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 12:16:18 2022 +0000
Revision:
2:131555dc6fb7
Parent:
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 /*
hudakz 1:1f2d9982fa8c 2 * Copyright (C) 2016 Zoltan Hudak
hudakz 1:1f2d9982fa8c 3 * hudakz@outlook.com
hudakz 1:1f2d9982fa8c 4 *
hudakz 1:1f2d9982fa8c 5 * Parts Copyright (C) Libelium Comunicaciones Distribuidas S.L.
hudakz 1:1f2d9982fa8c 6 * http://www.libelium.com
hudakz 1:1f2d9982fa8c 7 *
hudakz 1:1f2d9982fa8c 8 * This program is free software: you can redistribute it and/or modify
hudakz 1:1f2d9982fa8c 9 * it under the terms of the GNU General Public License as published by
hudakz 1:1f2d9982fa8c 10 * the Free Software Foundation, either version 3 of the License, or
hudakz 1:1f2d9982fa8c 11 * (at your option) any later version.
hudakz 1:1f2d9982fa8c 12 *
hudakz 1:1f2d9982fa8c 13 * This program is distributed in the hope that it will be useful,
hudakz 1:1f2d9982fa8c 14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
hudakz 1:1f2d9982fa8c 15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
hudakz 1:1f2d9982fa8c 16 * GNU General Public License for more details.
hudakz 1:1f2d9982fa8c 17 *
hudakz 1:1f2d9982fa8c 18 * You should have received a copy of the GNU General Public License
hudakz 1:1f2d9982fa8c 19 * along with this program. If not, see <http://www.gnu.org/licenses/>.
hudakz 1:1f2d9982fa8c 20 *
hudakz 1:1f2d9982fa8c 21 * Version 1.0
hudakz 1:1f2d9982fa8c 22 */
hudakz 1:1f2d9982fa8c 23 #include "Thread.h"
hudakz 1:1f2d9982fa8c 24 /*$off*/
hudakz 1:1f2d9982fa8c 25
hudakz 1:1f2d9982fa8c 26 pthread_t idThread2;
hudakz 1:1f2d9982fa8c 27 pthread_t idThread3;
hudakz 1:1f2d9982fa8c 28 pthread_t idThread4;
hudakz 1:1f2d9982fa8c 29 pthread_t idThread5;
hudakz 1:1f2d9982fa8c 30 pthread_t idThread6;
hudakz 1:1f2d9982fa8c 31 pthread_t idThread7;
hudakz 1:1f2d9982fa8c 32 pthread_t idThread8;
hudakz 1:1f2d9982fa8c 33 pthread_t idThread9;
hudakz 1:1f2d9982fa8c 34 pthread_t idThread10;
hudakz 1:1f2d9982fa8c 35 pthread_t idThread11;
hudakz 1:1f2d9982fa8c 36 pthread_t idThread12;
hudakz 1:1f2d9982fa8c 37 pthread_t idThread13;
hudakz 1:1f2d9982fa8c 38 pthread_t idThread14;
hudakz 1:1f2d9982fa8c 39 pthread_t idThread15;
hudakz 1:1f2d9982fa8c 40 pthread_t idThread16;
hudakz 1:1f2d9982fa8c 41 pthread_t idThread17;
hudakz 1:1f2d9982fa8c 42 pthread_t idThread18;
