save some implementation

main/hw/mcp3550.c

@@ -0,0 +1,118 @@
+#include "mcp3550.h"
+#include "mcp23018.h"
+#include "driver/gpio.h"
+#include <esp_timer.h>
+
+
+#define TAG_MICS "MICS_ADC"
+#define MCP3550_SPS 3.75f
+#define MCP3550_CONVERSION_MS ((int)(1000.0f / MCP3550_SPS)) // ~267ms
+#define MCP3550_TIMEOUT_MS 400
+
+#define ADC_COUNT 4
+const uint8_t adc_cs_pins[ADC_COUNT] = {
+    MCP_CS_ADC_NH3, MCP_CS_ADC_CO, MCP_CS_ADC_NO2, MCP_CS_ADC_UVC
+};
+
+
+spi_device_handle_t mcp3550_handle;
+
+void mcp3550_spi_init()
+{
+    spi_device_interface_config_t devcfg = {
+        .clock_speed_hz = 100000,
+        .mode = 0,
+        .spics_io_num = -1, // We handle CS manually
+        .queue_size = 1,
+    };
+
+    ESP_ERROR_CHECK(spi_bus_add_device(SPI2_HOST, &devcfg, &mcp3550_handle));
+
+    // Set MISO pin for input (needed for polling)
+    gpio_set_direction(MCP3550_MISO_GPIO, GPIO_MODE_INPUT);
+    mcp23018_set_pin(MCP23018_DEV_HANDLE, MCP_MICS_POWER, 1); // CS HIGH
+}
+
+
+int32_t mcp3550_read(uint8_t cs_pin)
+{
+    uint8_t rx_buf[4] = {0}; // 25 bits fits in 4 bytes
+
+    int64_t start = esp_timer_get_time(); // in microseconds
+    while (true) {
+        mcp23018_set_pin(MCP23018_DEV_HANDLE, cs_pin, 0); // CS LOW
+
+        spi_transaction_t trans = {
+            .length = 25,
+            .rx_buffer = rx_buf,
+        };
+
+        esp_err_t err = spi_device_transmit(mcp3550_handle, &trans);
+
+        mcp23018_set_pin(MCP23018_DEV_HANDLE, cs_pin, 1); // CS HIGH
+
+        if (err != ESP_OK) {
+            ESP_LOGE(TAG_MICS, "SPI transmit failed on CS pin %u", cs_pin);
+            return INT32_MIN;
+        }
+
+        bool dr = (rx_buf[0] & 0x80) != 0;
+        if (!dr) break;
+
+        if ((esp_timer_get_time() - start) > (MCP3550_TIMEOUT_MS * 1000)) {
+            ESP_LOGW(TAG_MICS, "Timeout waiting for DR=0 on CS pin %u", cs_pin);
+            return INT32_MIN;
+        }
+
+        vTaskDelay(pdMS_TO_TICKS(10)); // Wait before retrying
+    }
+
+    // Combine 22-bit result (drop DR + status bits)
+    uint32_t raw = ((rx_buf[0] & 0x3F) << 16) | (rx_buf[1] << 8) | rx_buf[2];
+
+    // Sign-extend 22-bit value
+    int32_t value = raw;
+    if (value & (1 << 21)) value |= 0xFFC00000;
+
+    return value;
+}
+
+
+float mcp3550_to_voltage(int32_t value, float vref)
+{
+    return ((float)value / (1 << 21)) * vref;
+}
+
+mics_adc_data_t mcp3550_read_all(float vref)
+{
+    mics_adc_data_t data;
+    int32_t raw[ADC_COUNT];
+    float volts[ADC_COUNT];
+
+    for (int i = 0; i < ADC_COUNT; i++) {
+        raw[i] = mcp3550_read(adc_cs_pins[i]);
+        vTaskDelay(pdMS_TO_TICKS(10)); // Wait before retrying
+        volts[i] = mcp3550_to_voltage(raw[i], vref);
+    }
+
+    data.raw_nh3 = raw[0]; data.volts_nh3 = volts[0];
+    data.raw_co  = raw[1]; data.volts_co  = volts[1];
+    data.raw_no2 = raw[2]; data.volts_no2 = volts[2];
+    data.raw_uvc = raw[3]; data.volts_uvc = volts[3];
+
+    return data;
+}
+
+void log_mics_adc_values(mics_adc_data_t *data)
+{
+    ESP_LOGI(TAG_MICS,
+             "ADC Readings:\n"
+             "  NH3  -> Raw: %8d, Voltage: %7.6f V\n"
+             "  CO   -> Raw: %8d, Voltage: %7.6f V\n"
+             "  NO2  -> Raw: %8d, Voltage: %7.6f V\n"
+             "  UVC  -> Raw: %8d, Voltage: %7.6f V",
+             data->raw_nh3, data->volts_nh3,
+             data->raw_co,  data->volts_co,
+             data->raw_no2, data->volts_no2,
+             data->raw_uvc, data->volts_uvc);
+}