Added persistent storage! Every KWH the counter is stored.

Will change to a regular interval later on to reduce flash memory wear.

README.md

@@ -14,9 +14,9 @@ Done:
 - [X] Show (& calc) total consumption
 - [X] Use interrupts to get button input + pulses
 - [X] Use button input to switch between frames
+- [X] Persistent storage of KWh counter
 
 Future wishes:
-- [ ] Persistant storage of KWh counter
 - [ ] Add NTP time to sketch
 - [ ] Implement timezone offset, apply to current time
 - [ ] Keep track of total consumption for the day (and display this)
@@ -27,12 +27,14 @@ Future wishes:
 - [ ] Multi-SSID
 - [ ] Store measurements while there is no Wi-Fi connection
 - [ ] Work stand-alone (without Wi-Fi connection) without switching to Config mode
+- [ ] Reduce Flash memory wear by writing periodically instead of on every KWh increment
 
 ##Resources used
 * [SparkFun Eagle Libraries](https://github.com/sparkfun/SparkFun-Eagle-Libraries) by [SparkFun](https://github.com/sparkfun)
 * [TCRT5000 Eagle Library](https://github.com/mohamedpsx/Eagle-Libraries) by [mohamedpsx](https://github.com/mohamedpsx)
 
 * [esp8266-oled-ssd1306](https://github.com/squix78/esp8266-oled-ssd1306) by [squix78](https://github.com/squix78))
+* [EEPROMWriteAnything](http://playground.arduino.cc/Code/EEPROMWriteAnything) by the Arduino Community
 
 * [AirSensor Energy Monitor tutorial](http://www.airsensor.co.uk/component/zoo/item/energy-monitor.html)
 * [nongnu.org dtostrf](http://www.nongnu.org/avr-libc/user-manual/group__avr__stdlib.html#ga060c998e77fb5fc0d3168b3ce8771d42)

code/oakpowerboard/eepromanything.h

@@ -0,0 +1,24 @@
+#include <EEPROM.h>
+#include <Arduino.h>  // for type definitions
+
+template <class T> int EEPROM_writeAnything(int ee, const T& value)
+{
+    const byte* p = (const byte*)(const void*)&value;
+    unsigned int i;
+    EEPROM.begin(sizeof(value));
+    for (i = 0; i < sizeof(value); i++)
+          EEPROM.write(ee++, *p++);
+    EEPROM.end();
+    return i;
+}
+
+template <class T> int EEPROM_readAnything(int ee, T& value)
+{
+    byte* p = (byte*)(void*)&value;
+    unsigned int i;
+    EEPROM.begin(sizeof(value));
+    for (i = 0; i < sizeof(value); i++)
+          *p++ = EEPROM.read(ee++);
+    EEPROM.end();
+    return i;
+}

code/oakpowerboard/oakpowerboard.ino

@@ -9,23 +9,33 @@
 #include "font/roboto_thin_20.h"
 #include "images.h"
 
+#include <EEPROM.h>
+
+#include "eepromanything.h"
+
 #define PULSES_PER_KWH 375
 #define WH_PER_PULSE (1000.0F / PULSES_PER_KWH)
 
+struct config_t
+{
+  int state;
+  float consumption_total;
+  int pulse_count_current_kwh;
+} storage;
+
 #define BTN_1 9
 #define BTN_2 8
 #define BTN_3 7
 #define BTN_4 6
 #define PULSE_PIN 5
 #define DEBUG_LED 10
 
-int pulse_count_current_kwh;
+#define EEPROM_READ_ADDR 0
 
-float consumption_total = 56712.0f;
-char consumption_total_str[10] = "56712.00";
+char consumption_total_str[10] = "00000.00";
 
 float consumption_current = 0.0F;
-char consumption_current_str[6] = "00000";
+char consumption_current_str[6] = "Wait";
 
 long time_since_last_pulse = millis();
 
@@ -80,6 +90,15 @@ void trigger_pulse() {
 }
 
 void setup() {
+  EEPROM_readAnything(EEPROM_READ_ADDR, storage);
+  if(storage.state != 0xF7) {
+    storage.state = 0xF7;
+    storage.consumption_total = 56712.0f;
+    storage.pulse_count_current_kwh = 0;
+    EEPROM_writeAnything(EEPROM_READ_ADDR, storage);
+  }
+  dtostrf(storage.consumption_total, 6, 2, consumption_total_str);
+
   ui.setTargetFPS(30);
   ui.setActiveSymbole(activeSymbole);
   ui.setInactiveSymbole(inactiveSymbole);
@@ -115,8 +134,6 @@ void setup() {
   attachInterrupt(digitalPinToInterrupt(BTN_4), toggle_b4, FALLING);
 }
 
-bool btn_state = false;
-
 void loop() {
   int remainingTimeBudget = ui.update();
   long deadline = millis() + remainingTimeBudget;
@@ -144,13 +161,14 @@ void loop() {
     }
 
     if(pulse_triggered == true) {
-        pulse_count_current_kwh++;
-        if(pulse_count_current_kwh == PULSES_PER_KWH) {
-          consumption_total++;
-          pulse_count_current_kwh = 0;
+        storage.pulse_count_current_kwh++;
+        if(storage.pulse_count_current_kwh == PULSES_PER_KWH) {
+          storage.consumption_total++;
+          storage.pulse_count_current_kwh = 0;
+          EEPROM_writeAnything(EEPROM_READ_ADDR, storage);
         }
         consumption_current = get_consumption_from_time_since_last_pulse(time_since_last_pulse);
-        dtostrf(consumption_total + ((((float)pulse_count_current_kwh) * WH_PER_PULSE) / 1000.0F), 6, 2, consumption_total_str);
+        dtostrf(storage.consumption_total + ((((float)storage.pulse_count_current_kwh) * WH_PER_PULSE) / 1000.0F), 6, 2, consumption_total_str);
         dtostrf(consumption_current, 4, 0, consumption_current_str);
         time_since_last_pulse = millis();
         pulse_triggered = false;