ESP32 Forum

Posted: **Sun Oct 10, 2021 6:08 pm**

I'm confused by what should be passed in the argument for

ulp_run

I've seen examples that show this:

Code: Select all

ulp_run((&ulp_entry - RTC_SLOW_MEM)/4);

and this

Code: Select all

ulp_run(&ulp_entry - RTC_SLOW_MEM);

In the docs it does say that it should be expressed in 32 bit words - which I think is where the /4 is coming from in other examples.

Which is correct? Or doesn't it matter?

Posted: **Mon Oct 11, 2021 4:50 pm**

&ulp_entry and RTC_SLOW_MEM are both pointers to uint32_t, so the pointer arithmetic will take care of it.
eg. ((uint32_t*) 0x50000004) - ((uint32_t*) 0x50000000) = 1
Maybe in those other examples, &entry is uint8_t*?

As far as I know, the ULP program will always be built such that ulp_entry is at 0x50000000 (ie offset 0), so in practice it doesn't matter still gets the right result.

ESP32 Forum

Correct argument for ulp_run

Correct argument for ulp_run

Re: Correct argument for ulp_run