#include "soft_i2c.h"
#ifndef __NOP
#define __NOP() __asm volatile ("nop")
#endif
static soft_i2c_status_t soft_i2c_prepare_bus(soft_i2c_bus_t *bus);
static void soft_i2c_delay(const soft_i2c_bus_t *bus);
static soft_i2c_status_t soft_i2c_drive_scl(soft_i2c_bus_t *bus, soft_i2c_pin_state_t state);
static soft_i2c_status_t soft_i2c_drive_sda(soft_i2c_bus_t *bus, soft_i2c_pin_state_t state);
static soft_i2c_status_t soft_i2c_start(soft_i2c_bus_t *bus);
static soft_i2c_status_t soft_i2c_repeated_start(soft_i2c_bus_t *bus);
static void soft_i2c_stop(soft_i2c_bus_t *bus);
static soft_i2c_status_t soft_i2c_write_byte(soft_i2c_bus_t *bus, uint8_t value);
static soft_i2c_status_t soft_i2c_read_byte(soft_i2c_bus_t *bus, uint8_t *value, int last_byte);
/* 初始化软I2C总线：确认GPIO操作回调存在并设置默认延时 */
soft_i2c_status_t soft_i2c_bus_init(soft_i2c_bus_t *bus)
{
if ((bus == NULL) ||
(bus->scl.write == NULL) || (bus->scl.read == NULL) ||
(bus->sda.write == NULL) || (bus->sda.read == NULL)) {
return SOFT_I2C_STATUS_INVALID_PARAM;
}
if (bus->delay_ticks == 0U) {
bus->delay_ticks = SOFT_I2C_DEFAULT_DELAY_TICKS;
}
if (bus->stretch_timeout_ticks == 0U) {
bus->stretch_timeout_ticks = SOFT_I2C_DEFAULT_STRETCH_TICKS;
}
soft_i2c_drive_scl(bus, SOFT_I2C_PIN_SET);
soft_i2c_drive_sda(bus, SOFT_I2C_PIN_SET);
bus->initialized = 1U;
return SOFT_I2C_STATUS_OK;
}
/* 执行起始+地址+数据的写入流程，遇到NACK立即停止 */
soft_i2c_status_t soft_i2c_master_transmit(soft_i2c_bus_t *bus, uint8_t address,
const uint8_t *data, size_t size)
{
if ((data == NULL) && (size > 0U)) {
return SOFT_I2C_STATUS_INVALID_PARAM;
}
soft_i2c_status_t status = soft_i2c_prepare_bus(bus);
if (status != SOFT_I2C_STATUS_OK) {
return status;
}
int started = 0;
status = soft_i2c_start(bus);
if (status != SOFT_I2C_STATUS_OK) {
goto done;
}
started = 1;
status = soft_i2c_write_byte(bus, address & (uint8_t)~0x01U);
if (status != SOFT_I2C_STATUS_OK) {
goto done;
}
for (size_t i = 0; i < size; ++i) {
status = soft_i2c_write_byte(bus, data[i]);
if (status != SOFT_I2C_STATUS_OK) {
goto done;
}
}
done:
if (started) {
soft_i2c_stop(bus);
}
return status;
}
/* 仅执行读流程，负责发送最后一个NACK并停止 */
soft_i2c_status_t soft_i2c_master_receive(soft_i2c_bus_t *bus, uint8_t address,
uint8_t *data, size_t size)
{
if ((data == NULL) && (size > 0U)) {
return SOFT_I2C_STATUS_INVALID_PARAM;
}
if (size == 0U) {
return SOFT_I2C_STATUS_OK;
}
soft_i2c_status_t status = soft_i2c_prepare_bus(bus);
if (status != SOFT_I2C_STATUS_OK) {
return status;
}
int started = 0;
status = soft_i2c_start(bus);
if (status != SOFT_I2C_STATUS_OK) {
goto done;
}
started = 1;
status = soft_i2c_write_byte(bus, address | 0x01U);
if (status != SOFT_I2C_STATUS_OK) {
goto done;
}
for (size_t i = 0; i < size; ++i) {
const int last_byte = (i + 1U) == size;
status = soft_i2c_read_byte(bus, &data[i], last_byte);
if (status != SOFT_I2C_STATUS_OK) {
goto done;
}
}
done:
if (started) {
soft_i2c_stop(bus);
}
return status;
}
/* 先写后读的组合事务，实现典型寄存器访问 */
soft_i2c_status_t soft_i2c_master_write_read(soft_i2c_bus_t *bus, uint8_t address,
const uint8_t *tx_data, size_t tx_size,
uint8_t *rx_data, size_t rx_size)
{
if (((tx_data == NULL) && (tx_size > 0U)) ||
((rx_data == NULL) && (rx_size > 0U))) {
