ESP8266 Community Forum

- Thu Dec 04, 2014 4:49 pm #3997 Hi all,
I want to use the external RST pin of the ESP03 and ESP01 modules from an other digital circuit. The issue is that the external CMOS circuit can't sink a lot of current: max 10mA.
So I took some current measurement recently on the RST pin and I got this face:

Just pulling down to GND the RST pin with a pushbutton caused 45mA flowing through the wires!!!!!!
I tried to pull it low with a 100Ohm, the voltage dropped only to 2.45V. (my power supply is 3V)
So after a short calculation I got 34 Ohms as an internal pull-up resistance value at RST pin.
This looks realy strong pull-up!!!!

I am still affraid that the RST pin will kill my other electronics
Do you have any suggestions? Or did you experience the same?

My alternative ideas to solve the problem:
- Use CH_PD input as a RESET with a pullup resistor. Any issues, experiences on this? Will the device boot up the same?
- Use a MOSFET transistor just to pull to 0 the RST pin - this would be costly, and many external circuit just for this. :S any oppinion??

Thanks for your advice or sharing your experience!!

- Thu Dec 04, 2014 5:16 pm #4003

Use CH_PD input as a RESET with a pullup resistor. Any issues, experiences on this? Will the device boot up the same?

Generally, I saw misbehavior when try to restart chip with Reset pin.
Now I use a switch with 10k pull-up resistor and 100nF capacitor connected to GND.

switch.jpg

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- Fri Dec 05, 2014 3:58 am #4034 Thanks ucy74,
I am going to try it.

What do you think: If I drive the CH_PD from an other circuit, is the capacitor still recommended?

sztomi

- Fri Dec 05, 2014 2:50 pm #4070

If I drive the CH_PD from an other circuit, is the capacitor still recommended?

In general capacitor is for debonce purpose.
Not nedded if You drive CH_PD pin by the logic levels without noise...