hudakz 1:1f2d9982fa8c 43 pthread_t idThread19;
hudakz 1:1f2d9982fa8c 44 pthread_t idThread20;
hudakz 1:1f2d9982fa8c 45 pthread_t idThread21;
hudakz 1:1f2d9982fa8c 46 pthread_t idThread22;
hudakz 1:1f2d9982fa8c 47 pthread_t idThread23;
hudakz 1:1f2d9982fa8c 48 pthread_t idThread24;
hudakz 1:1f2d9982fa8c 49 pthread_t idThread25;
hudakz 1:1f2d9982fa8c 50 pthread_t idThread26;
hudakz 1:1f2d9982fa8c 51 pthread_t idThread27;
hudakz 1:1f2d9982fa8c 52
hudakz 1:1f2d9982fa8c 53 pthread_t* idThreads[26] =
hudakz 1:1f2d9982fa8c 54 {
hudakz 1:1f2d9982fa8c 55 &idThread2,
hudakz 1:1f2d9982fa8c 56 &idThread3,
hudakz 1:1f2d9982fa8c 57 &idThread4,
hudakz 1:1f2d9982fa8c 58 &idThread5,
hudakz 1:1f2d9982fa8c 59 &idThread6,
hudakz 1:1f2d9982fa8c 60 &idThread7,
hudakz 1:1f2d9982fa8c 61 &idThread8,
hudakz 1:1f2d9982fa8c 62 &idThread9,
hudakz 1:1f2d9982fa8c 63 &idThread10,
hudakz 1:1f2d9982fa8c 64 &idThread11,
hudakz 1:1f2d9982fa8c 65 &idThread12,
hudakz 1:1f2d9982fa8c 66 &idThread13,
hudakz 1:1f2d9982fa8c 67 &idThread14,
hudakz 1:1f2d9982fa8c 68 &idThread15,
hudakz 1:1f2d9982fa8c 69 &idThread16,
hudakz 1:1f2d9982fa8c 70 &idThread17,
hudakz 1:1f2d9982fa8c 71 &idThread18,
hudakz 1:1f2d9982fa8c 72 &idThread19,
hudakz 1:1f2d9982fa8c 73 &idThread20,
hudakz 1:1f2d9982fa8c 74 &idThread21,
hudakz 1:1f2d9982fa8c 75 &idThread22,
hudakz 1:1f2d9982fa8c 76 &idThread23,
hudakz 1:1f2d9982fa8c 77 &idThread24,
hudakz 1:1f2d9982fa8c 78 &idThread25,
hudakz 1:1f2d9982fa8c 79 &idThread26,
hudakz 1:1f2d9982fa8c 80 &idThread27
hudakz 1:1f2d9982fa8c 81 };
hudakz 1:1f2d9982fa8c 82
hudakz 1:1f2d9982fa8c 83 /*$on*/
hudakz 1:1f2d9982fa8c 84
hudakz 1:1f2d9982fa8c 85 /* This is the function that will be running in a thread if
hudakz 1:1f2d9982fa8c 86 * attachInterrupt() is called */
hudakz 1:1f2d9982fa8c 87 void* threadFunction(void* args)
hudakz 1:1f2d9982fa8c 88 {
hudakz 1:1f2d9982fa8c 89 ThreadArg* arguments = (ThreadArg*)args;
hudakz 1:1f2d9982fa8c 90 int pin = arguments->pin;
hudakz 1:1f2d9982fa8c 91
hudakz 1:1f2d9982fa8c 92 int GPIO_FN_MAXLEN = 32;
hudakz 1:1f2d9982fa8c 93 int RDBUF_LEN = 5;
hudakz 1:1f2d9982fa8c 94
hudakz 1:1f2d9982fa8c 95 char fn[GPIO_FN_MAXLEN];
hudakz 1:1f2d9982fa8c 96 int fd, ret;
hudakz 1:1f2d9982fa8c 97 struct pollfd pfd;
hudakz 1:1f2d9982fa8c 98 char rdbuf[RDBUF_LEN];
hudakz 1:1f2d9982fa8c 99
hudakz 1:1f2d9982fa8c 100 memset(rdbuf, 0x00, RDBUF_LEN);
