From e9cc1a912a88186965734946b3ece216731b2188 Mon Sep 17 00:00:00 2001 From: maccoylton Date: Thu, 14 Nov 2019 23:42:51 +0000 Subject: [PATCH] Update README.md --- README.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/README.md b/README.md index 46ea204..983fd78 100644 --- a/README.md +++ b/README.md @@ -21,7 +21,7 @@ sulphur_dioxide (E 220) density PM25 density -The anlaogue output of the MQ135 is connected to the anlog input of you ESP module. If you are using a nodeMCU or Weemos D1 these have a built in voltage divider on the analogue input which scales 3.3v to 1v, so you need to connect a 180k resistor inline betwen the sensor and the anlogue input pin to allow this to scale From 5v to 1v. If you are connecting directly to a bare ESP8266 chip, then you need to add a voltage divider between the sensor and the analog input to scale form 5v to 1v. +The anlaogue output of the MQ135 is connected to the anlog input of you ESP module. If you are using a nodeMCU or Weemos D1 these have a built in voltage divider on the analogue input which scales 3.3v to 1v, so you need to connect a 180k resistor ( think I actualy used 140k) inline betwen the sensor and the anlogue input pin to allow this to scale from 5v. If you are connecting directly to a bare ESP8266 chip, then you need to add a voltage divider between the sensor and the analog input to scale form 5v to 1v. The DHT22 temperature sensor is connected to GPIO5