ESP8684 RTC memory

timmbo
Posts: 30
Joined: Fri Jan 03, 2020 11:43 am

ESP8684 RTC memory

Postby timmbo » Sun Nov 27, 2022 8:42 pm

Hi all,

just a quick questions regarding the ESP8684H2: Does the chip have any onboard RTC memory (i.e., can memory be retained after deep sleeps)?

Thanks & Best

ESP_Sprite
Posts: 8921
Joined: Thu Nov 26, 2015 4:08 am

Re: ESP8684 RTC memory

Postby ESP_Sprite » Mon Nov 28, 2022 12:42 am

It doesn't have dedicated memory for this. Closest you could get to this is to store data in main memory and only use light sleep. Alternatively, the ESP8685 (from the ESP32-C3 family) has 8KiB of RTC memory; you could switch to that.

timmbo
Posts: 30
Joined: Fri Jan 03, 2020 11:43 am

Re: ESP8684 RTC memory

Postby timmbo » Mon Nov 28, 2022 7:58 am

Thanks a lot for your answer. This is quite a surprise, making the chip basically not usable for battery operation. Are you sure on that? On

https://products.espressif.com/#/product-comparison

it says the ESP8684 has RTC SRAM of 8 KB?

Best

ESP_Sprite
Posts: 8921
Joined: Thu Nov 26, 2015 4:08 am

Re: ESP8684 RTC memory

Postby ESP_Sprite » Tue Nov 29, 2022 2:33 am

Thanks for noticing that, that's a bug in the product comparison thing. I'll file an issue to have that looked after. The 8684 still is usable for battery operations; you'd have to save any state you'd want to save elsewhere (e.g. in NVS), though. As I mentioned before, if that is not sufficient for your use case, you can always upgrade to the 8685.

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