openmv/src/omv/soft_i2c.c
2015-05-05 13:29:53 +03:00

181 lines
3.6 KiB
C

/*
* This file is part of the OpenMV project.
* Copyright (c) 2013/2014 Ibrahim Abdelkader <i.abdalkader@gmail.com>
* This work is licensed under the MIT license, see the file LICENSE for details.
*
* Software I2C implementation.
*
*/
#include <stdbool.h>
#include <stm32f4xx_hal.h>
#include "soft_i2c.h"
#include "mp.h"
#define I2C_PORT GPIOB
#define I2C_SIOC_PIN GPIO_PIN_10
#define I2C_SIOD_PIN GPIO_PIN_11
#define I2C_SIOC_H() HAL_GPIO_WritePin(I2C_PORT, I2C_SIOC_PIN, GPIO_PIN_SET)
#define I2C_SIOC_L() HAL_GPIO_WritePin(I2C_PORT, I2C_SIOC_PIN, GPIO_PIN_RESET)
#define I2C_SIOD_H() HAL_GPIO_WritePin(I2C_PORT, I2C_SIOD_PIN, GPIO_PIN_SET)
#define I2C_SIOD_L() HAL_GPIO_WritePin(I2C_PORT, I2C_SIOD_PIN, GPIO_PIN_RESET)
#define I2C_SIOD_READ() HAL_GPIO_ReadPin(I2C_PORT, I2C_SIOD_PIN)
#define I2C_SIOD_WRITE(bit) HAL_GPIO_WritePin(I2C_PORT, I2C_SIOD_PIN, bit);
#define ACK 0
#define NACK 1
static void delay(void)
{
volatile uint32_t i;
for (i=0; i<18; i++);
}
static void i2c_start(void)
{
/* The start of data transmission occurs when
SIO_D is driven low while SIO_C is high */
I2C_SIOC_H();
I2C_SIOD_H();
delay();
I2C_SIOD_L();
delay();
I2C_SIOC_L();
delay();
}
static void i2c_stop(void)
{
/* The stop of data transmission occurs when
SIO_D is driven high while SIO_C is high */
I2C_SIOC_L();
I2C_SIOD_L();
delay();
I2C_SIOC_H();
delay();
I2C_SIOD_H();
delay();
}
static uint8_t i2c_read_byte(char ack)
{
uint8_t data = 0;
for(char i = 0; i < 8; i++) {
I2C_SIOC_H();
delay();
data |= I2C_SIOD_READ()&0x01;
data <<= (i != 7);
I2C_SIOC_L();
if (i == 7) {
/* Write ACK */
I2C_SIOD_WRITE(ack);
}
delay();
}
I2C_SIOC_H();
delay();
I2C_SIOC_L();
I2C_SIOD_H();
delay();
return data;
}
static char i2c_write_byte(uint8_t data)
{
char i;
/* Shift the 8 bits out */
for (i=0; i<8; i++) {
if (data & 0x80) {
I2C_SIOD_H();
} else {
I2C_SIOD_L();
}
I2C_SIOC_H();
delay();
I2C_SIOC_L();
delay();
data <<= 1;
}
I2C_SIOC_H();
delay();
/* Read ACK */
i = I2C_SIOD_READ()&0x01;
I2C_SIOC_L();
delay();
I2C_SIOD_H();
return i;
}
int soft_i2c_read_bytes(uint8_t slv_addr, uint8_t *buf, int len, bool stop)
{
int ret = 0;
mp_uint_t atomic_state = MICROPY_BEGIN_ATOMIC_SECTION();
i2c_start();
ret |= i2c_write_byte(slv_addr | 0x01);
for (int i=0; i<len; i++) {
buf[i] = i2c_read_byte(ACK);
}
if (stop) {
i2c_stop();
}
MICROPY_END_ATOMIC_SECTION(atomic_state);
return ret;
}
int soft_i2c_write_bytes(uint8_t slv_addr, uint8_t *buf, int len, bool stop)
{
uint8_t ret = 0;
mp_uint_t atomic_state = MICROPY_BEGIN_ATOMIC_SECTION();
i2c_start();
ret |= i2c_write_byte(slv_addr);
for (int i=0; i<len; i++) {
ret |= i2c_write_byte(*buf++);
}
if (stop) {
i2c_stop();
}
MICROPY_END_ATOMIC_SECTION(atomic_state);
return ret;
}
void soft_i2c_init()
{
/* Conigure I2C GPIOs */
GPIO_InitTypeDef GPIO_InitStructure;
GPIO_InitStructure.Pull = GPIO_NOPULL;
GPIO_InitStructure.Speed = GPIO_SPEED_MEDIUM;
GPIO_InitStructure.Mode = GPIO_MODE_OUTPUT_OD;
GPIO_InitStructure.Pin = I2C_SIOC_PIN;
HAL_GPIO_Init(I2C_PORT, &GPIO_InitStructure);
GPIO_InitStructure.Pin = I2C_SIOD_PIN;
HAL_GPIO_Init(I2C_PORT, &GPIO_InitStructure);
I2C_SIOC_H();
I2C_SIOD_H();
delay();
}