hudakz 1:1f2d9982fa8c 101 memset(fn, 0x00, GPIO_FN_MAXLEN);
hudakz 1:1f2d9982fa8c 102
hudakz 1:1f2d9982fa8c 103 snprintf(fn, GPIO_FN_MAXLEN - 1, "/sys/class/gpio/gpio%d/value", pin);
hudakz 1:1f2d9982fa8c 104 fd = open(fn, O_RDONLY);
hudakz 1:1f2d9982fa8c 105 if (fd < 0) {
hudakz 1:1f2d9982fa8c 106 perror(fn);
hudakz 1:1f2d9982fa8c 107 exit(1);
hudakz 1:1f2d9982fa8c 108 }
hudakz 1:1f2d9982fa8c 109
hudakz 1:1f2d9982fa8c 110 pfd.fd = fd;
hudakz 1:1f2d9982fa8c 111 pfd.events = POLLPRI;
hudakz 1:1f2d9982fa8c 112
hudakz 1:1f2d9982fa8c 113 ret = unistd::read(fd, rdbuf, RDBUF_LEN - 1);
hudakz 1:1f2d9982fa8c 114 if (ret < 0) {
hudakz 1:1f2d9982fa8c 115 perror("Error reading interrupt file\n");
hudakz 1:1f2d9982fa8c 116 exit(1);
hudakz 1:1f2d9982fa8c 117 }
hudakz 1:1f2d9982fa8c 118
hudakz 1:1f2d9982fa8c 119 while (1) {
hudakz 1:1f2d9982fa8c 120 memset(rdbuf, 0x00, RDBUF_LEN);
hudakz 1:1f2d9982fa8c 121 unistd::lseek(fd, 0, SEEK_SET);
hudakz 1:1f2d9982fa8c 122 ret = poll(&pfd, 1, -1);
hudakz 1:1f2d9982fa8c 123 if (ret < 0) {
hudakz 1:1f2d9982fa8c 124 perror("Error waiting for interrupt\n");
hudakz 1:1f2d9982fa8c 125 unistd::close(fd);
hudakz 1:1f2d9982fa8c 126 exit(1);
hudakz 1:1f2d9982fa8c 127 }
hudakz 1:1f2d9982fa8c 128
hudakz 1:1f2d9982fa8c 129 if (ret == 0) {
hudakz 1:1f2d9982fa8c 130 printf("Timeout\n");
hudakz 1:1f2d9982fa8c 131 continue;
hudakz 1:1f2d9982fa8c 132 }
hudakz 1:1f2d9982fa8c 133
hudakz 1:1f2d9982fa8c 134 ret = unistd::read(fd, rdbuf, RDBUF_LEN - 1);
hudakz 1:1f2d9982fa8c 135 if (ret < 0) {
hudakz 1:1f2d9982fa8c 136 perror("Error reading interrupt file\n");
hudakz 1:1f2d9982fa8c 137 exit(1);
hudakz 1:1f2d9982fa8c 138 }
hudakz 1:1f2d9982fa8c 139
hudakz 1:1f2d9982fa8c 140 //Interrupt. We call user function.
hudakz 1:1f2d9982fa8c 141 arguments->func();
hudakz 1:1f2d9982fa8c 142 }
hudakz 1:1f2d9982fa8c 143 }
hudakz 1:1f2d9982fa8c 144
hudakz 1:1f2d9982fa8c 145 /**
hudakz 1:1f2d9982fa8c 146 * @brief
hudakz 1:1f2d9982fa8c 147 * @note
hudakz 1:1f2d9982fa8c 148 * @param
hudakz 1:1f2d9982fa8c 149 * @retval
hudakz 1:1f2d9982fa8c 150 */
hudakz 1:1f2d9982fa8c 151 pthread_t* getThreadIdFromPin(int pin)
hudakz 1:1f2d9982fa8c 152 {
hudakz 1:1f2d9982fa8c 153 int i = pin - 2;
hudakz 1:1f2d9982fa8c 154 if ((0 <= i) && (i <= 25))
hudakz 1:1f2d9982fa8c 155 return idThreads[i];
hudakz 1:1f2d9982fa8c 156 else return NULL;
hudakz 1:1f2d9982fa8c 157 }