From fb41466cb7b6341930b7bbeac375a09f4308430d Mon Sep 17 00:00:00 2001
From: Theo Arends <mhtarends@gmail.com>
Date: Mon, 9 Jul 2018 14:18:26 +0200
Subject: [PATCH] Change DS18B20 driver

Change DS18B20 driver to provide better instant results
---
 sonoff/_releasenotes.ino   |  1 +
 sonoff/xsns_05_ds18b20.ino | 73 ++++++++++++++++----------------------
 2 files changed, 32 insertions(+), 42 deletions(-)

diff --git a/sonoff/_releasenotes.ino b/sonoff/_releasenotes.ino
index 6fd301922..65bde0745 100644
--- a/sonoff/_releasenotes.ino
+++ b/sonoff/_releasenotes.ino
@@ -1,4 +1,5 @@
 /* 6.1.0a
+ * Change DS18B20 driver to provide instant results
  * Remove TSL2561 debug message and update library (#2415)
  * Change SHT1x sensor initialization from pre-teleperiod to once during restart to fix I2C interference
  * Add wifi and mqtt status led blinkyblinky to be disabled by SetOption31 1. Does not work when LedPower is On (deliberate) (#871, #2230, #3114, #3155)
diff --git a/sonoff/xsns_05_ds18b20.ino b/sonoff/xsns_05_ds18b20.ino
index dabaf25d4..12ebe3be2 100644
--- a/sonoff/xsns_05_ds18b20.ino
+++ b/sonoff/xsns_05_ds18b20.ino
@@ -26,9 +26,12 @@
 #define W1_CONVERT_TEMP      0x44
 #define W1_READ_SCRATCHPAD   0xBE
 
-float ds18b20_last_temperature = 0;
+#define DS18B20_MAX_MISS     5
+
+float ds18b20_temperature = 0;
 uint16_t ds18b20_last_result = 0;
 uint8_t ds18x20_pin = 0;
+uint8_t ds18b20_second = 0;
 
 /*********************************************************************************************\
  * Embedded stripped and tuned OneWire library
@@ -126,12 +129,7 @@ boolean OneWireCrc8(uint8_t *addr)
 
 /********************************************************************************************/
 
-void Ds18x20Init()
-{
-  ds18x20_pin = pin[GPIO_DSB];
-}
-
-void Ds18x20Convert()
+void Ds18b20Convert()
 {
   OneWireReset();
   OneWireWrite(W1_SKIP_ROM);           // Address all Sensors on Bus
@@ -139,25 +137,16 @@ void Ds18x20Convert()
 //  delay(750);                          // 750ms should be enough for 12bit conv
 }
 
-boolean Ds18b20Read(float &t)
+void Ds18b20Read()
 {
   uint8_t data[9];
   int8_t sign = 1;
 
-  if (!ds18b20_last_temperature) {
-    t = NAN;
-  } else {
-    ds18b20_last_result++;
-    if (ds18b20_last_result > 4) {     // Reset after 4 misses
-      ds18b20_last_temperature = NAN;
-    }
-    t = ds18b20_last_temperature;
-  }
-
+  if (ds18b20_last_result) { ds18b20_last_result--; }
 /*
-  if (!OneWireReadBit()) {             //check measurement end
+  if (!OneWireReadBit()) {     // Check end of measurement
     AddLog_P(LOG_LEVEL_DEBUG, PSTR(D_LOG_DSB D_SENSOR_BUSY));
-    return !isnan(t);
+    return;
   }
 */
   for (uint8_t retry = 0; retry < 3; retry++) {
@@ -173,36 +162,40 @@ boolean Ds18b20Read(float &t)
         temp12 = (~temp12) +1;
         sign = -1;
       }
-      t = ConvertTemp(sign * temp12 * 0.0625);
-      ds18b20_last_result = 0;
-    }
-    if (!isnan(t)) {
-      ds18b20_last_temperature = t;
-      return true;
+      ds18b20_temperature = ConvertTemp(sign * temp12 * 0.0625);
+      ds18b20_last_result = DS18B20_MAX_MISS;
+      return;
     }
   }
   AddLog_P(LOG_LEVEL_DEBUG, PSTR(D_LOG_DSB D_SENSOR_CRC_ERROR));
-  return !isnan(t);
+}
+
+/********************************************************************************************/
+
+void Ds18b20EverySecond()
+{
+  ds18x20_pin = pin[GPIO_DSB];
+  ds18b20_second++;
+  if (ds18b20_second &1) {
+    Ds18b20Convert();          // Start conversion, takes up to one second
+  } else {
+    Ds18b20Read();             // Read temperature
+  }
 }
 
 void Ds18b20Show(boolean json)
 {
-  float t;
-
-  if (Ds18b20Read(t)) {                // Check if read failed
+  if (ds18b20_last_result) {   // Check for valid temperature
     char temperature[10];
 
-    dtostrfd(t, Settings.flag2.temperature_resolution, temperature);
-
+    dtostrfd(ds18b20_temperature, Settings.flag2.temperature_resolution, temperature);
     if(json) {
       snprintf_P(mqtt_data, sizeof(mqtt_data), PSTR("%s,\"DS18B20\":{\"" D_JSON_TEMPERATURE "\":%s}"), mqtt_data, temperature);
 #ifdef USE_DOMOTICZ
-      if (0 == tele_period) DomoticzSensor(DZ_TEMP, temperature);
+      if (0 == tele_period) { DomoticzSensor(DZ_TEMP, temperature); }
 #endif  // USE_DOMOTICZ
 #ifdef USE_KNX
-      if (0 == tele_period) {
-        KnxSensor(KNX_TEMPERATURE, t);
-      }
+      if (0 == tele_period) { KnxSensor(KNX_TEMPERATURE, ds18b20_temperature); }
 #endif  // USE_KNX
 #ifdef USE_WEBSERVER
     } else {
@@ -210,7 +203,6 @@ void Ds18b20Show(boolean json)
 #endif  // USE_WEBSERVER
     }
   }
-  Ds18x20Convert();   // Start conversion, takes up to one second
 }
 
 /*********************************************************************************************\
@@ -225,11 +217,8 @@ boolean Xsns05(byte function)
 
   if (pin[GPIO_DSB] < 99) {
     switch (function) {
-      case FUNC_INIT:
-        Ds18x20Init();
-        break;
-      case FUNC_PREP_BEFORE_TELEPERIOD:
-        Ds18x20Convert();   // Start conversion, takes up to one second
+      case FUNC_EVERY_SECOND:
+        Ds18b20EverySecond();
         break;
       case FUNC_JSON_APPEND:
         Ds18b20Show(1);