add hardware watchdog feature (implementation using the attiny watchdog)

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];
 
@@ -59,10 +61,35 @@ volatile boolean forcePowerCut = false;
 
 volatile boolean wakeupByWatchdog = false;
 
+volatile boolean watchdogEnabled = false;
+
 volatile unsigned long buttonStateChangeTime = 0;
 
 volatile unsigned long voltageQueryTime = 0;
 
+volatile unsigned long watchdogCounter = 0;
+
+void timer1_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 watchdog_enable();
+void watchdog_disable();
+
 void setup() {
 
   // initialize pin states and make sure power is cut
@@ -151,6 +178,14 @@ void loop() {
         suggestShutdown();
       }
     }
+
+    // the watchdog feature relies on the attiny watchdog
+    if (i2cReg[I2C_CONF_WATCHDOG_TIMEOUT] && !watchdogEnabled) {
+      watchdog_enable();
+    }
+    if (!i2cReg[I2C_CONF_WATCHDOG_TIMEOUT] && watchdogEnabled) {
+      watchdog_disable();
+    }
   }
 }
 
@@ -175,6 +210,8 @@ 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');
@@ -202,14 +239,18 @@ void watchdog_enable() {
   cli();
   WDTCSR |= _BV(WDIE);
   byte wdp = (i2cReg[I2C_CONF_BLINK_INTERVAL] > 9 ? 8 : i2cReg[I2C_CONF_BLINK_INTERVAL]);
+  wdp = wdp < 6 ? 6 : wdp;
   wdp = (((wdp & B00001000) << 2) | (wdp & B11110111));
   WDTCSR |= wdp;
   sei();
+  watchdogEnabled = true;
+  watchdogCounter = 0;
 }
 
 
 void watchdog_disable() {
   WDTCSR = 0;
+  watchdogEnabled = false;
 }
 
 
@@ -269,6 +310,9 @@ void sleep() {
         float vrec = ((float)i2cReg[I2C_CONF_RECOVERY_VOLTAGE]) / 10;
         if (vmax >= vrec) {
           wakeupByWatchdog = false;       // recovery from low voltage shutdown
+        } else {
+          // inhibit watchdog feature when voltage is too low
+          watchdogCounter = 0;
         }
       }
     }
@@ -406,7 +450,20 @@ void requestEvent() {
 
 // watchdog interrupt routine
 ISR (WDT_vect) {
-  // no need to do anything here
+  if (i2cReg[I2C_CONF_WATCHDOG_TIMEOUT]) {
+    // minimum timeout is 1m20s (10*8s)
+    unsigned long timeout = (i2cReg[I2C_CONF_WATCHDOG_TIMEOUT] + 9);
+    // timeout is made independant of the attiny watchdog prescaler
+    timeout *= (1 << (9 - (((WDTCSR & B00100000) >> 2) | (WDTCSR & B00000111))));
+    watchdogCounter++;
+    if (watchdogCounter >= timeout){
+      // watchdog timeout, trigger a reboot
+      watchdogCounter = 0;
+      cutPower();
+      _delay_ms (5000);
+      powerOn();
+    }
+  }
 }
 
 
@@ -475,14 +532,25 @@ void comparatorStatusChanged() {
   }
 }
 
+void resetWatchdog() {
+  watchdogCounter = 0;
+  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
+```