Move source code to /firmware and fix build paths

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;
+}