add hardware watchdog feature

Firmware/.gitignore

@@ -0,0 +1 @@
+build*

Firmware/Zero2Go-Omini/Dockerfile

@@ -0,0 +1,31 @@
+FROM ubuntu:19.10
+
+RUN apt-get -yq update \
+ && apt-get -yq --no-install-suggests --no-install-recommends install \
+    wget \
+    git \
+    avrdude \
+    python-serial \
+    xz-utils \
+    ca-certificates \
+    make \
+ && apt-get clean \
+ && rm -rf /var/lib/apt/lists/*
+
+RUN wget https://downloads.arduino.cc/arduino-1.8.10-linux64.tar.xz \
+ && tar xf *.tar.xz -C /opt \
+ && rm *.tar.xz
+
+RUN git clone https://github.com/sudar/Arduino-Makefile -b 1.5.2 /opt/arduino-mk
+
+RUN git clone https://github.com/SpenceKonde/ATTinyCore.git -b v1.1.4 /opt/ATTinyCore
+
+RUN git clone https://github.com/orangkucing/WireS.git /opt/WireS \
+  && cd /opt/WireS \
+  && git reset --hard 776ffa23b6b9b8ae17b21e10357e22b09e7e9510
+
+RUN git clone https://github.com/orangkucing/analogComp /opt/analogComp
+
+WORKDIR /src
+
+CMD ["make"]

Firmware/Zero2Go-Omini/Makefile

@@ -0,0 +1,16 @@
+TARGET = Zero2Go-Omini.ino
+ARDUINO_DIR = /opt/arduino-1.8.10
+USER_LIB_PATH = /opt
+
+# Programmer type:
+ISP_PROG = usbasp
+
+# https://github.com/SpenceKonde/ATTinyCore (1.5+)
+ALTERNATE_CORE = ATTinyCore
+ALTERNATE_CORE_PATH = /opt/ATTinyCore
+BOARD_TAG = attinyx41
+BOARD_SUB = 841
+F_CPU = 8000000L
+
+# Path to the Arduino Makefile
+include /opt/arduino-mk/Arduino.mk

Firmware/Zero2Go-Omini/Zero2Go-Omini.ino

@@ -6,6 +6,7 @@
 #include <core_timers.h>
 #include <analogComp.h>
 #include <avr/sleep.h>
+#include <util/delay.h>
 #include <WireS.h>
 #include <EEPROM.h>
 
@@ -38,8 +39,9 @@
 #define I2C_CONF_BULK_ALWAYS_ON   13  // always enable bulk converter: 1=yes, 0=no
 #define I2C_CONF_POWER_CUT_DELAY  14  // the delay (x10) before power cut: default=50 (5 sec)
 #define I2C_CONF_RECOVERY_VOLTAGE 15  // voltage (x10) that triggers recovery, 255=disabled
+#define I2C_CONF_WATCHDOG_TIMEOUT 16  // set watchdog timeout, reset watchdog, 0=disabled
 
-#define I2C_REG_COUNT   16            // number of I2C registers
+#define I2C_REG_COUNT   17            // number of I2C registers
 
 volatile byte i2cReg[I2C_REG_COUNT];
 
@@ -63,6 +65,28 @@ volatile unsigned long buttonStateChangeTime = 0;
 
 volatile unsigned long voltageQueryTime = 0;
 
+volatile int watchdogCounter = 0;
+
+void timer1_enable();
+void timer2_enable();
+void cutPower();
+void powerOn();
+void redLightOn();
+void suggestShutdown();
+void redLightOff();
+void initializeRegisters();
+void updateRegister(int index, byte value);
+float getVoltage(int pin);
+int getIntegerPart(float v);
+int getDecimalPart(float v);
+unsigned int getPowerCutPreloadTimer();
+void receiveEvent(int count);
+boolean addressEvent(uint16_t slaveAddress, uint8_t startCount);
+void requestEvent();
+void comparatorStatusChanged();
+void sleep();
+void resetWatchdog();
+
 void setup() {
 
   // initialize pin states and make sure power is cut
@@ -106,6 +130,11 @@ void setup() {
   // enable Timer1
   timer1_enable();
 
