From a53e00b216d7b99f9410035df3ddcdae1d72a43f Mon Sep 17 00:00:00 2001
From: Fisch <interfisch@gmx.net>
Date: Thu, 15 Oct 2020 23:13:25 +0200
Subject: [PATCH] add disableABC for mhz19

---
 src/main.cpp | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/src/main.cpp b/src/main.cpp
index f3c5d90..d1241f3 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -106,6 +106,8 @@ struct sensordata
   //SW Serial TX: to mhz19 rx (blue cable)
   //co2 sensor needs 5v
 
+  //if ABC is disabled (see in setup function) sensor should be calibrated manually. leave outdoors (=400ppm) with no direct sunlight for >20min, then connect HD pin to GND for at least 7 seconds.
+
   #include <SoftwareSerial.h>
 
   SoftwareSerial mhz19_swSerial;
@@ -143,6 +145,8 @@ void setup() {
   Serial.println();
   Serial.println("Booting");
 
+  delay(1000); //wait for sensors to get powered
+
   #ifdef SENSOR_DHT22
     Serial.println("initializing dht");
     dht.begin();
@@ -221,6 +225,16 @@ void setup() {
     
     mhz19_swSerial.begin(BAUD_RATE_MHZ19, SWSERIAL_8N1, MHZ19_SERIAL_RX, MHZ19_SERIAL_TX, false, 256);
     mhz19.setSerial(&mhz19_swSerial);
+    
+    uint8_t mhz19abctries=10;
+    while(!mhz19.disableABC() && mhz19abctries>0) { //disable automatic baseline correction (abc does calibration every 24h -> needs to have 400ppm co2 level sometime during that time)
+      delay(500); //wait some time for mhz to be initialized
+      Serial.print("disableABC Failed! try="); Serial.println(mhz19abctries);
+      mhz19abctries--;
+    }
+    if (mhz19abctries>0) {
+      Serial.println("mhz19 abc disabled successfully");
+    }
   #endif