return SOFT_I2C_STATUS_INVALID_PARAM;
}
soft_i2c_status_t status = soft_i2c_prepare_bus(bus);
if (status != SOFT_I2C_STATUS_OK) {
return status;
}
int started = 0;
if (tx_size > 0U) {
status = soft_i2c_start(bus);
if (status != SOFT_I2C_STATUS_OK) {
goto cleanup;
}
started = 1;
status = soft_i2c_write_byte(bus, address & (uint8_t)~0x01U);
if (status != SOFT_I2C_STATUS_OK) {
goto cleanup;
}
for (size_t i = 0; i < tx_size; ++i) {
status = soft_i2c_write_byte(bus, tx_data[i]);
if (status != SOFT_I2C_STATUS_OK) {
goto cleanup;
}
}
}
if (rx_size > 0U) {
if (!started) {
status = soft_i2c_start(bus);
if (status != SOFT_I2C_STATUS_OK) {
goto cleanup;
}
started = 1;
} else {
status = soft_i2c_repeated_start(bus);
if (status != SOFT_I2C_STATUS_OK) {
goto cleanup;
}
}
status = soft_i2c_write_byte(bus, address | 0x01U);
if (status != SOFT_I2C_STATUS_OK) {
goto cleanup;
}
for (size_t i = 0; i < rx_size; ++i) {
const int last_byte = (i + 1U) == rx_size;
status = soft_i2c_read_byte(bus, &rx_data[i], last_byte);
if (status != SOFT_I2C_STATUS_OK) {
goto cleanup;
}
}
}
cleanup:
if (started) {
soft_i2c_stop(bus);
}
return status;
}
/* 确保总线已经初始化，必要时报错 */
static soft_i2c_status_t soft_i2c_prepare_bus(soft_i2c_bus_t *bus)
{
if (bus == NULL) {
return SOFT_I2C_STATUS_INVALID_PARAM;
}
if (bus->initialized == 0U) {
return soft_i2c_bus_init(bus);
}
return SOFT_I2C_STATUS_OK;
}
/* 根据配置执行半周期延时，可自定义回调或默认NOP循环 */
static void soft_i2c_delay(const soft_i2c_bus_t *bus)
{
if ((bus != NULL) && (bus->delay_fn != NULL)) {
bus->delay_fn(bus->delay_ticks, bus->delay_ctx);
return;
}
uint32_t ticks = (bus == NULL || bus->delay_ticks == 0U) ? SOFT_I2C_DEFAULT_DELAY_TICKS : bus->delay_ticks;
for (volatile uint32_t i = 0; i < ticks; ++i) {
__NOP();
}
}
/* 设置SCL电平并处理clock stretching */
static soft_i2c_status_t soft_i2c_drive_scl(soft_i2c_bus_t *bus, soft_i2c_pin_state_t state)
{
soft_i2c_status_t status = bus->scl.write(bus->scl.ctx, state);
if (status != SOFT_I2C_STATUS_OK) {
return status;
}
if (state == SOFT_I2C_PIN_SET) {
uint32_t timeout = (bus->stretch_timeout_ticks == 0U)
? SOFT_I2C_DEFAULT_STRETCH_TICKS
: bus->stretch_timeout_ticks;
while (bus->scl.read(bus->scl.ctx) == SOFT_I2C_PIN_RESET) {
if (timeout-- == 0U) {
return SOFT_I2C_STATUS_TIMEOUT;
}
}
}
return SOFT_I2C_STATUS_OK;
}
/* 设置SDA电平 */
static soft_i2c_status_t soft_i2c_drive_sda(soft_i2c_bus_t *bus, soft_i2c_pin_state_t state)
{
return bus->sda.write(bus->sda.ctx, state);
}
/* 产生I2C起始条件 */
static soft_i2c_status_t soft_i2c_start(soft_i2c_bus_t *bus)
{
soft_i2c_status_t status = soft_i2c_drive_sda(bus, SOFT_I2C_PIN_SET);
if (status != SOFT_I2C_STATUS_OK) {
return status;
}
status = soft_i2c_drive_scl(bus, SOFT_I2C_PIN_SET);
if (status != SOFT_I2C_STATUS_OK) {
return status;
}
soft_i2c_delay(bus);
status = soft_i2c_drive_sda(bus, SOFT_I2C_PIN_RESET);
if (status != SOFT_I2C_STATUS_OK) {
return status;
}
soft_i2c_delay(bus);
status = soft_i2c_drive_scl(bus, SOFT_I2C_PIN_RESET);
if (status != SOFT_I2C_STATUS_OK) {
return status;
}
soft_i2c_delay(bus);
return SOFT_I2C_STATUS_OK;
}
/* 产生重复起始条件，用于读写切换 */
static soft_i2c_status_t soft_i2c_repeated_start(soft_i2c_bus_t *bus)
{