+  // enable watchdog
+  if (i2cReg[I2C_CONF_WATCHDOG_TIMEOUT]) {
+    resetWatchdog();
+  }
+
   // enable comparator
   analogComparator.setOn(INTERNAL_REFERENCE, AIN1);
   analogComparator.enableInterrupt(comparatorStatusChanged, CHANGE);
@@ -121,6 +150,7 @@ void setup() {
   } else {
     sleep();    // sleep and wait for button action
   }
+
 }
 
 
@@ -175,6 +205,8 @@ void initializeRegisters() {
   i2cReg[I2C_CONF_POWER_CUT_DELAY] = 50;
   i2cReg[I2C_CONF_RECOVERY_VOLTAGE] = 255;
 
+  i2cReg[I2C_CONF_WATCHDOG_TIMEOUT] = 0;
+
   // make sure product name is stored
   EEPROM.update(0, 'Z');
   EEPROM.update(1, 'e');
@@ -238,9 +270,14 @@ void timer1_disable() {
   bitClear(TIMSK1, TOIE1);
 }
 
+void timer2_disable() {
+  // disable Timer2 overflow interrupt:
+  bitClear(TIMSK2, TOIE2);
+}
 
 void sleep() {
   timer1_disable();                       // disable Timer1
+  timer2_disable();
   ADCSRA &= ~_BV(ADEN);                   // ADC off
   set_sleep_mode(SLEEP_MODE_PWR_DOWN);    // power-down mode 
   watchdog_enable();                      // enable watchdog
@@ -466,6 +503,22 @@ ISR (TIM1_OVF_vect) {
 }
 
 
+// timer2 overflow interrupt routine
+ISR (TIM2_OVF_vect) {
+  // overflow in 8s
+  TCNT2 = 3035;
+  watchdogCounter++;
+  // minimum watchdog timeout is 1m20s
+  if (watchdogCounter >= (i2cReg[I2C_CONF_WATCHDOG_TIMEOUT] + 9)){
+    // watchdog timeout, trigger a reboot
+    watchdogCounter = 0;
+    cutPower();
+    _delay_ms (5000);
+    powerOn();
+  }
+}
+
+
 // analog comparator interrupt routine
 void comparatorStatusChanged() {
   bulkOrBoost = ((ACSR0A & (1<<ACO)) == 0);
@@ -475,14 +528,40 @@ void comparatorStatusChanged() {
   }
 }
 
+void resetWatchdog() {
+  watchdogCounter = 0;
+  // overflow in 8s
+  TCNT2 = 3035;
+
+  // initialize Timer2
+  TCCR2A = 0;    // set entire TCCR1A register to 0
+  TCCR2B = 0;    // set entire TCCR1B register to 0
+
+  if (i2cReg[I2C_CONF_WATCHDOG_TIMEOUT]) {
+    // enable Timer2 overflow interrupt:
+    bitSet(TIMSK2, TOIE2);
+    // set 1024 prescaler
+    bitSet(TCCR2B, CS12);
+    bitSet(TCCR2B, CS10);
+  }
+
+  redLightOn();
+  _delay_ms(50);
+  redLightOff();
+}
 
 // update I2C register, save to EEPROM if it is configuration
 void updateRegister(int index, byte value) {
-  i2cReg[index] = value;
-  if (index >= I2C_CONF_ADDRESS) {
-    EEPROM.update(index, value);
+  if (i2cReg[index] != value) {
+    i2cReg[index] = value;
+    if (index >= I2C_CONF_ADDRESS) {
+      EEPROM.update(index, value);
+    }
   }
   if (index == I2C_CONF_BULK_ALWAYS_ON) {
     powerOn();
   }
+  if (index == I2C_CONF_WATCHDOG_TIMEOUT) {
+    resetWatchdog();
+  }
 }

README.md

@@ -11,3 +11,19 @@ The firmware is compiled and uploaded to Zero2Go Omini via Arduino IDE (with ATT
 The software is written in BASH.
 
 More information about the firmware and software can be found in the user manual: http://www.uugear.com/doc/Zero2Go_Omini_UserManual.pdf
+
+# Firmware build instructions
+
+You can use the provided Dockerfile and Makefile (made with [Arduino-Makefile](https://github.com/sudar/Arduino-Makefile/)) to quickly set up a build environment with all the required dependencies.:
+
+```
+cd Firmware/Zero2Go-Omini
+docker build -t zero2go-omini .
+```
+
+The firmware can then be built with:
+
+```
+cd Firmware/Zero2Go-Omini
+docker run -ti -v $(pwd):/src zero2go-omini:latest
+```