ESP8266 Community Forum

- Sat Oct 17, 2015 5:56 am #31582 Hi All

I'm using an ESP-07/12 with one of those white adapter plates which has the built in 10k pull up resistor for CH_PD to enable the chip.

If I want to disable the chip can I simply use a stronger pulldown resistor? If so can anyone please suggest a resistor and is this safe to do so for periods of around 1 minute or just really bad practice?

For a bit more info, I'm using the ESP as a WiFi module with an Arduino issuing AT commands. I want to be able to put the ESP to sleep between these commands so I figure I have 2 choices:

1) disable the chip by pulling down CH_PD with an Arduino's GPIO.
2) put the ESP to sleep using AT+GSLP and then trigger the reset pin via the Arduino when I want to wake it up (should I use a pulldown resistor for this?)

Obviously I could remove the pullup resistor from the plate or not use the plate at all for this scenario but I thought I'd ask anyways.

Thanks

- Sat Oct 17, 2015 8:14 am #31586 you should be able to ... Ardunio gpio ---->LEVEL CONVERTER ------> chip_EN
HiZ > 1000 or more resistor should be no problem
Ardunio High enables , Low disables

Chip enables are usually logic level Hi/Lo enables /disables

- Sat Oct 17, 2015 10:50 am #31596

If I want to disable the chip can I simply use a stronger pulldown resistor?

You don't need to add a pulldown (and, in fact, depending on the value that may not even work due to the voltage divider effect). All you need to do is to ground CH_PD (either directly or by applying a logic 0 signal). You can maintain that state for as long as you would like and no damage will ensue. After all, a 10K resistor from 3V3 to ground only conducts 0.33 mA (V divided by R) and only dissipates slightly more than a milliwatt (V squared divided by R).

If the situation involved a pullup rather than a pulldown you would simply connect to Vcc or apply a logic 1 signal. The same current and power considerations apply.

The preceding discussion applies to pins that are inputs as CH_PD is. Pins that are outputs have different considerations.

Don Kinzer
ZBasic Microcontrollers
http://www.zbasic.net

- Tue Oct 20, 2015 11:48 pm #31881 sorry for my late reply, thank you both for your suggestions and information.