Mutex without FreeRTOS

[michprev]

Hello,
what is the correct way to implement simple mutex to share date between Core 0 (FreeRTOS) and Core 1 (without FreeRTOS)? There is a simple example for ARM: http://infocenter.arm.com/help/index.js ... 03s02.html.

[ESP_igrr]

You can build some form of mutual exclusion on top of the atomic compare-and-set instruction.

Here's the basic C wrapper for it: https://github.com/espressif/esp-idf/bl ... #L273-L290

Xtensa port of FreeRTOS has its spinlocks (portMUX_TYPE) built on top of it: https://github.com/espressif/esp-idf/bl ... ort.c#L302 (the link is to an older version, because the most recent one in master branch is a bit more complicated due to external RAM support).

[michprev]

Is there any option for dual-core mutex? E. g. what happens when both cores access the same peripheral register / memory segment?

[ESP_Sprite]

That is what the spinlock is for. On unicore systems, just disabling the interrupts is enough, but on multicore you need spinlocks.