From 0b8408ef134c9569410270dd7e4f9db65c4222c8 Mon Sep 17 00:00:00 2001
From: Achim <achim.haug@airgradient.com>
Date: Thu, 20 Jan 2022 08:26:27 +0700
Subject: [PATCH] improved CO2 code (details
 https://forum.airgradient.com/t/s8-co2-reading-of-1/69/15)

---
 AirGradient.cpp | 54 ++++++++++++++++---------------------------------
 1 file changed, 17 insertions(+), 37 deletions(-)

diff --git a/AirGradient.cpp b/AirGradient.cpp
index cf987e5..d615ac0 100644
--- a/AirGradient.cpp
+++ b/AirGradient.cpp
@@ -607,47 +607,27 @@ const char* AirGradient::getCO2(int retryLimit) {
   return Char_CO2;
 }
 int AirGradient::getCO2_Raw(){
-  int retry = 0;
-    CO2_READ_RESULT result;
-    const byte CO2Command[] = {0xFE, 0X44, 0X00, 0X08, 0X02, 0X9F, 0X25};
-    byte CO2Response[] = {0,0,0,0,0,0,0};
+  const byte CO2Command[] = {0xFE, 0X44, 0X00, 0X08, 0X02, 0X9F, 0X25};
+  byte CO2Response[] = {0,0,0,0,0,0,0};
 
-    while(!(_SoftSerial_CO2->available())) {
-        retry++;
-        // keep sending request until we start to get a response
-        _SoftSerial_CO2->write(CO2Command, 7);
-        delay(50);
-        if (retry > 10) {
-            return -1;
-        }
-    }
-
-    int timeout = 0; 
-    
-    while (_SoftSerial_CO2->available() < 7) {
-        timeout++; 
-        if (timeout > 10) {
-            while(_SoftSerial_CO2->available())  
-            _SoftSerial_CO2->read();
-            break;                    
-        }
-        delay(50);
-    }
+  _SoftSerial_CO2->write(CO2Command, 7);
+  delay(100);  //give the sensor a bit of time to respond
 
+  if (_SoftSerial_CO2->available()){
     for (int i=0; i < 7; i++) {
-        int byte = _SoftSerial_CO2->read();
-        if (byte == -1) {
-            result.success = false;
-            return -1;
-        }
-        CO2Response[i] = byte;
-    }  
-    int valMultiplier = 1;
-    int high = CO2Response[3];                      
-    int low = CO2Response[4];                       
-    unsigned long val = high*256 + low;  
-
+      int byte = _SoftSerial_CO2->read();
+      CO2Response[i] = byte;
+      if (CO2Response[0] != 254) {
+        return -1;  //error code for debugging
+      }
+    }
+    unsigned long val = CO2Response[3]*256 + CO2Response[4];
     return val;
+  }
+  else
+  {
+  return -2; //error code for debugging
+  }
 }
 
 //END CO2 FUNCTIONS //