树莓派利用MCP2515基于BCM2835完成SPI转CAN（C语言实现）

/* bcm2835.c // C and C++ support for Broadcom BCM 2835 as used in Raspberry Pi // http://elinux.org/RPi_Low-level_peripherals // http://www.raspberrypi.org/wp-content/uploads/2012/02/BCM2835-ARM-Peripherals.pdf // // Author: Mike McCauley // Copyright (C) 2011-2013 Mike McCauley // $Id: bcm2835.c,v 1.25 2018/01/16 21:55:07 mikem Exp mikem $ */ #include <stdlib.h> #include <stdio.h> #include <errno.h> #include <fcntl.h> #include <sys/mman.h> #include <string.h> #include <time.h> #include <unistd.h> #include <sys/types.h> #define BCK2835_LIBRARY_BUILD #include "bcm2835.h" /* This define enables a little test program (by default a blinking output on pin RPI_GPIO_PIN_11) // You can do some safe, non-destructive testing on any platform with: // gcc bcm2835.c -D BCM2835_TEST // ./a.out */ /*#define BCM2835_TEST*/ /* Uncommenting this define compiles alternative I2C code for the version 1 RPi // The P1 header I2C pins are connected to SDA0 and SCL0 on V1. // By default I2C code is generated for the V2 RPi which has SDA1 and SCL1 connected. */ /* #define I2C_V1*/ /* Physical address and size of the peripherals block // May be overridden on RPi2 */ uint32_t *bcm2835_peripherals_base = (uint32_t *)BCM2835_PERI_BASE; uint32_t bcm2835_peripherals_size = BCM2835_PERI_SIZE; /* Virtual memory address of the mapped peripherals block */ uint32_t *bcm2835_peripherals = (uint32_t *)MAP_FAILED; /* And the register bases within the peripherals block */ volatile uint32_t *bcm2835_gpio = (uint32_t *)MAP_FAILED; volatile uint32_t *bcm2835_pwm = (uint32_t *)MAP_FAILED; volatile uint32_t *bcm2835_clk = (uint32_t *)MAP_FAILED; volatile uint32_t *bcm2835_pads = (uint32_t *)MAP_FAILED; volatile uint32_t *bcm2835_spi0 = (uint32_t *)MAP_FAILED; volatile uint32_t *bcm2835_bsc0 = (uint32_t *)MAP_FAILED; volatile uint32_t *bcm2835_bsc1 = (uint32_t *)MAP_FAILED; volatile uint32_t *bcm2835_st = (uint32_t *)MAP_FAILED; volatile uint32_t *bcm2835_aux = (uint32_t *)MAP_FAILED; volatile uint32_t *bcm2835_spi1 = (uint32_t *)MAP_FAILED; /* This variable allows us to test on hardware other than RPi. // It prevents access to the kernel memory, and does not do any peripheral access // Instead it prints out what it _would_ do if debug were 0 */ static uint8_t debug = 0; /* I2C The time needed to transmit one byte. In microseconds. */ static int i2c_byte_wait_us = 0; /* SPI bit order. BCM2835 SPI0 only supports MSBFIRST, so we instead * have a software based bit reversal, based on a contribution by Damiano Benedetti */ static uint8_t bcm2835_spi_bit_order = BCM2835_SPI_BIT_ORDER_MSBFIRST; static uint8_t bcm2835_byte_reverse_table[] = { 0x00, 0x80, 0x40, 0xc0, 0x20, 0xa0, 0x60, 0xe0, 0x10, 0x90, 0x50, 0xd0, 0x30, 0xb0, 0x70, 0xf0, 0x08, 0x88, 0x48, 0xc8, 0x28, 0xa8, 0x68, 0xe8, 0x18, 0x98, 0x58, 0xd8, 0x38, 0xb8, 0x78, 0xf8, 0x04, 0x84, 0x44, 0xc4, 0x24, 0xa4, 0x64, 0xe4, 0x14, 0x94, 0x54, 0xd4, 0x34, 0xb4, 0x74, 0xf4, 0x0c, 0x8c, 0x4c, 0xcc, 0x2c, 0xac, 0x6c, 0xec, 0x1c, 0x9c, 0x5c, 0xdc, 0x3c, 0xbc, 0x7c, 0xfc, 0x02, 0x82, 0x42, 0xc2, 0x22, 0xa2, 0x62, 0xe2, 0x12, 0x92, 0x52, 0xd2, 0x32, 0xb2, 0x72, 0xf2, 0x0a, 0x8a, 0x4a, 0xca, 0x2a, 0xaa, 0x6a, 0xea, 0x1a, 0x9a, 0x5a, 0xda, 0x3a, 0xba, 0x7a, 0xfa, 0x06, 0x86, 0x46, 0xc6, 0x26, 0xa6, 0x66, 0xe6, 0x16, 0x96, 0x56, 0xd6, 0x36, 0xb6, 0x76, 0xf6, 0x0e, 0x8e, 0x4e, 0xce, 0x2e, 0xae, 0x6e, 0xee, 0x1e, 0x9e, 0x5e, 0xde, 0x3e, 0xbe, 0x7e, 0xfe, 0x01, 0x81, 0x41, 0xc1, 0x21, 0xa1, 0x61, 0xe1, 0x11, 0x91, 0x51, 0xd1, 0x31, 0xb1, 0x71, 0xf1, 0x09, 0x89, 0x49, 0xc9, 0x29, 0xa9, 0x69, 0xe9, 0x19, 0x99, 0x59, 0xd9, 0x39, 0xb9, 0x79, 0xf9, 0x05, 0x85, 0x45, 0xc5, 