ESP32 Forum

Hi everybody,

I have the necessity to isolate some GPIO (not RTC) like GPIO16, GPIO18, GPIO22 and GPIO23 during deepsleep in ESP32-WROOM32D module.

In my case GPIO22 and GPIO23 are outputs and using I'm able to fix their status during deep-sleep and wakeup stub.


GPIO16 and GPIO18 are used for I2C bus and have external pull-up resistors. Before entring in deep-sleep should I change them to output mode, set high level and hold their status? Or they are automatically isolated from the external resistors?

Hi, davdav
You do not need to reconfigure the GPIO mode before entering deep-sleep. When `gpio_deep_sleep_hold_en` is called, all digital GPIOs will remain in their current state. But after the chip wakes up from deep sleep and calls `gpio_deep_sleep_hold_dis`, all digital GPIOs will be reset to the default mode. In this case, you need to reconfigure the GPIO before this function call.

thanks !!

ESP_houwenxiang wrote: ↑

Wed Jun 12, 2019 2:10 am

Hi, davdav
You do not need to reconfigure the GPIO mode before entering deep-sleep. When `gpio_deep_sleep_hold_en` is called, all digital GPIOs will remain in their current state. But after the chip wakes up from deep sleep and calls `gpio_deep_sleep_hold_dis`, all digital GPIOs will be reset to the default mode. In this case, you need to reconfigure the GPIO before this function call.

thanks !!

Thank you @ESP_houwenxiang,

In practice, if device wakes-up and I DON'T call `gpio_deep_sleep_hold_dis`, digital GPIO (not RTC) inputs should work as before entering in deep-sleep, right? I.e. in my particular case GPIO16 and GPIO18 will still work as I2C bus. Consider that at every start-up (not regarding if it is a wake up from or a power-on) I init the I2C driver.

However, I will do some test in order to understand how it works, because documentation in my opininon is not so clear regarding the "hold" functionality.

thanks

Yes, all states will remain in the state before sleep. the GPIO can not input or output as you wanted. so, `gpio_deep_sleep_hold_dis` should be called if you want I2C bus works.

Hey davdav and ESP_houwenxiang

Thanks for posting details.

I have exactly the same problem, I believe. Did you get this working?

Here's my setup:
I have three non-RTC GPIO pins (16, 17, 18), and I want them to stay HIGH during deep sleep.

I'm using Arduino IDE:
```
// Stop doing PWM.
ledcDetachPin(16);
pinMode(16,OUTPUT);
digitalWrite(16, HIGH);

ledcDetachPin(17);
pinMode(17,OUTPUT);
digitalWrite(17, HIGH);

ledcDetachPin(18);
pinMode(18,OUTPUT);
digitalWrite(18, HIGH);

gpio_hold_en((gpio_num_t) 16);
gpio_hold_en((gpio_num_t) 17);
gpio_hold_en((gpio_num_t) 18);
gpio_deep_sleep_hold_en();
delay(10000);
esp_deep_sleep_start();
```

Problem:
Pin 16 and 17 go to LOW as soon as I call `esp_deep_sleep_start()`. They should stay HIGH.

Did your IDF code work?

I've read a number of other posts about this topic, and I'm not sure what the problem is.

Would really appreciate any help or hints anyone can give.

Thanks,
Andrew