ESP8266 Community Forum

- Wed Jun 22, 2016 8:35 am #49596 I been working on reading a tmp36 well it reads it fine but the value is off. I'm reading 223 with my dvm and the adc is returning 240. I'm using a divider with total of 3.2 k trimmed to give a 0 to 1 volt to the adc.

- Wed Jun 22, 2016 8:44 am #49597 I suppose that what you are saying is that the DMM read = 223mV and ADC read = 240mV?
What's the formula that you are using to transform ADC readings in mV?

Check your voltage divider.
Check your VCC value.
Establish ADC input interval.
Recalibate based on Voltage divider and VCC values.

Reply with the results.

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- Wed Jun 22, 2016 9:13 am #49599 Like I said the divider is dead on 1 volt My dvm is reading 223 Yes that's mV. My bag I should of made that clearer. You take the 1000 /1024 = .9765 240 x .9765 = 234.3 mV

- Wed Jun 22, 2016 10:19 am #49604 How is the voltage divider dead? Please explain a bit. What is your voltage divider ratio and how did you calculate it?
You know that depending on your VCC your ADC max input voltage is actually about 0.978V, or even less?
Take a look also here: ESP8266 Internal ADC

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