Bunch of fixes

- Remove exponential smoothing because the capacitor is still needed
- Add `livoloShift`
- Add serial debugging
- Add watchdog timer

README.md

@@ -11,10 +11,7 @@ You need to generate the `table.h` for your particular NTC thermistor. It contai
 Measure your NTC resistance at two different temperature points. Then call `table.py` specifying your measurements:
 
 ```sh
-python table.py \
-    --t1 <temperature-1> --r1 <resistance-at-t1> \
-    --t2 <temperature-2> --r2 <resistance-at-t2> \
-    --rf <fixed-resistor>
+python table.py --t1 <temperature-1> --r1 <resistance-at-t1> --t2 <temperature-2> --r2 <resistance-at-t2> --rf <fixed-resistor>
 ```
 
 I recommend to measure your fixed resistor actual resistance to improve accuracy.
@@ -25,13 +22,10 @@ See [Measuring the temperature with NTCs](http://www.giangrandi.ch/electronics/n
 
 ### Note for Livolo thermostats
 
-Livolo's 1-Wire master has non-standard timings and does not read all the data transmitted. You'll need to patch OneWireHub's `OneWireHub_config.h` and `DS18B20.cpp` using the included `livolo.patch`.
+Damn them!
 
-See also https://github.com/orgua/OneWireHub/issues/84.
-
-### Smoothing filter
-
-The code implementes the simplest [exponential smoothing](https://en.wikipedia.org/wiki/Exponential_smoothing) of converted temperature. You may want to adjust `smoothingFactor` according to your needs.
+1. Supposingly, one has to solder out the second sensor deep inside the thermostat **even before turning it on for the first time**. If you've already done that, you may try to figure out the calibrated temperature shift that the thermostat has calculated and remembered. Wait ~4 minutes and note the difference between displayed and real temperatures. Then, change `livoloShift` in the source code to compensate this.
+2. Livolo's 1-Wire master has non-standard timings and does not read all the data transmitted. You'll need to patch OneWireHub's `OneWireHub_config.h` and `DS18B20.cpp` using the included `livolo.patch`. See also https://github.com/orgua/OneWireHub/issues/84.
 
 ### Connections
 

platformio.ini

@@ -12,5 +12,8 @@
 platform = atmelavr
 board = nanoatmega328
 framework = arduino
+upload_port = /dev/cu.wchusbserial*
+monitor_port = /dev/cu.wchusbserial*
+monitor_speed = 2000000
 lib_deps =
     OneWireHub

src/main.cpp

@@ -1,26 +1,33 @@
 #include <Arduino.h>
+#include <avr/wdt.h>
+
 #include <DS18B20.h>
 
 #include "table.h"
 
-// NTC input.
+// NTC input pin.
 constexpr uint8_t adcPin = A1;
 
 // Temperature measurement interval (approximate).
 constexpr unsigned long interval = 1000;
 
 // 1-Wire I/O.
-auto hub = OneWireHub(12); // PB4/MISO
+auto hub = OneWireHub(12); // PB4 aka MISO
 auto ds18b20 = DS18B20(0x28, 0x92, 0x23, 0xC5, 0x1E, 0x19, 0x01); // Copied from a real sensor: 289223C51E190171.
 
-// Exponential smoothing factor.
-constexpr float smoothingFactor = 0.2;
-
-// Error flag indicator.
+// Error LED pin.
 constexpr uint8_t ledPin = 13;
 
+// Livolo thermostat performs some calibration.
+// This is the temperature shift we apply to match the actual temperature.
+constexpr float livoloShift = +3.0f;
+
 void setup() {
-    // TODO: setup WDT.
+    wdt_disable();
+    wdt_enable(WDTO_8S);
+
+    Serial.begin(2000000);
+    while (!Serial);
 
     pinMode(adcPin, INPUT);
 
@@ -38,22 +45,30 @@ float readTemperature(const uint8_t pin) {
 
 void loop() {
     static uint32_t nextMillis = millis();
-    static float temperature = readTemperature(adcPin);
 
-    // TODO: reset WDT before polling the hub.
+    wdt_reset();
     hub.poll();
 
     // Display the error flag. Timeouts are okay.
     const auto error = (uint8_t)hub.getError();
-    digitalWrite(13, ((error != 0) && (error != 3)) ? HIGH : LOW);
+    const auto isError = (error != 0) && (error != 3);
+    digitalWrite(13, isError ? HIGH : LOW);
+    if (isError) {
+        Serial.print("E: ");
+        Serial.println(error);
+    }
 
     if (millis() > nextMillis) {
         // Schedule the next measurement.
         nextMillis = millis() + 1000;
 
-        // Apply basic exponential smoothing filter.
-        // https://en.wikipedia.org/wiki/Exponential_smoothing#Basic_exponential_smoothing
-        temperature = temperature + smoothingFactor * (readTemperature(adcPin) - temperature);
-        ds18b20.setTemperature(temperature);
+        const auto reading = readTemperature(adcPin);
+        ds18b20.setTemperature(reading + livoloShift);
+
+        Serial.print(millis());
+        Serial.print(" ms | ");
+        Serial.print(reading);
+        Serial.println(" °C");
+        Serial.flush();
     }
 }