init

CMakeLists.txt

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+idf_component_register(SRCS
+  "main/esp32-gp2y.c"
+
+  INCLUDE_DIRS "include"
+)

README.md

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+# ESP32 GP2Y Dust Sensor
+
+## Install
+
+Designed to be used as an `esp-idf component`. Suggested usage is with  `git submodule`
+
+```
+git submodule add https://git.oit.cloud/morgan/esp32-gp2y.git components/esp32-gp2y/
+git submodule update --init
+```
+
+## API
+
+### `typedef gp2y_cfg_t`
+`float K` Sensitivity. Default: 0.5
+`float offset_voltage` Voltage level at 0ug/m3 dust. Defaults to 0.6v, dynamically lowers.
+`int8_t pin_led` Pin to pulse LED on.
+`adc1_channel_t adc_channel` ADC channel to read on. See IDF Guide to get pin to channel reference.
+`adc_unit_t adc_unit` ADC unit to read on.
+
+### `int32_t gp2y_read(gp2y_cfg_t *cfg, uint8_t samples)`
+Passing a pointer to `gp2y_cfg_t` and number of samples to take. 100 is a good starting point.
+
+
+## Example
+```
+#include <stdio.h>
+#include <unistd.h>
+#include "driver/gpio.h"
+#include "driver/adc.h"
+#include "esp32-gp2y.h"
+
+#define PIN_LED         5
+
+void app_main() {
+    gp2y_cfg_t gp2y_cfg = GP2Y_DEFAULT_CFG;
+    gp2y_cfg.adc_channel = channel;
+    gp2y_cfg.pin_led = PIN_LED;
+
+    gpio_config_t io_conf;
+    io_conf.intr_type = GPIO_INTR_DISABLE;
+    io_conf.mode = GPIO_MODE_OUTPUT;
+    io_conf.pin_bit_mask = (1ULL<<gp2y_cfg.pin_led);
+    io_conf.pull_down_en = 1;
+    io_conf.pull_up_en = 0;
+    gpio_config(&io_conf);
+
+    adc1_config_channel_atten(gp2y_cfg.adc_channel, ADC_ATTEN_DB_11);
+
+    while (1) {
+      printf("aqi: %dug/m3\n", gp2y_read(&gp2y_cfg, 100));
+      vTaskDelay(1000 / portTICK_PERIOD_MS);
+    }
+}
+```

include/esp32-gp2y.h

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+#ifndef _LORA32_H__
+#define _LORA32_H__
+
+typedef struct {
+  float K;
+  float offset_voltage;
+  int8_t pin_led;
+  adc1_channel_t adc_channel;
+  adc_unit_t adc_unit;
+} gp2y_cfg_t;
+
+#define GP2Y_DEFAULT_CFG {\
+  .K = 0.5,\
+  .offset_voltage = 0.6,\
+  .pin_led = -1,\
+  .adc_channel = -1\
+}
+
+int32_t gp2y_read(gp2y_cfg_t *cfg, uint8_t samples);
+
+#endif // _ESP32_GP2Y_H__

main/esp32-gp2y.c

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+#include <string.h>
+#include <unistd.h>
+
+#include "freertos/FreeRTOS.h"
+#include "freertos/task.h"
+
+#include "driver/adc.h"
+#include "driver/gpio.h"
+#include "esp_log.h"
+#include "esp32-gp2y.h"
+
+int32_t gp2y_read(gp2y_cfg_t *cfg, uint8_t samples) {
+  int32_t accum = 0;
+
+  for(uint8_t i = 0; i < samples; i++) {
+    portMUX_TYPE myMutex = portMUX_INITIALIZER_UNLOCKED;
+    taskENTER_CRITICAL(&myMutex);
+
+    gpio_set_level(cfg->pin_led, 0);
+    usleep(280);
+
+    accum += adc1_get_raw(cfg->adc_channel);
+
+    gpio_set_level(cfg->pin_led, 1);
+
+    taskEXIT_CRITICAL(&myMutex);
+
+    usleep(9620);
+  }
+
+  float avg_adc = (accum / samples);
+  float avg_volt = avg_adc / 4095 * 3.3;
+  float dV = avg_volt - cfg->offset_voltage;
+
+  // recalibrate offset_volt to lowest value seen
+  if(dV < 0) {
+    dV = 0;
+    cfg->offset_voltage = avg_volt;
+  }
+
+  return dV / cfg->K * 100.0;
+}