ESP32 Forum

Posted: **Wed Jan 20, 2021 3:16 pm**

Hey there,

I don't know why, but I can't wake up the SOC (pico D4) from deep sleep by the ULP Coprocessor. The ULP code is running correctly, incrementing a variable that I can successfully read out when waking the SOC by the timer. Code is simple:

Code: Select all

static void init_ulp_program(void) {
    ulp_x = 0;
    ESP_ERROR_CHECK( ulp_load_binary(0, ulp_main_bin_start, (ulp_main_bin_end - ulp_main_bin_start) / sizeof(uint32_t)) ); // load binary into rtc
    ESP_ERROR_CHECK( ulp_set_wakeup_period(0, 2000*1000) ); // run every 2 seconds
    ESP_ERROR_CHECK( ulp_run((&ulp_entry - RTC_SLOW_MEM) / sizeof(uint32_t)));
}

extern "C" void app_main() {
    while(1) {
        if(firstStart) {
            firstStart = false;
            init_ulp_program();
        }
        printf("X = %d\n", ulp_x & UINT16_MAX);

        ESP_ERROR_CHECK( esp_sleep_enable_ulp_wakeup() );
        esp_deep_sleep_start(); 
    }
}

And the ULP code:

Code: Select all

#include "soc/rtc_cntl_reg.h"
#include "soc/soc_ulp.h"
#include "soc/rtc_io_reg.h"

	.bss

	.global x
x:	.long 0

	.text
	.global entry
entry:
	move r1, x    // Get adress of x
	ld r0, r1, 0  // Read x in r0
	add r0, r0, 1 // Increment x
	st r0, r1, 0  // Save the x in memory

	wake
	halt

The ULP code is running, but somehow totally ignores the "wake".

Anybody has an idea?

Thanks in advance.

Posted: **Wed Jan 20, 2021 11:19 pm**

Hello @timmbo

your code is actually working and the SoC is woken up by the 'wake' command. You can easily test that by removing the 'wake' command - the SoC stays in deep sleep forever.
Some remarks:
- you don't need a while loop in your main code - when the SoC wakes from deep sleep the code is run from the top again anyhow
- ulp_set_wakeup_period(0, 2000*1000) causes the ULP code to start to run 2 seconds after the SoC goes into deep sleep - that is why the SoC is in deep sleep for about 2 seconds, then woken up again by the 'wake' command
- using esp_sleep_get_wakeup_cause() gives you the wake up reason - reset or ulp or ...
Here is a revised main code:

Code: Select all

void app_main() {
    esp_sleep_wakeup_cause_t cause = esp_sleep_get_wakeup_cause();
    if (cause != ESP_SLEEP_WAKEUP_ULP) {
        printf("Not ULP wakeup, initializing ULP\n");
        init_ulp_program();
    } else {
        printf("ULP wakeup\n");
        printf("X = %d\n", ulp_x & UINT16_MAX);
    }

    ESP_ERROR_CHECK( esp_sleep_enable_ulp_wakeup() );
    esp_deep_sleep_start();
}

Thanks
Felix

Posted: **Sun Jan 24, 2021 8:10 pm**

Hi Felix,

thanks for your answer. My problem was that the SOC did not wake up at all. I found the reason though: I'm using PlatformIO where all compilers and tools were up to date except the ULP compiler. After updating the framework it now works.

Best, Timm

ESP32 Forum

ESP32 ULP can't wake up SOC from deep sleep

ESP32 ULP can't wake up SOC from deep sleep

Re: ESP32 ULP can't wake up SOC from deep sleep

Re: ESP32 ULP can't wake up SOC from deep sleep