Move source code to /firmware and fix build paths

firmware/atmega/source/adc.c

@@ -0,0 +1,27 @@
+#include <stdint.h>
+#include <avr/io.h>
+#include <avr/interrupt.h>
+
+void adcInit(void) {
+    // Set reference voltage to AVcc (REFS0 = 1, REFS1 = 0)
+    ADMUX = (1 << REFS0);
+
+    // Enable ADC and set prescaler to 128 (for 16 MHz clock, gives 125 kHz ADC clock)
+    ADCSRA = (1 << ADEN) | (1 << ADPS2) | (1 << ADPS1) | (1 << ADPS0);
+}
+
+uint16_t adcRead(uint8_t channel) {
+    // Select ADC pin (A0-A7) by setting MUX bits in ADMUX
+    // Pins A6 and A7 would make an 8 sensor array possible (for large vases).
+    // Achievable only when using the 328p as a DIP, through port C (PC6, PC7)
+    ADMUX = (ADMUX & 0xF8) | (channel & 0x07);
+
+    // Start conversion
+    ADCSRA |= (1 << ADSC);
+
+    // Wait for conversion to complete (ADSC becomes '0' when done)
+    while (ADCSRA & (1 << ADSC));
+
+    // Read ADC (reading order: ADCL --> ADCH)
+    return ADC;
+}

firmware/atmega/source/main.c

@@ -0,0 +1,48 @@
+#include <stdint.h>
+#include <stdbool.h>
+#include <avr/sleep.h>
+#include <avr/wdt.h>
+#include <avr/interrupt.h>
+#include "moisture.h"
+#include "adc.h"
+
+ISR(WDT_vect) {
+    triggerSensorsRead();
+}
+
+void watchdogs(void) {
+    cli();
+    MCUSR &= ~(1 << WDRF);
+    WDTCSR |= (1 << WDCE) | (1 << WDE);
+    WDTCSR = (1 << WDIE) | (1 << WDP3) | (1 << WDP0);
+    sei();
+}
+
+void enterSleep(void) {
+    set_sleep_mode(SLEEP_MODE_IDLE);
+    sleep_enable();
+    sleep_cpu();
+    sleep_disable();
+}
+
+void setup(void) {
+    adcInit();
+    initMoistureSensors();
+    watchdogs();
+}
+
+int main(void) {
+    setup();
+
+    while(true) {
+        if (readSensors) {
+            int16_t result = readMoisture();
+
+            //TODO: send result to esp32
+        }
+        // readFromEsp()
+        // if esp tells to water plants: waterPlants()
+        enterSleep();
+    }
+    return 0;
+}

firmware/atmega/source/moisture.c

@@ -0,0 +1,62 @@
+#include <stdint.h>
+#include <stdbool.h>
+#include <avr/io.h>
+#include <avr/interrupt.h>
+#include "moisture.h"
+#include "config.h"
+#include "adc.h"
+
+volatile bool readSensors = false;
+
+void initMoistureSensors(void) {
+    // Set as input
+    DDRC &= ~((1 << MOISTURE_SENSOR_A0) |
+              (1 << MOISTURE_SENSOR_A1) |
+              (1 << MOISTURE_SENSOR_A2) |
+              (1 << MOISTURE_SENSOR_A3) |
+              (1 << MOISTURE_SENSOR_A4) |
+              (1 << MOISTURE_SENSOR_A5)) ;
+              //(1 << MOISTURE_SENSOR_A6) |
+              //(1 << MOISTURE_SENSOR_A7));
+    // Disable pullup
+    PORTC &= ~((1 << MOISTURE_SENSOR_A0) |
+               (1 << MOISTURE_SENSOR_A1) |
+               (1 << MOISTURE_SENSOR_A2) |
+               (1 << MOISTURE_SENSOR_A3) |
+               (1 << MOISTURE_SENSOR_A4) |
+               (1 << MOISTURE_SENSOR_A5)) ;
+               //(1 << MOISTURE_SENSOR_A6) |
+               //(1 << MOISTURE_SENSOR_A7));
+}
+
+void triggerSensorsRead(void) {
+    readSensors = true;
+}
+
+int16_t moistureSensorsAverage(int8_t sensorPin) {
+    int16_t sum = 0;
+    for (int i = 0; i < SENSOR_READINGS; i++) {
+        sum += adcRead(sensorPin);
+        //TODO: implement variance check (if over a certain variance discard measurements for this cycle)
+        //TODO: maybe add a small delay using watchdog here?
+        //TODO IMPORTANT: if value < 1 or > 1022, discard that measurement
+    }
+    return sum / SENSOR_READINGS;
+}
+
+int16_t readMoisture(void) {
+    uint8_t sensorPins[SENSORS_NUM] = { MOISTURE_SENSOR_A0, MOISTURE_SENSOR_A1,
+                                        MOISTURE_SENSOR_A2, MOISTURE_SENSOR_A3,
+                                        MOISTURE_SENSOR_A4, MOISTURE_SENSOR_A5 };
+                                        //MOISTURE_SENSOR_A6, MOISTURE_SENSOR_A7 };
+
+    int16_t overallSum = 0;
+
+    for (int i = 0; i < SENSORS_NUM; i++) {
+        int16_t sensorAverage = moistureSensorsAverage(sensorPins[i]);
+        //TODO: if a sensor gives 0 or 1023, discard that sensor entirely (means it is disconnected or not working)
+        overallSum += sensorAverage;
+    }
+
+    return overallSum / SENSORS_NUM;
+}