Zoltan Hudak / mbedPi

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 .

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

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:
  
  
• Change the main code as below:

#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:
  
  
  
  
  
  
• Double click on Blinky.pro to open it for editing and add new libraries by inserting a new line as follows:
  
  
  
  
• 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.
  
  
• Press Ctrl+c to stop running the application.

diff -r 91392e1f8551 -r 1f2d9982fa8c include/I2C.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/include/I2C.h	Tue Dec 20 12:08:07 2022 +0000
@@ -0,0 +1,32 @@
+#ifndef _I2C_H_
+#define _I2C_H_
+
+#include "BCM2835.h"
+
+class   I2C
+{
+public:
+    I2C();
+    ~I2C();
+    uint8_t read(uint8_t address, char* buf, int len, bool repeat = false);
+    uint8_t read(bool ack = true);
+    int     write(uint8_t address, const char* buf, int len, bool repeat = false);
+    int     write(uint8_t data);
+private:
+    int     _memfd;
+    int     _i2c_byte_wait_us;
+    int     _i2c_bytes_to_read;
+    uint8_t _addr;
+
+    void    setAddress(uint8_t address);
+    void    requestFrom(unsigned char address, int len);
+    uint8_t read(char* buf);
+    uint8_t read_repeat(char* buf, int len);
+    int     write(const char* buf, int len);
+    int     map_peripheral(struct bcm2835_peripheral* p);
+    void    unmap_peripheral(struct bcm2835_peripheral* p);
+    void    wait_i2c_done();
+};
+
+#endif	// _I2C_H_
+