feat: add inital boot

mcu-server-watchdog.ino

@@ -1,10 +1,13 @@
-const int HEARTBEAT_MAX_DELAY_MILLIS = 20000;  //this is coupled to the HEARTBEAT_INTERVAL in src/main.rs
+const int HEARTBEAT_REBOOT_DELAY_MILLIS = 20000;  //this is coupled to the HEARTBEAT_INTERVAL in src/main.rs
-const int PIN_SWITCH = 2;
+const int HEARTBEAT_BOOT_DELAY_MILLIS = 60000;
+const int PIN_REBOOT = 2;
+const int PIN_BOOT = 3;
 
 unsigned long startTimeMillis;
 void setup() {
   Serial.begin(9600);
-  pinMode(PIN_SWITCH, OUTPUT);
+  pinMode(PIN_REBOOT, OUTPUT);
+  pinMode(PIN_BOOT, OUTPUT);
   waitForSerial();
   //NOTE might want to replace this initialization with a check in the first loop, so we dont instantly reboot
   startTimeMillis = millis(); 
@@ -12,9 +15,7 @@ void setup() {
 }
 
 void loop(){
-  unsigned long currentTimeMillis = millis();
+  if (millis() - startTimeMillis > HEARTBEAT_REBOOT_DELAY_MILLIS){pin_switch(PIN_REBOOT);}
-  unsigned long tickMillis = currentTimeMillis - startTimeMillis;
-  if (tickMillis > HEARTBEAT_MAX_DELAY_MILLIS){rst();}
   if (Serial.available() > 0) { // if something has been written to the serial port
     startTimeMillis = millis();
     clearSerial();
@@ -22,12 +23,12 @@ void loop(){
 }
 
 
-void rst(){
+void pin_switch(int pin){
   //TODO connect the RST pins on the motherboard
   Serial.println("Error!");
-  digitalWrite(PIN_SWITCH, LOW);
+  digitalWrite(pin, LOW);
   delay(500);
-  digitalWrite(PIN_SWITCH, HIGH);
+  digitalWrite(pin, HIGH);
   waitForSerial();
 }
 
@@ -35,7 +36,12 @@ void rst(){
 busy wait for first serial input
 */
 void waitForSerial(){
-    while(Serial.available() == 0){}
+    while(Serial.available() == 0){
+    //check if we may need to initiate a normal boot instead of a reboot, e.g. after a power outage
+    if (millis() - startTimeMillis > HEARTBEAT_BOOT_DELAY_MILLIS){
+      pin_switch(PIN_BOOT);
+    }
+    }
 }
 
 void clearSerial(){