添加 MQ-2 传感器支持，初始化 ADC 通道并读取气体浓度

components/MQ-2/MQ-2.c

@@ -0,0 +1,67 @@
+#include "MQ-2.h"
+
+#include "esp_adc/adc_oneshot.h"
+#include "esp_check.h"
+
+#define MQ2_ADC_UNIT ADC_UNIT_1
+#define MQ2_ADC_CHANNEL ADC_CHANNEL_7
+#define MQ2_SAMPLE_COUNT 8
+
+static const char *TAG = "MQ2";
+static adc_oneshot_unit_handle_t s_adc_handle = NULL;
+static bool s_inited = false;
+
+esp_err_t mq2_init(void)
+{
+	if (s_inited) {
+		return ESP_OK;
+	}
+
+	adc_oneshot_unit_init_cfg_t init_cfg = {
+		.unit_id = MQ2_ADC_UNIT,
+		.ulp_mode = ADC_ULP_MODE_DISABLE,
+	};
+	ESP_RETURN_ON_ERROR(adc_oneshot_new_unit(&init_cfg, &s_adc_handle), TAG, "adc new unit failed");
+
+	adc_oneshot_chan_cfg_t chan_cfg = {
+		.atten = ADC_ATTEN_DB_12,
+		.bitwidth = ADC_BITWIDTH_DEFAULT,
+	};
+	ESP_RETURN_ON_ERROR(adc_oneshot_config_channel(s_adc_handle, MQ2_ADC_CHANNEL, &chan_cfg),
+						TAG, "adc channel config failed");
+
+	s_inited = true;
+	return ESP_OK;
+}
+
+esp_err_t mq2_read_raw(int *raw_out)
+{
+	ESP_RETURN_ON_FALSE(raw_out != NULL, ESP_ERR_INVALID_ARG, TAG, "raw_out is null");
+	ESP_RETURN_ON_FALSE(s_inited, ESP_ERR_INVALID_STATE, TAG, "mq2 not inited");
+
+	int sum = 0;
+	for (int i = 0; i < MQ2_SAMPLE_COUNT; ++i) {
+		int sample = 0;
+		ESP_RETURN_ON_ERROR(adc_oneshot_read(s_adc_handle, MQ2_ADC_CHANNEL, &sample),
+							TAG, "adc read failed");
+		sum += sample;
+	}
+
+	*raw_out = sum / MQ2_SAMPLE_COUNT;
+	return ESP_OK;
+}
+
+esp_err_t mq2_read_percent(float *percent_out)
+{
+	ESP_RETURN_ON_FALSE(percent_out != NULL, ESP_ERR_INVALID_ARG, TAG, "percent_out is null");
+
+	int raw = 0;
+	ESP_RETURN_ON_ERROR(mq2_read_raw(&raw), TAG, "read raw failed");
+	*percent_out = (raw * 100.0f) / 4095.0f;
+	return ESP_OK;
+}
+
+bool mq2_is_alarm(float percent, float threshold_percent)
+{
+	return percent >= threshold_percent;
+}