To give a rough estimate. the delay due to cache reload is about 3 to 4 ms. Is that expected?

@ESP_Sprite
Thank you for your answer with the explanation about the cache being flushed. I indeed think that this is actually impacting my isr.

Any chance, that I can change my isr in such a way that there is no impacted by the cache having been flushed? Did I understand correctly, that when ...

I just observed, that when changing the page in the himem api with esp_himem_unmap and esp_himem_map these two calls influence the timing of an isr which is triggered by a pin level change. What is going on here?

Actually I'd like to understand what is going on and probably someone can shed some ...

Having spent a night fithing with this. Here is the key:
You can not directly access the UART0.fifo.rw_byte on esp32s2 but have to use READ_PERI_REG(UART_FIFO_AHB_REG(0))

Hope this helps

This got introduced here and I do not understand the behaviour:

https://github.com/espressif/esp-idf/commit/368d623e1af2a43a08a5ec1b5983a75b70ca4071

If SPIRAM is available but not for use by malloc this change will make internal ram very tight.

So, I tried to manually setting the number of caches ...

hey mikemoy

well, I don't care if the answers I am getting are rude or not as long as it helps me to get forward...

So, let me rephrase the question as I don't see how the example you linked would help me:

The original question I have:
How can I get the exact timeofday of a pin (gpio interrupt ...

Well this is quite an old question. But I still could not figure out how to do this in a nontrivial way.

I do use the timer to get a timestamp in the isr and assemble the time later by using the timer and gettimeofday function. By subtracting the difference in the timer value from the gettimeofday ...

Just in case somebody is visiting this:

since a few days there is a new function in the wlan api (only esp-idf 4.2 ):

esp_wifi_get_tsf_time

which seems to be made for the task at hand.

I have multiple esp32 which are connected over wlan with an ap also running on a esp32.
I'd like to sync their clock to an accuracy of about 1ms.

There are multiple things which I could imagine that would work:

* use wlan beacons
The question here is if there is access to the beacon event or if ...

How to get the timeofday from an isr?

If I do use gettimeofday from isr it crashes if the application is also executing gettimeofday because the lock is acquired already by the application.

Here is the relevant traceback:
0x40097ba0: invoke_abort at panic.c:?
0x40097f11: abort at ??:?
0x4008685b ...