158 lines
3.6 KiB
C
158 lines
3.6 KiB
C
#include <stdint.h>
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#include <stdbool.h>
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#include <string.h>
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#include "esp_err.h"
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#include "esp_log.h"
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#include "esp_timer.h"
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#include "onewire_bus.h"
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#include "board.h"
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#include "hal_temp.h"
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#define TEMP_OFFSET 0.4f
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#define CMD_SKIP_ROM 0xCC
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#define CMD_CONVERT_T 0x44
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#define CMD_READ_SCRATCH 0xBE
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static const char *TAG = "temp";
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#define TEMP_CONV_MS 750
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typedef enum {
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T_START,
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T_WAIT,
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} temp_state_t;
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static onewire_bus_handle_t s_bus;
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static bool s_inited;
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static float s_last_c;
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static bool s_last_ok;
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static temp_state_t s_state = T_START;
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static uint32_t s_deadline_ms;
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static uint32_t now_ms(void)
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{
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return (uint32_t)(esp_timer_get_time() / 1000ULL);
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}
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static bool scratch_valid(const uint8_t *sp)
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{
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/* DS18B20 CRC8 over first 8 bytes, poly 0x8C reflected. */
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uint8_t crc = 0;
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for (int i = 0; i < 8; i++) {
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uint8_t in = sp[i];
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for (int b = 0; b < 8; b++) {
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uint8_t mix = (crc ^ in) & 0x01;
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crc >>= 1;
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if (mix) {
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crc ^= 0x8C;
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}
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in >>= 1;
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}
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}
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return crc == sp[8];
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}
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void hal_temp_tick(void)
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{
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if (s_bus == NULL) {
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s_last_ok = false;
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return;
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}
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uint32_t now = now_ms();
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if (s_state == T_START) {
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if (now < s_deadline_ms) {
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return;
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}
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if (onewire_bus_reset(s_bus) != ESP_OK) {
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s_last_ok = false;
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s_deadline_ms = now + TEMP_CONV_MS;
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return;
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}
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uint8_t conv[2] = {CMD_SKIP_ROM, CMD_CONVERT_T};
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if (onewire_bus_write_bytes(s_bus, conv, 2) != ESP_OK) {
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s_last_ok = false;
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s_deadline_ms = now + TEMP_CONV_MS;
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return;
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}
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s_deadline_ms = now + TEMP_CONV_MS;
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s_state = T_WAIT;
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return;
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}
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/* T_WAIT */
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if (now < s_deadline_ms) {
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return;
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}
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s_state = T_START;
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s_deadline_ms = now;
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if (onewire_bus_reset(s_bus) != ESP_OK) {
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s_last_ok = false;
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s_deadline_ms = now + TEMP_CONV_MS;
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return;
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}
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uint8_t rd[2] = {CMD_SKIP_ROM, CMD_READ_SCRATCH};
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if (onewire_bus_write_bytes(s_bus, rd, 2) != ESP_OK) {
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s_last_ok = false;
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s_deadline_ms = now + TEMP_CONV_MS;
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return;
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}
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uint8_t sp[9];
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memset(sp, 0, sizeof(sp));
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if (onewire_bus_read_bytes(s_bus, sp, sizeof(sp)) != ESP_OK) {
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s_last_ok = false;
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s_deadline_ms = now + TEMP_CONV_MS;
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return;
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}
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if (!scratch_valid(sp)) {
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s_last_ok = false;
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s_deadline_ms = now + TEMP_CONV_MS;
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return;
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}
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int16_t raw = (int16_t)((uint16_t)sp[0] | ((uint16_t)sp[1] << 8));
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float t = ((float)raw) / 16.0f + TEMP_OFFSET;
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s_last_c = t;
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s_last_ok = true;
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}
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void hal_temp_init(void)
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{
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if (s_inited) {
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return;
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}
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gpio_num_t pin = board_pin_temp();
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if (pin == GPIO_NUM_NC) {
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ESP_LOGW(TAG, "no temp pin on this board");
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s_inited = true;
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return;
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}
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onewire_bus_config_t bus_config = {
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.bus_gpio_num = pin,
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.flags = {
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.en_pull_up = true,
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},
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};
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onewire_bus_rmt_config_t rmt_config = {
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.max_rx_bytes = 10,
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};
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if (onewire_new_bus_rmt(&bus_config, &rmt_config, &s_bus) != ESP_OK) {
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s_bus = NULL;
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ESP_LOGE(TAG, "onewire_bus install failed pin=%d", pin);
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}
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s_last_ok = false;
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s_last_c = 0.0f;
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s_inited = true;
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ESP_LOGI(TAG, "init onewire_bus pin=%d offset=%.1f", pin, (double)TEMP_OFFSET);
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}
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esp_err_t hal_temp_read_c(float *out)
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{
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if (!s_last_ok) {
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return ESP_FAIL;
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}
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if (out != NULL) {
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*out = s_last_c;
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}
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return ESP_OK;
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}
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