mbed API for Raspberry Pi boards.

mbedPi

This is an attempt to implement a limited number of mbed APIs for Raspberry Pi single-board computers. The project was inspired by and based on the arduPi library developed for the Arduino by Cooking Hacks .

/media/uploads/hudakz/board01.jpg

Specifications

  • Chip: Broadcom BCM2836 SoC
  • Core architecture: Quad-core ARM Cortex-A7
  • CPU frequency: 900 MHz
  • GPU: Dual Core VideoCore IV® Multimedia Co-Processor
  • Memory: 1GB LPDDR2
  • Operating System: Boots from Micro SD card, running a version of the Linux operating system
  • Power: Micro USB socket 5V, 2A

Connectors

  • Ethernet: 10/100 BaseT Ethernet socket
  • Video Output: HDMI (rev 1.3 & 1.4)
  • Audio Output: 3.5mm jack, HDMI
  • USB: 4 x USB 2.0 Connector
  • GPIO Connector: 40-pin 2.54 mm (100 mil) expansion header: 2x20 strip providing 27 GPIO pins as well as +3.3 V, +5 V and GND supply lines
  • Camera Connector: 15-pin MIPI Camera Serial Interface (CSI-2)
  • JTAG: Not populated
  • Display Connector: Display Serial Interface (DSI) 15 way flat flex cable connector with two data lanes and a clock lane
  • Memory Card Slot: Micro SDIO

GPIO connector pinout

Zoom in /media/uploads/hudakz/mbedpi_pinout02.png

Information

Only the labels printed in blue/white or green/white (i.e. p3, gpio2 ...) must be used in your code. The other labels are given as information (alternate-functions, power pins, ...).


Building programs for the Raspberry Pi with mbedPi

I use Qt Creator for development, however you can use any other IDE available on the Raspberry Pi (e.g. Geany) if you like. For a quick try:

  • Install Qt and the Qt Creator onto your Raspberry Pi. Then create a new "Blinky" Plain non-Qt C++ Project as follows: /media/uploads/hudakz/newproject.png

  • Change the main code as below:

main.cpp

#include "mbedPi.h"

int main()
{
    DigitalOut  myled(p7);

    while(1) {
        myled = 1; // LED is ON
        wait(0.2); // 200 ms
        myled = 0; // LED is OFF
        wait(1.0); // 1 sec
        printf("Blink\r\n");
    }
}


  • Copy the mbedPi.zip file into your project's folder and unzip.
  • Add the mbedPi.h and mbedPi.cpp files to your project by right clicking on the "Blinky" project and then clicking on the "Add Existing Files..." option in the local menu:

    /media/uploads/hudakz/addfiles.png

    /media/uploads/hudakz/addfiles02.png

  • Double click on Blinky.pro to open it for editing and add new libraries by inserting a new line as follows:

    /media/uploads/hudakz/libs.png

  • Compile the project.

  • Connect an LED through a 1k resistor to pin 7 and the ground on the Raspberry Pi GPIO connector.

  • Run the binary as sudo (sudo ./Blinky) and you should see the LED blinking. /media/uploads/hudakz/mbedpi_run.png

  • Press Ctrl+c to stop running the application.
Committer:
hudakz
Date:
Tue Dec 20 12:08:07 2022 +0000
Revision:
1:1f2d9982fa8c
mbed API for Raspberry Pi boards equipped with BCM2836 SoC.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
hudakz 1:1f2d9982fa8c 1 #include "mbed.h"
hudakz 1:1f2d9982fa8c 2
hudakz 1:1f2d9982fa8c 3 uint64_t timeElapsed;
hudakz 1:1f2d9982fa8c 4 int i = 0;
hudakz 1:1f2d9982fa8c 5 Timer timer;
hudakz 1:1f2d9982fa8c 6
hudakz 1:1f2d9982fa8c 7 /**
hudakz 1:1f2d9982fa8c 8 * @brief
hudakz 1:1f2d9982fa8c 9 * @note None
hudakz 1:1f2d9982fa8c 10 * @param None
hudakz 1:1f2d9982fa8c 11 * @retval None
hudakz 1:1f2d9982fa8c 12 */
hudakz 1:1f2d9982fa8c 13 int main()
hudakz 1:1f2d9982fa8c 14 {
hudakz 1:1f2d9982fa8c 15 DigitalOut led(gpio18);
hudakz 1:1f2d9982fa8c 16
hudakz 1:1f2d9982fa8c 17 timer.reset();
hudakz 1:1f2d9982fa8c 18 timer.start();
hudakz 1:1f2d9982fa8c 19
hudakz 1:1f2d9982fa8c 20 while (1) {
hudakz 1:1f2d9982fa8c 21 //ThisThread::sleep_for(500);
hudakz 1:1f2d9982fa8c 22 while (1) {
hudakz 1:1f2d9982fa8c 23 timeElapsed = timer.read_ms();
hudakz 1:1f2d9982fa8c 24 if (timeElapsed > 500) {
hudakz 1:1f2d9982fa8c 25 timer.reset();
hudakz 1:1f2d9982fa8c 26 break;
hudakz 1:1f2d9982fa8c 27 }
hudakz 1:1f2d9982fa8c 28 }
hudakz 1:1f2d9982fa8c 29
hudakz 1:1f2d9982fa8c 30 led = !led;
hudakz 1:1f2d9982fa8c 31 }
hudakz 1:1f2d9982fa8c 32 }
hudakz 1:1f2d9982fa8c 33