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
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:
- 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:
- 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.
source/Peripheral.cpp
- Committer:
- hudakz
- Date:
- 21 months ago
- Revision:
- 1:1f2d9982fa8c
File content as of revision 1:1f2d9982fa8c:
//#include "mbed.h" #include "BCM2835.h" #include "Thread.h" #include "ThisThread.h" #include "Peripheral.h" struct bcm2835_peripheral bsc_rev1 = { BCM2835_PERI_BASE + 0X205000, 0, 0, 0 }; struct bcm2835_peripheral bsc_rev2 = { BCM2835_PERI_BASE + 0X804000, 0, 0, 0 }; struct bcm2835_peripheral bsc0; struct bcm2835_peripheral gpio = { BCM2835_PERI_BASE + 0x200000, 0, 0, 0 }; timeval start_program, end_point; off_t bcm2835_peripherals_base = BCM2835_PERI_BASE; size_t bcm2835_peripherals_size = BCM2835_PERI_SIZE; volatile uint32_t* bcm2835_peripherals; volatile uint32_t* bcm2835_pwm = (uint32_t *)MAP_FAILED; volatile uint32_t* bcm2835_clk = (uint32_t *)MAP_FAILED; volatile uint32_t* bcm2835_bsc1 = (uint32_t *)MAP_FAILED; volatile uint32_t* bcm2835_spi0 = (uint32_t *)MAP_FAILED; volatile uint32_t* bcm2835_st = (uint32_t *)MAP_FAILED; //Constructor Peripheral::Peripheral() { REV = getBoardRev(); if (map_peripheral(&gpio) == -1) { printf("Failed to map the physical GPIO registers into the virtual memory space.\n"); } memfd = -1; // Open the master /dev/memory device if ((memfd = open("/dev/mem", O_RDWR | O_SYNC)) < 0) { fprintf(stderr, "bcm2835_init: Unable to open /dev/mem: %s\n", strerror(errno)); exit(1); } bcm2835_peripherals = mapmem("gpio", bcm2835_peripherals_size, memfd, bcm2835_peripherals_base); if (bcm2835_peripherals == MAP_FAILED) exit(1); /* Now compute the base addresses of various peripherals, // which are at fixed offsets within the mapped peripherals block // Caution: bcm2835_peripherals is uint32_t*, so divide offsets by 4 */ bcm2835_pwm = bcm2835_peripherals + BCM2835_GPIO_PWM/4; bcm2835_clk = bcm2835_peripherals + BCM2835_CLOCK_BASE/4; bcm2835_spi0 = bcm2835_peripherals + BCM2835_SPI0_BASE/4; bcm2835_bsc1 = bcm2835_peripherals + BCM2835_BSC1_BASE/4; /* I2C */ bcm2835_st = bcm2835_peripherals + BCM2835_ST_BASE/4; // start timer gettimeofday(&start_program, NULL); } //Destructor Peripheral::~Peripheral() { unmap_peripheral(&gpio); bcm2835_pwm = (uint32_t *)MAP_FAILED; bcm2835_clk = (uint32_t *)MAP_FAILED; bcm2835_spi0 = (uint32_t *)MAP_FAILED; bcm2835_bsc1 = (uint32_t *)MAP_FAILED; } /******************* * Private methods * *******************/ // Exposes the physical address defined in the passed structure using mmap on /dev/mem int Peripheral::map_peripheral(struct bcm2835_peripheral* p) { // Open /dev/mem if ((p->mem_fd = open("/dev/mem", O_RDWR | O_SYNC)) < 0) { printf("Failed to open /dev/mem, try checking permissions.\n"); return -1; } p->map = mmap ( NULL, BLOCK_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, p->mem_fd, // File descriptor to physical memory virtual file '/dev/mem' p->addr_p // Address in physical map that we want this memory block to expose ); if (p->map == MAP_FAILED) { perror("mmap"); return -1; } p->addr = (volatile unsigned int*)p->map; return 0; } /** * @brief * @note * @param * @retval */ void Peripheral::unmap_peripheral(struct bcm2835_peripheral* p) { munmap(p->map, BLOCK_SIZE); unistd::close(p->mem_fd); } // // Low level convenience functions // /** * @brief * @note * @param * @retval */ uint32_t* mapmem(const char* msg, size_t size, int fd, off_t off) { uint32_t* map = (uint32_t*)mmap(NULL, size, (PROT_READ | PROT_WRITE), MAP_SHARED, fd, off); if (MAP_FAILED == map) fprintf(stderr, "bcm2835_init: %s mmap failed: %s\n", msg, strerror(errno)); return map; } // safe read from peripheral uint32_t bcm2835_peri_read(volatile uint32_t* paddr) { uint32_t ret = *paddr; ret = *paddr; return ret; } // read from peripheral without the read barrier uint32_t bcm2835_peri_read_nb(volatile uint32_t* paddr) { return *paddr; } // safe write to peripheral void bcm2835_peri_write(volatile uint32_t* paddr, uint32_t value) { *paddr = value; *paddr = value; } // write to peripheral without the write barrier void bcm2835_peri_write_nb(volatile uint32_t* paddr, uint32_t value) { *paddr = value; } // Set/clear only the bits in value covered by the mask void bcm2835_peri_set_bits(volatile uint32_t* paddr, uint32_t value, uint32_t mask) { uint32_t v = bcm2835_peri_read(paddr); v = (v &~mask) | (value & mask); bcm2835_peri_write(paddr, v); } /** * @brief * @note * @param * @retval */ int getBoardRev() { FILE* cpu_info; char line[120]; char* c, finalChar; //static int rev = 0; if (REV != 0) return REV; if ((cpu_info = fopen("/proc/cpuinfo", "r")) == NULL) { fprintf(stderr, "Unable to open /proc/cpuinfo. Cannot determine board reivision.\n"); exit(1); } while (fgets(line, 120, cpu_info) != NULL) { if (strncmp(line, "Revision", 8) == 0) break; } fclose(cpu_info); if (line == NULL) { fprintf(stderr, "Unable to determine board revision from /proc/cpuinfo.\n"); exit(1); } for (c = line; *c; ++c) if (isdigit(*c)) break; if (!isdigit(*c)) { fprintf(stderr, "Unable to determine board revision from /proc/cpuinfo\n"); fprintf(stderr, " (Info not found in: %s\n", line); exit(1); } finalChar = c[strlen(c) - 2]; if ((finalChar == '2') || (finalChar == '3')) { bsc0 = bsc_rev1; return 1; } else { bsc0 = bsc_rev2; return 2; } } /** * @brief * @note * @param * @retval */ void attachInterrupt(PinName p, void (*f) (), Digivalue m) { int GPIOPin = p; pthread_t* threadId = getThreadIdFromPin(p); struct ThreadArg* threadArgs = (ThreadArg*)malloc(sizeof(ThreadArg)); threadArgs->func = f; threadArgs->pin = GPIOPin; //Export pin for interrupt FILE* fp = fopen("/sys/class/gpio/export", "w"); if (fp == NULL) { fprintf(stderr, "Unable to export pin %d for interrupt\n", p); exit(1); } else { fprintf(fp, "%d", GPIOPin); } fclose(fp); //The system to create the file /sys/class/gpio/gpio<GPIO number> //So we wait a bit ThisThread::sleep_for_ms(1); char* interruptFile = NULL; asprintf(&interruptFile, "/sys/class/gpio/gpio%d/edge", GPIOPin); //Set detection condition fp = fopen(interruptFile, "w"); if (fp == NULL) { fprintf(stderr, "Unable to set detection type on pin %d\n", p); exit(1); } else { switch (m) { case RISING: fprintf(fp, "rising"); break; case FALLING: fprintf(fp, "falling"); break; default: fprintf(fp, "both"); break; } } fclose(fp); if (*threadId == 0) { //Create a thread passing the pin and function pthread_create(threadId, NULL, threadFunction, (void*)threadArgs); } else { //First cancel the existing thread for that pin pthread_cancel(*threadId); //Create a thread passing the pin, function and mode pthread_create(threadId, NULL, threadFunction, (void*)threadArgs); } } /** * @brief * @note * @param * @retval */ void detachInterrupt(PinName p) { int GPIOPin = p; FILE* fp = fopen("/sys/class/gpio/unexport", "w"); if (fp == NULL) { fprintf(stderr, "Unable to unexport pin %d for interrupt\n", p); exit(1); } else { fprintf(fp, "%d", GPIOPin); } fclose(fp); pthread_t* threadId = getThreadIdFromPin(p); pthread_cancel(*threadId); } Peripheral peripheral = Peripheral();