ULP program: output not working

[perseus086]

I am trying to make blink a led with ULP

It works for some ports but not for others. GPIO 02 works fine 15 too but other no.

Got this code somewhere on the internet.

/*
 * ESP32 Sketch shows that you can program the ulp co-processor using
 * Arduino using the ulp assembly MACRO's. This sketch just blinks the
 * on board LED on for x microseconds and OFF x microseconds using the ulp. 
 * This sketch was inspired from https://github.com/espressif/esp-idf/blob/98e5c475b31ce704e08bd1a48f5d2de3f0b216b0/components/ulp/test/test_ulp.c 
 */
#include "esp32/ulp.h"
#include "driver/rtc_io.h"

void ULP_BLINK_RUN(uint32_t us);

void setup() {
  // microseconds to delay between halt and wake states
  ULP_BLINK_RUN(1000000);
}

void loop() {
  // put your main code here, to run repeatedly:

}
// ------------------------------------------------------------------------
void ULP_BLINK_RUN(uint32_t us) {

  RTC_SLOW_MEM[12] = 0;
  ulp_set_wakeup_period(0, us);
  const ulp_insn_t  ulp_blink[] = {
    I_MOVI(R3, 12),                         // #12 -> R3
    I_LD(R0, R3, 0),                        // R0 = RTC_SLOW_MEM[R3(#12)] 
    M_BL(1, 1),                             // GOTO M_LABEL(1) IF R0 < 1
    I_WR_REG(RTC_GPIO_OUT_REG, 14, 14, 1),  // RTC_GPIO36 = 1---> EXPECTING TO TURN ON LED
    I_SUBI(R0, R0, 1),                      // R0 = R0 - 1, R0 = 1, R0 = 0
    I_ST(R0, R3, 0),                        // RTC_SLOW_MEM[R3(#12)] = R0
    M_BX(2),                                // GOTO M_LABEL(2)
    M_LABEL(1),                             // M_LABEL(1)
      I_WR_REG(RTC_GPIO_OUT_REG, 14, 14, 0),// RTC_GPIO36 = 0  ---> EXPECTING TO TURN OFF LED
      I_ADDI(R0, R0, 1),                    // R0 = R0 + 1, R0 = 0, R0 = 1
      I_ST(R0, R3, 0),                      // RTC_SLOW_MEM[R3(#12)] = R0
    M_LABEL(2),                             // M_LABEL(2)
    I_HALT()                                // HALT COPROCESSOR
  };
  const gpio_num_t led_gpios[] = {
    GPIO_NUM_2,
    GPIO_NUM_0,
    GPIO_NUM_4
  };
  for (size_t i = 0; i < sizeof(led_gpios) / sizeof(led_gpios[0]); ++i) {
    rtc_gpio_init(led_gpios[i]);
    rtc_gpio_set_direction(led_gpios[i], RTC_GPIO_MODE_OUTPUT_ONLY);
    rtc_gpio_set_level(led_gpios[i], 0);
  }
  size_t size = sizeof(ulp_blink) / sizeof(ulp_insn_t);
  ulp_process_macros_and_load(0, ulp_blink, &size);
  ulp_run(0);
}

Here is the code

Anyone knows why it does not work for all the ports?

[Jeroen88]

What pins are not working? Not all pins are free to use. Also GPIO34, 35, 36 and 39 are input only, so these pins will never let you blink a led

[perseus086]

I tried GPIO 0, 2, 4, 15, 13, 12, 25, 26, 32, 33 and others like 36.

Only 0, 2, and 4 working fine. But other pins not.

I found this tweet and I tried with this map: https://twitter.com/i/web/status/1142776900449787904

When I tried with c code for GPIO12. The typical blink example and pin 12 works fine as output:

void setup() {
  // initialize digital pin LED_BUILTIN as an output.
  pinMode(12, OUTPUT);
}

// the loop function runs over and over again forever
void loop() {
  digitalWrite(12, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(1000);                       // wait for a second
  digitalWrite(12, LOW);    // turn the LED off by making the voltage LOW
  delay(1000);                       // wait for a second
}

Maybe it is because I am not initializing the pins as outputs?

[perseus086]

@Jeroen88
I think I get what you tell me. according to: https://www.espressif.com/sites/default/files/1a-esp32_pin_list_en-v0.1.pdf

I can use GPIO 32, 33, 25, 26, 27, 2, 0, 4

Right?

[Jeroen88]

According to this link you should be able to use more pins, maybe dependent on the development board you are using.