disable core 1 for saving power?

[cyberman54]

Is it possible to pin all tasks to core 0 and switch off core 1 to save power?

[ESP_igrr]

Yes, you can choose "Run FreeRTOS on first core only" option in menuconfig, Component config > FreeRTOS menu and build the application again. That will disable 2nd CPU and all the tasks will run on the 1st.

[cyberman54]

Thank you for your reply!
So it is possible, good to know.

But i am not using the ESP-IDF, i am using PlatformIO extension with MS Visual Studio Code. And i'm using framework Arduino for ESP32, because i need a library which has not been ported for ESP32.

Does anyone know where i can find / set the UNICORE compile option on PlatformIO IDE?

[cyberman54]

I found out how to set the single core option from platformIO IDE, someone gave me the hint that this can be done with a build option:

Code: Select all

build_flags = -D  CONFIG_FREERTOS_UNICORE

I tried it and compiled my code with this build option. It has no impact on the power consumption, not 1 mA. So i think the CPU is still running both cores.

How can i check this?

[WiFive]

Arduino and platformio are using precompiled libs so adding that compiler option won't do anything since libesp32.a is already compiled.

[cyberman54]

Thanks for this explanation, now i understand why my change has no impact.

Which Arduino libraries fpr ESP32 should i recompile with the UNICORE build-option to get a single core cpu?

[dizcza]

Is it possible to disable the second core at runtime?

I have a flag in a header file that, if set, uses ULP instead of the second core.

Code: Select all

#define ULP_ENABLE 1

#if ULP_ENABLE
// start ULP and disable core APP_CPU_NUM
#else
// use APP_CPU_NUM to perform the same task
#endif

I could perhaps issue a deep sleep on the second core (can I?) and never wake up if this flag is set, I'm not sure. Either way, deep sleep != power down, not even hibernation.

[lbernstone]

The Tasmota group regularly releases framework sets for the solo chips on platformio.
https://github.com/tasmota/platform-espressif32

[doragasu]

Yes, you can choose "Run FreeRTOS on first core only" option in menuconfig, Component config > FreeRTOS menu and build the application again. That will disable 2nd CPU and all the tasks will run on the 1st.

Does this really disable the second core? Or will it be active but idling? I have an app running on an esp32-s3 and I'm measuring power consumption using a Power Profiler Kit II. Lowering CPU freq to 80 MHz I see a reduction in power consumption of about 4 or 5 mA, but enabling this option I see no noticeable difference. How much reduction should I expect assuming the core was previously active but idle?