Hi,
I’m struggling to get the NodeMCU (AZ-Delivery ESP8266mod F-12) working correctly with a NTC showing the correct temperature.
For that reason I wanted to know Explain NodeMCU GPIO voltage if the voltage tolerance would be an issue.
The temperature reading from the ESP is about 4.3 degrees to high. My study is 22 degrees C and HA is measuring 26.1 degrees C and slowly climbing.
I have connected as follows:
According to NTC Sensor — ESPHome. To prevent self heating, the voltage divider is turned on every 60s by a GPIO output
- platform: ntc
sensor: resistance_sensor
name: $upper_devicename Temperature
calibration:
b_constant: 3950
reference_temperature: 25°C
reference_resistance: 10kOhm
- platform: resistance
id: resistance_sensor
sensor: source_sensor
configuration: DOWNSTREAM
resistor: 10kOhm
name: Resistance Sensor
- platform: adc
pin: A0
id: source_sensor
# Added:
update_interval: never
filters:
- multiply: 3.3
interval:
- interval: 60s
then:
- switch.turn_on: ntc_vcc
- component.update: source_sensor
- switch.turn_off: ntc_vcc
- logger.log: "Measure Temp"
- platform: gpio
pin:
number: GPIO5 #GPIO16 # Pin D0
inverted: false
id: ntc_vcc
Logging output:
22:15:47][D][switch:055]: 'ntc_vcc': Sending state ON
[22:15:47][D][sensor:109]: 'source_sensor': Sending state 1.60811 V with 2 decimals of accuracy
[22:15:48][D][resistance:039]: 'Resistance Sensor' - Resistance 9504.8Ω
[22:15:48][D][sensor:109]: 'Resistance Sensor': Sending state 9504.76172 Ω with 1 decimals of accuracy
[22:15:48][D][ntc:026]: 'Irrigation Controller Temperature' - Temperature: 26.1°C
[22:15:48][D][sensor:109]: 'Irrigation Controller Temperature': Sending state 26.14746 °C with 1 decimals of accuracy
[22:15:48][D][switch:016]: 'ntc_vcc' Turning OFF.
[22:15:48][D][switch:055]: 'ntc_vcc': Sending state OFF
[22:15:48][D][main:167]: Measure Temp
I’ve tried to understand the calculation at NTC Thermistor Resistance Calculator V2.0 and the resistance should be 11441Ohm. I found similar threads here 10k NTC Thermistor - Not Reading Resistance Properly? - #7 by ideal2545 and try to learn from there.
I hope some can explain me how to get correct the measurement.
thx for reading.