Use this forum to chat about hardware specific topics for the ESP8266 (peripherals, memory, clocks, JTAG, programming)

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By Greggj
#92894 Hi everyone,

I read the datasheet and cannot find the answer to this question.
I got a device that in order to enter the power saving mode needs one of its pins to be grounded. I've attached it to D1 and
Code: Select alldigitalWrite(D1, LOW);
does bring it successfully down.

However, when the board enters deep sleep, after couple of seconds the level on that pin raises up. The device has internally this input connected high via resistor so it does need an "active" grounding.

Are there any pins on 8266 (or ESP32-S2, as an alternative board for this project) - that stay LOW/HIGH even in deep sleep? Or should I resort to an external transistor to do this job? If so, I'd appreciate suggestions of the external circuitry to achieve that. For instance, I could drive the output high when I want the device to be active. But I don't think 8266 has OpenCollector outputs.

The attached device is a Plantower PMS5003 and the pin in question is PIN3/SET: "Set pin /TTL level@3.3V,high level or suspending is normal working status, while low level is sleeping mode." .