calculate soil moisture on wake from deep sleep

1 files changed, 144 insertions, 17 deletions

diff --git a/ULPSoilMonitor.ino b/ULPSoilMonitor.ino
index f7ccdb1..ded644c 100644
--- a/ULPSoilMonitor.ino
+++ b/ULPSoilMonitor.ino
@@ -11,10 +11,34 @@
 #include "esp32/ulp.h"
 #include "ulp_soil.h"
 #include "ulptool.h"
+#include <math.h>
+
+#define ADC_FACTOR (3.5f)
+#define ADC_VCC_PIN (ADC2_CHANNEL_9)
 
 extern const uint8_t ulp_main_bin_start[] asm("_binary_ulp_main_bin_start");
 extern const uint8_t ulp_main_bin_end[]   asm("_binary_ulp_main_bin_end");
 
+struct {
+  float soil0;
+  float soil1;
+  float soil2;
+  float soil3;
+  float soil4;
+  float soil5;
+} sensor_offset, sensor_gradient;
+
+struct soil_data {
+  float vcc;
+  float soil0;
+  float soil1;
+  float soil2;
+  float soil3;
+  float soil4;
+  float soil5;
+  bool valid = false;
+} soil;
+
 /* This function is called once after power-on reset, to load ULP program into
    RTC memory and configure the ADC.
 */
@@ -25,27 +49,43 @@ static void init_ulp_program();
 */
 static void start_ulp_program();
 
+/* measures voltage on GPIO26 */
+static void measure_vcc();
+
+static void init_sensor_coefficients();
+
+static float soil_moisture(uint16_t adc_value, float vcc, float offset, float gradient);
+
+/* fills soil_data struct */
+static void calculate_soil_data();
+
+/* logs current soil_data */
+static void print_soil_data();
+
 void setup() {
   Serial.begin(115200);
-  delay(100);
+
   esp_sleep_wakeup_cause_t cause = esp_sleep_get_wakeup_cause();
-  if (cause != ESP_SLEEP_WAKEUP_ULP) {
-    Serial.printf("Not ULP wakeup\n");
-    init_ulp_program();
-  } else {
+  if (cause == ESP_SLEEP_WAKEUP_ULP) {
+
     Serial.printf("Deep sleep wakeup\n");
     /* Count temperature form -5 ℃ , so ulp_temperature minus 5 */
     Serial.printf("max_diff:%d\n", (uint16_t)ulp_max_diff);
-    Serial.printf("Soil0:%d\n", (uint16_t)ulp_soil0);
-    Serial.printf("Soil1:%d\n", (uint16_t)ulp_soil1);
-    Serial.printf("Soil2:%d\n", (uint16_t)ulp_soil2);
-    Serial.printf("Soil3:%d\n", (uint16_t)ulp_soil3);
-    Serial.printf("Soil4:%d\n", (uint16_t)ulp_soil4);
-    Serial.printf("Soil5:%d\n", (uint16_t)ulp_soil5);
+
+    measure_vcc();
+    calculate_soil_data();
+    print_soil_data();
+
+  } else {
+
+    esp_err_t err = ulptool_load_binary(0, ulp_main_bin_start, (ulp_main_bin_end - ulp_main_bin_start) / sizeof(uint32_t));
+    ESP_ERROR_CHECK(err);
+
   }
+
   Serial.printf("Entering deep sleep\n\n");
   start_ulp_program();
-  ESP_ERROR_CHECK( esp_sleep_enable_ulp_wakeup() );
+  ESP_ERROR_CHECK(esp_sleep_enable_ulp_wakeup());
   esp_deep_sleep_start();
 }
 
@@ -55,10 +95,6 @@ void loop() {
 
 static void init_ulp_program()
 {
-  esp_err_t err = ulptool_load_binary(0, ulp_main_bin_start,
-                                  (ulp_main_bin_end - ulp_main_bin_start) / sizeof(uint32_t));
-  ESP_ERROR_CHECK(err);
-
   /* Configure ADC channel */
   adc1_ulp_enable();
   adc1_config_channel_atten(ADC1_CHANNEL_7, ADC_ATTEN_DB_0);
@@ -71,6 +107,7 @@ static void init_ulp_program()
 
   gpio_deep_sleep_hold_en();
 
+  /* Configure SENSOR_ENABLE */
   rtc_gpio_init(GPIO_NUM_25);
   rtc_gpio_set_direction(GPIO_NUM_25, RTC_GPIO_MODE_OUTPUT_ONLY);
   rtc_gpio_pullup_en(GPIO_NUM_25);
@@ -78,7 +115,7 @@ static void init_ulp_program()
   rtc_gpio_hold_en(GPIO_NUM_25);
 