soft_i2c_status_t status = soft_i2c_drive_sda(bus, SOFT_I2C_PIN_SET);
if (status != SOFT_I2C_STATUS_OK) {
return status;
}
soft_i2c_delay(bus);
status = soft_i2c_drive_scl(bus, SOFT_I2C_PIN_SET);
if (status != SOFT_I2C_STATUS_OK) {
return status;
}
soft_i2c_delay(bus);
status = soft_i2c_drive_sda(bus, SOFT_I2C_PIN_RESET);
if (status != SOFT_I2C_STATUS_OK) {
return status;
}
soft_i2c_delay(bus);
status = soft_i2c_drive_scl(bus, SOFT_I2C_PIN_RESET);
if (status != SOFT_I2C_STATUS_OK) {
return status;
}
soft_i2c_delay(bus);
return SOFT_I2C_STATUS_OK;
}
/* 产生停止条件，将总线释放到空闲 */
static void soft_i2c_stop(soft_i2c_bus_t *bus)
{
soft_i2c_drive_sda(bus, SOFT_I2C_PIN_RESET);
soft_i2c_delay(bus);
soft_i2c_drive_scl(bus, SOFT_I2C_PIN_SET);
soft_i2c_delay(bus);
soft_i2c_drive_sda(bus, SOFT_I2C_PIN_SET);
soft_i2c_delay(bus);
}
/* 写入单字节并读取对方ACK */
static soft_i2c_status_t soft_i2c_write_byte(soft_i2c_bus_t *bus, uint8_t value)
{
for (int8_t bit = 7; bit >= 0; --bit) {
soft_i2c_pin_state_t state = ((value >> bit) & 0x01U) ? SOFT_I2C_PIN_SET : SOFT_I2C_PIN_RESET;
soft_i2c_status_t status = soft_i2c_drive_sda(bus, state);
if (status != SOFT_I2C_STATUS_OK) {
return status;
}
soft_i2c_delay(bus);
status = soft_i2c_drive_scl(bus, SOFT_I2C_PIN_SET);
if (status != SOFT_I2C_STATUS_OK) {
return status;
}
soft_i2c_delay(bus);
status = soft_i2c_drive_scl(bus, SOFT_I2C_PIN_RESET);
if (status != SOFT_I2C_STATUS_OK) {
return status;
}
soft_i2c_delay(bus);
}
soft_i2c_status_t status = soft_i2c_drive_sda(bus, SOFT_I2C_PIN_SET);
if (status != SOFT_I2C_STATUS_OK) {
return status;
}
soft_i2c_delay(bus);
status = soft_i2c_drive_scl(bus, SOFT_I2C_PIN_SET);
if (status != SOFT_I2C_STATUS_OK) {
return status;
}
soft_i2c_delay(bus);
soft_i2c_pin_state_t ack = bus->sda.read(bus->sda.ctx);
status = soft_i2c_drive_scl(bus, SOFT_I2C_PIN_RESET);
if (status != SOFT_I2C_STATUS_OK) {
return status;
}
soft_i2c_delay(bus);
return (ack == SOFT_I2C_PIN_RESET) ? SOFT_I2C_STATUS_OK : SOFT_I2C_STATUS_ERROR;
}
/* 读取单字节，并根据last_byte决定发送ACK或NACK */
static soft_i2c_status_t soft_i2c_read_byte(soft_i2c_bus_t *bus, uint8_t *value, int last_byte)
{
uint8_t result = 0U;
soft_i2c_status_t status = soft_i2c_drive_sda(bus, SOFT_I2C_PIN_SET);
if (status != SOFT_I2C_STATUS_OK) {
return status;
}
for (int8_t bit = 7; bit >= 0; --bit) {
status = soft_i2c_drive_scl(bus, SOFT_I2C_PIN_SET);
if (status != SOFT_I2C_STATUS_OK) {
return status;
}
soft_i2c_delay(bus);
if (bus->sda.read(bus->sda.ctx) == SOFT_I2C_PIN_SET) {
result |= (uint8_t)(1U << bit);
}
status = soft_i2c_drive_scl(bus, SOFT_I2C_PIN_RESET);
if (status != SOFT_I2C_STATUS_OK) {
return status;
}
soft_i2c_delay(bus);
}
status = soft_i2c_drive_sda(bus, last_byte ? SOFT_I2C_PIN_SET : SOFT_I2C_PIN_RESET);
if (status != SOFT_I2C_STATUS_OK) {
return status;
}
soft_i2c_delay(bus);
status = soft_i2c_drive_scl(bus, SOFT_I2C_PIN_SET);
if (status != SOFT_I2C_STATUS_OK) {
return status;
}
soft_i2c_delay(bus);
status = soft_i2c_drive_scl(bus, SOFT_I2C_PIN_RESET);
if (status != SOFT_I2C_STATUS_OK) {
return status;
}
soft_i2c_delay(bus);
soft_i2c_drive_sda(bus, SOFT_I2C_PIN_SET);
if (value != NULL) {
*value = result;
}
return SOFT_I2C_STATUS_OK;
}