0x25, 0xa5, 0x65, 0xe5, 0x15, 0x95, 0x55, 0xd5, 0x35, 0xb5, 0x75, 0xf5, 0x0d, 0x8d, 0x4d, 0xcd, 0x2d, 0xad, 0x6d, 0xed, 0x1d, 0x9d, 0x5d, 0xdd, 0x3d, 0xbd, 0x7d, 0xfd, 0x03, 0x83, 0x43, 0xc3, 0x23, 0xa3, 0x63, 0xe3, 0x13, 0x93, 0x53, 0xd3, 0x33, 0xb3, 0x73, 0xf3, 0x0b, 0x8b, 0x4b, 0xcb, 0x2b, 0xab, 0x6b, 0xeb, 0x1b, 0x9b, 0x5b, 0xdb, 0x3b, 0xbb, 0x7b, 0xfb, 0x07, 0x87, 0x47, 0xc7, 0x27, 0xa7, 0x67, 0xe7, 0x17, 0x97, 0x57, 0xd7, 0x37, 0xb7, 0x77, 0xf7, 0x0f, 0x8f, 0x4f, 0xcf, 0x2f, 0xaf, 0x6f, 0xef, 0x1f, 0x9f, 0x5f, 0xdf, 0x3f, 0xbf, 0x7f, 0xff }; static uint8_t bcm2835_correct_order(uint8_t b) { if (bcm2835_spi_bit_order == BCM2835_SPI_BIT_ORDER_LSBFIRST) return bcm2835_byte_reverse_table[b]; else return b; } /* // Low level register access functions */ /* Function to return the pointers to the hardware register bases */ uint32_t* bcm2835_regbase(uint8_t regbase) { switch (regbase) { case BCM2835_REGBASE_ST: return (uint32_t *)bcm2835_st; case BCM2835_REGBASE_GPIO: return (uint32_t *)bcm2835_gpio; case BCM2835_REGBASE_PWM: return (uint32_t *)bcm2835_pwm; case BCM2835_REGBASE_CLK: return (uint32_t *)bcm2835_clk; case BCM2835_REGBASE_PADS: return (uint32_t *)bcm2835_pads; case BCM2835_REGBASE_SPI0: return (uint32_t *)bcm2835_spi0; case BCM2835_REGBASE_BSC0: return (uint32_t *)bcm2835_bsc0; case BCM2835_REGBASE_BSC1: return (uint32_t *)bcm2835_st; case BCM2835_REGBASE_AUX: return (uint32_t *)bcm2835_aux; case BCM2835_REGBASE_SPI1: return (uint32_t *)bcm2835_spi1; } return (uint32_t *)MAP_FAILED; } void bcm2835_set_debug(uint8_t d) { debug = d; } unsigned int bcm2835_version(void) { return BCM2835_VERSION; } /* Read with memory barriers from peripheral * */ uint32_t bcm2835_peri_read(volatile uint32_t* paddr) { uint32_t ret; if (debug) { printf("bcm2835_peri_read paddr %p\n", (void *) paddr); return 0; } else { __sync_synchronize(); ret = *paddr; __sync_synchronize(); return ret; } } /* read from peripheral without the read barrier * This can only be used if more reads to THE SAME peripheral * will follow. The sequence must terminate with memory barrier * before any read or write to another peripheral can occur. * The MB can be explicit, or one of the barrier read/write calls. */ uint32_t bcm2835_peri_read_nb(volatile uint32_t* paddr) { if (debug) { printf("bcm2835_peri_read_nb paddr %p\n", paddr); return 0; } else { return *paddr; } } /* Write with memory barriers to peripheral */ void bcm2835_peri_write(volatile uint32_t* paddr, uint32_t value) { if (debug) { printf("bcm2835_peri_write paddr %p, value %08X\n", paddr, value); } else { __sync_synchronize(); *paddr = value; __sync_synchronize(); } } /* write to peripheral without the write barrier */ void bcm2835_peri_write_nb(volatile uint32_t* paddr, uint32_t value) { if (debug) { printf("bcm2835_peri_write_nb paddr %p, value %08X\n", paddr, value); } else { *paddr = value; } } /* Set/clear only the bits in value covered by the mask * This is not atomic - can be interrupted. */ 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); } /* // Low level convenience functions */ /* Function select // pin is a BCM2835 GPIO pin number NOT RPi pin number // There are 6 control registers, each control the functions of a block // of 10 pins. // Each control register has 10 sets of 3 bits per GPIO pin: // // 000 = GPIO Pin X is an input // 001 = GPIO Pin X is an output // 100 = GPIO Pin X takes alternate function 0 // 101 = GPIO Pin X takes alternate function 1 // 110 = GPIO Pin X takes alternate function 2 // 111 = GPIO Pin X takes alternate function 3 // 011 = GPIO Pin X takes alternate function 4 // 010 = GPIO Pin X takes alternate function 5 // //