ESP8266 Community Forum

- Thu Jun 02, 2016 8:58 am #48452 Hey, New to the forum, been browsing for a while now.

Is there a data sheet for the esp8266 [12E] that details the digital pin resistance. I have a project up and running on a arduino UNO, and to get the Sensor to read correctly we need to compensate for the digital pin resistance [Already taken ito account the nodemcu Analogue voltage divider] It would be great to port this over to the NodeMCU.

Project Code for UNO/MEGA: https://www.element14.com/community/com ... er-for-mcu

- Thu Jun 02, 2016 10:34 am #48462 Your question is not clear ...
Do you means the "input" equivalent resistance ? since the specs mentioned 50nA input leakage current, you can assume that at 3.3V / 50nA = 66MOhm.
Otherwise, if you wish to know the maximum output current, it can drive up to 12mA.

- Thu Jun 02, 2016 12:41 pm #48466 I am driving a voltage divider with a digital pin [set as output], the divider resistance is high enough to limit current to a safe level. But the voltage drop across the driving digital pin is big enough to skew the voltage dividers output voltage.

To take this into account, I model the digital pin as a resistor [It is good enough for the task], for a uno this value can be calculated from the voltage-current graph in the data sheet[see attached]. I cant seem to find a data sheet for the esp8266.


I dont know the correct term for the value, lets call it apparent resistance of digital output pins.

Thanks for the reply,
Mike

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- Thu Jun 02, 2016 6:08 pm #48483 According to Espressif ESP datasheet, and the way I understand it, it is mentioned that Minimum Voh is 0.8 * Vio , so 0.8*3.3V=2.64V when the 12mA maximum of output current is provided. (it doesn't mentioned any temperature for this rating).
https://cdn-shop.adafruit.com/product-f ... N_v4.3.pdf