) should already exist:

   target_include_directories(${targetName} PRIVATE ${CMAKE_CURRENT_LIST_DIR})
   

4. Finally, remember to include the necessary CirquePinnacle library’s header file in your project’s source code where applicable.

   #include <CirquePinnacle.h>
   

   Note

   Any of the project’s source file(s) that includes the CirquePinnacle library must be a C++ file. It is highly recommended to use the .cpp file extension for such project source files.

Using different pins for the SPI or I2C bus¶

Initially (without modification), the SPI and I2C bus uses the default pins defined in the Pico SDK repository’s pico-sdk/src/boards/include/boards/<board_name>.h files. However, there may be some boards that do not define the necessary pins to use as defaults. This can be remedied using either the Project Source code option or the Build-time configuration option.

Project Source code option¶

#include <CirquePinnacle.h>
PinnacleTouchSPI trackpad(DR_PIN, SS_PIN);
int main()
{
    // Using the pre-instantiated `SPI` object
    // Again, please review the GPIO pins' "Function Select Table" in the Pico SDK docs
    cirque_pinnacle_arduino_wrappers::SPI.begin(spi0, 2, 3, 4); // spi0 or spi1 bus, SCK, TX, RX

    if (!trackpad.begin(&cirque_pinnacle_arduino_wrappers::SPI)) {
        printf("Cirque Pinnacle not responding!\n");
    }
    // continue with program as normal ...
}

#include <CirquePinnacle.h>
PinnacleTouchI2C trackpad(DR_PIN);
int main()
{
    // Using the pre-instantiated `Wire` object.
    // Again, please review the GPIO pins' "Function Select Table" in the Pico SDK docs
    cirque_pinnacle_arduino_wrappers::Wire.begin(i2c0, 4, 5); // i2c0 or i2c1 bus, SDA, SCL

    if (!trackpad.begin(&cirque_pinnacle_arduino_wrappers::Wire)) {
        printf("Cirque Pinnacle not responding!\n");
    }
    // continue with program as normal ...
}

Build-time configuration option¶

To specify the default SPI or I2C pins used at build time, you can declare them in the CMakeLists.txt file.

target_compile_definitions(${CMAKE_PROJECT_NAME}
    PUBLIC PICO_DEFAULT_SPI=0 # can only be 0 or 1 (as in `spi0` or `spi1`)
    PUBLIC PICO_DEFAULT_SPI_SCK_PIN=2 # depends on which SPI bus (0 or 1) is being used
    PUBLIC PICO_DEFAULT_SPI_TX_PIN=3  # depends on which SPI bus (0 or 1) is being used
    PUBLIC PICO_DEFAULT_SPI_RX_PIN=4  # depends on which SPI bus (0 or 1) is being used
)

target_compile_definitions(${CMAKE_PROJECT_NAME}
    PUBLIC PICO_DEFAULT_I2C=0 # can only be 0 or 1 (as in `i2c0` or `i2c1`)
    PUBLIC PICO_DEFAULT_I2C_SCL_PIN=2 # depends on which I2C bus (0 or 1) is being used
    PUBLIC PICO_DEFAULT_I2C_SDA_PIN=3 # depends on which I2C bus (0 or 1) is being used
)

Using Multiple Cirque Pinnacle Trackpads¶

It is possible to drive multiple Cirque Pinnacle Trackpads on a single board. To do this, each trackpad needs dedicated digital output pins for the DR pin (and SS pin for SPI).

If you want to drive each trackpad with a separate SPI or I2C bus, then the following example will demonstrate how to do that.

#include <CirquePinnacle.h>

// Declare the pin numbers connected to the trackpads' DR and SS pins (respectively)
PinnacleTouchSPI trackpad0(DR_PIN_0, SS_PIN_0); // first trackpad object
PinnacleTouchSPI trackpad1(DR_PIN_1, SS_PIN_1); // second trackpad object

// By default, one SPI bus instance is created by the CirquePinnacle lib. We'll use this
// default instance of the `spi0` interface for our first trackpad, but we want a
// different SPI bus for the second trackpad.
//
// So, here we declare a second SPI bus instance:
cirque_pinnacle_arduino_wrappers::SPIClass my_spi; // we specify the `spi1` bus interface below

bool setupTrackpads()
{
    // Initialize the first trackpad using the default SPI instance
    if (!trackpad0.begin()) {
        printf("trackpad0 hardware is not responding!\n");
        return false;
    }
    // first trackpad object initialized successfully

    // specify the the second SPI bus interface and corresponding GPIO pins
    my_spi.begin(spi1, 26, 27, 28); // spi1 bus, SCK, TX, RX
    if (!trackpad1.begin(&my_spi)) {
        printf("trackpad1 hardware is not responding!\n");
        return false;
    }
    // second trackpad object initialized successfully
    return true;
}

int main()
{
    stdio_init_all(); // init necessary IO for the RP2040
    while (!setupTrackpads()) { // if either trackpadX.begin() failed
        sleep_ms(1000); // add 1 second delay for console readability
        // hold program in infinite attempts to initialize the trackpads
    }
    // continue with program as normal ...
}

#include <CirquePinnacle.h>

// Declare the pin numbers connected to the trackpads' DR and SS pins (respectively)
PinnacleTouchI2C trackpad0(DR_PIN_0); // first trackpad object
PinnacleTouchI2C trackpad1(DR_PIN_1); // second trackpad object

// By default, one I2C bus instance is created by the CirquePinnacle lib. We'll use this
// default instance of the `i2c0` interface for our first trackpad, but we want a
// different I2C bus for the second trackpad.
//
// So, here we declare a second I2C bus instance:
cirque_pinnacle_arduino_wrappers::TwoWire my_i2c; // we specify the `i2c1` bus interface below

bool setupTrackpads()
{
    // Initialize the first trackpad using the default I2C instance
    if (!trackpad0.begin()) {
        printf("trackpad0 hardware is not responding!\n");
        return false;
    }
    // first trackpad object initialized successfully

    // specify the the second I2C bus interface and corresponding GPIO pins
    my_i2c.begin(i2c1, 2, 3); // i2c1 bus, SDA, SCL
    if (!trackpad1.begin(&my_i2c)) {
        printf("trackpad1 hardware is not responding!\n");
        return false;
    }
    // second trackpad object initialized successfully
    return true;
}

int main()
{
    stdio_init_all(); // init necessary IO for the RP2040
    while (!setupTrackpads()) { // if either trackpadX.begin() failed
        sleep_ms(1000); // add 1 second delay for console readability
        // hold program in infinite attempts to initialize the trackpads
    }
    // continue with program as normal ...
}