   /* Set ULP wake up period to 1000ms */
-  ulp_set_wakeup_period(0, 10000 * 1000);
+  ulp_set_wakeup_period(0, 1000 * 1000);
 
   /* Disable pullup on GPIO15, in case it is connected to ground to suppress
      boot messages.
@@ -89,7 +126,97 @@ static void init_ulp_program()
 
 static void start_ulp_program()
 {
+  init_ulp_program();
+
   /* Start the program */
   esp_err_t err = ulp_run((&ulp_entry - RTC_SLOW_MEM) / sizeof(uint32_t));
   ESP_ERROR_CHECK(err);
 }
+
+static void measure_vcc()
+{
+  int raw;
+
+  gpio_reset_pin(GPIO_NUM_25);
+  gpio_pad_select_gpio(GPIO_NUM_25);
+  gpio_hold_dis(GPIO_NUM_25);
+  gpio_set_direction(GPIO_NUM_25, GPIO_MODE_OUTPUT_OD);
+  gpio_set_level(GPIO_NUM_25, 0);
+
+  vTaskDelay(10);
+
+  adc2_config_channel_atten(ADC_VCC_PIN, ADC_ATTEN_DB_0);
+  esp_err_t r = adc2_get_raw(ADC_VCC_PIN, ADC_WIDTH_12Bit, &raw);
+
+  gpio_set_level(GPIO_NUM_25, 1);
+  gpio_hold_en(GPIO_NUM_25);
+
+  if (r != ESP_OK) {
+    soil.vcc = NAN;
+    soil.valid = false;
+  } else {
+    float vcc = ((float)raw * ADC_FACTOR) / 4095;
+    soil.vcc = vcc;
+  }
+}
+
+static void  init_sensor_coefficients()
+{
+  sensor_offset.soil0 = 1.746;
+  sensor_offset.soil1 = 1.746;
+  sensor_offset.soil2 = 1.746;
+  sensor_offset.soil3 = 1.746;
+  sensor_offset.soil4 = 1.746;
+  sensor_offset.soil5 = 1.746;
+
+  sensor_gradient.soil0 = -2.849;
+  sensor_gradient.soil1 = -2.849;
+  sensor_gradient.soil2 = -2.849;
+  sensor_gradient.soil3 = -2.849;
+  sensor_gradient.soil4 = -2.849;
+  sensor_gradient.soil5 = -2.849;
+}
+
+static float soil_moisture(uint16_t adc_value, float vcc, float offset, float gradient)
+{
+  if (adc_value == 0.0) {
+    return NAN;
+  }
+  float moisture = 100.0 * (gradient * ((adc_value * ADC_FACTOR / 4095) / vcc) + offset);
+
+  if (moisture > 100.0)
+    moisture = 100.0;
+  else if (moisture < 0.0)
+    moisture = 0.0;
+
+  return moisture;
+}
+
+static void calculate_soil_data()
+{
+  if (isnan(soil.valid))
+    return;
+
+  init_sensor_coefficients();
+
+  soil.soil0 = soil_moisture(ulp_soil0, soil.vcc, sensor_offset.soil0, sensor_gradient.soil0);
+  soil.soil1 = soil_moisture(ulp_soil1, soil.vcc, sensor_offset.soil1, sensor_gradient.soil1);
+  soil.soil2 = soil_moisture(ulp_soil2, soil.vcc, sensor_offset.soil2, sensor_gradient.soil2);
+  soil.soil3 = soil_moisture(ulp_soil3, soil.vcc, sensor_offset.soil3, sensor_gradient.soil3);
+  soil.soil4 = soil_moisture(ulp_soil4, soil.vcc, sensor_offset.soil4, sensor_gradient.soil4);
+  soil.soil5 = soil_moisture(ulp_soil5, soil.vcc, sensor_offset.soil5, sensor_gradient.soil5);
+
+  soil.valid = true;
+}
+
+static void print_soil_data()
+{
+    Serial.printf("valid: %d\n", soil.valid);
+    Serial.printf("VCC: %f\n", soil.vcc);
+    Serial.printf("Soil0:%d -> %f\n", (uint16_t)ulp_soil0, soil.soil0);
+    Serial.printf("Soil1:%d -> %f\n", (uint16_t)ulp_soil1, soil.soil1);
+    Serial.printf("Soil2:%d -> %f\n", (uint16_t)ulp_soil2, soil.soil2);
+    Serial.printf("Soil3:%d -> %f\n", (uint16_t)ulp_soil3, soil.soil3);
+    Serial.printf("Soil4:%d -> %f\n", (uint16_t)ulp_soil4, soil.soil4);
+    Serial.printf("Soil5:%d -> %f\n", (uint16_t)ulp_soil5, soil.soil5);
+}