hmm, strange, if anything I'd expected the M5Stack Gray to work with low brightness level and the M5Stack Black to not behave due to the fact that the M5Stack Gray has additional hardware (e.g. IMU) consuming power to keep the device powered on.

That said, I suspect the IP5306 switching off due to too light load. Try to add the following statement before going into deep sleep. It should prevent the IP5306 from shutting down under light load.

M5.Power.setPowerBoostKeepOn(true);

Happy Stacking!
Felix

I am afraid you're out of luck. The arduino-esp32 library is based on IDF release 3.3 and the ULP macros for I2C seem to be missing / not implemented yet.

#define OPCODE_I2C 3 /*!< Instruction: read/write I2C (not implemented yet) */

But even with the macros in place it would probably still not work. According to this info it seems that the ULP only allows for two predefined sets of GPIOs to be used for SDA and SDL, none of which are GPIO21/22 used in M5Stack.

Felix

thank you very much. I am happy to hear it works to your liking.

Happy Stacking!
Felix

ULP code and ULP variables share the same area of RTC_SLOW_MEM which is about 8 kB. Right now your ULP variable is reset to 0 at every boot since all of that area is reset to 0 by this command: memset(RTC_SLOW_MEM, 0, 8192);. In addition the ULP code and your ULP variable both are located at the same offset 0 in that area. ulp_process_macros_and_load(0, ulp_prog, &size);

In order to fix this the RTC_SLOW_MEM needs to be orgnanised, e.g. the ULP variables need to be located after (or before) the ULP code and the area used for ULP variables needs to be excluded from being cleared to 0 at every boot.

There are many ways to solve this. In the example I've linked earlier ULP variables are located shortly after the ULP code (offset 36). The solution I've chosen puts the ULP variables into the last of the eight 1 kB blocks of RTC_SLOW_MEM. That leaves more than enough space (the first 7 kB) for ULP code.

Note: Next to the boot count ULP variable I've added a second ULP dummy variable to illustrate how multiple ULP variables could be handled.

Cheers
Felix

#include <M5Stack.h>
#include "esp32/ulp.h"
#include "driver/rtc_io.h"

const int lcdBrightness = 50; // (1-255)

// RTC slow memory map (vars are in the last 1 kB of total 8 kB)
// Note: all ULP commands / vars are 4 bytes in size
const size_t rtc_slow_mem_total_size = 2048; // 8 kB = 4 * 2048
const size_t rtc_slow_mem_vars_space = 256;  // 1 kB = 4 * 256
const size_t rtc_slow_mem_vars_start = rtc_slow_mem_total_size - rtc_slow_mem_vars_space;
const size_t rtc_slow_mem_prog_start = 0;
const size_t rtc_slow_mem_prog_space = rtc_slow_mem_total_size - rtc_slow_mem_vars_space; // 7 kB

const size_t ulp_boot_count_var_offset = 0;
const size_t ulp_dummy_var_offset = 1;

void ulp_start(void) {
  // RTC slow mem init (except space allocated for vars)
  memset(RTC_SLOW_MEM, 0, rtc_slow_mem_prog_space * sizeof(uint32_t));
  // M5Stack LCD backlight is connected to GPIO32 (specify by +14)
  const gpio_num_t lcdPWMPin = GPIO_NUM_32;
  const int lcdPWMBit = RTCIO_GPIO32_CHANNEL + 14;
  // GPIO32 initialization (set to output and initial value is 0)
  rtc_gpio_init(lcdPWMPin);
  rtc_gpio_set_direction(lcdPWMPin, RTC_GPIO_MODE_OUTPUT_ONLY);
  rtc_gpio_set_level(lcdPWMPin, 0);
  // Define ULP program
  const ulp_insn_t ulp_prog[] = {
    M_LABEL(1),
    I_WR_REG(RTC_GPIO_OUT_REG, lcdPWMBit, lcdPWMBit, 1), // on
    I_DELAY(lcdBrightness * 100),
    I_WR_REG(RTC_GPIO_OUT_REG, lcdPWMBit, lcdPWMBit, 0), // off
    I_DELAY(25500),
    M_BX(1),
  };
  // Run ULP program
  size_t size = sizeof(ulp_prog) / sizeof(ulp_insn_t);

  ulp_process_macros_and_load(rtc_slow_mem_prog_start, ulp_prog, &size);
  ulp_run(rtc_slow_mem_prog_start);
}

void setup() {
  M5.begin(true, false, true, false);
  M5.Power.begin();
  M5.Lcd.println("Put something onto the LCD...");

  if(esp_sleep_get_wakeup_cause() == ESP_SLEEP_WAKEUP_TIMER)
  {
    M5.Lcd.println("Woken from timer");
    RTC_SLOW_MEM[rtc_slow_mem_vars_start + ulp_boot_count_var_offset]++;
  }
  else
  {
    M5.Lcd.println("Woken after reset");
    RTC_SLOW_MEM[rtc_slow_mem_vars_start + ulp_boot_count_var_offset] = 0;
    RTC_SLOW_MEM[rtc_slow_mem_vars_start + ulp_dummy_var_offset] = 4711;
  }
  M5.Lcd.println(RTC_SLOW_MEM[rtc_slow_mem_vars_start + ulp_boot_count_var_offset]);
  M5.Lcd.println(RTC_SLOW_MEM[rtc_slow_mem_vars_start + ulp_dummy_var_offset]);

  ulp_start();

  M5.Lcd.println("Going to deep sleep");
  esp_sleep_enable_timer_wakeup(5000);
  esp_sleep_pd_config(ESP_PD_DOMAIN_RTC_PERIPH, ESP_PD_OPTION_ON);
  esp_deep_sleep_start();
}

void loop() {
}

please have a look at the following example which stores variables after the ULP code: deep sleep example

Cheers
Felix

the reason nothing can be seen on the LCD during deep sleep is that the backlight is off. The LCD backlight is driven by GPIO32 (PWM) which is stopped when the ESP32 goes into deep sleep. Luckily GPIO32 can be controlled by the Ultra Low Processor (ULP) too. Below is a small test program which implements PWM for GPIO32 with ULP C macros / assembler.

Cheers
Felix

#include <M5Stack.h>
#include "esp32/ulp.h"
#include "driver/rtc_io.h"

const int lcdBrightness = 1; // (1-255)

void ulp_start(void) {
  // Slow memory initialization
  memset(RTC_SLOW_MEM, 0, 8192);
  // M5Stack LCD backlight is connected to GPIO32 (specify by +14)
  const gpio_num_t lcdPWMPin = GPIO_NUM_32;
  const int lcdPWMBit = RTCIO_GPIO32_CHANNEL + 14;
  // GPIO32 initialization (set to output and initial value is 0)
  rtc_gpio_init(lcdPWMPin);
  rtc_gpio_set_direction(lcdPWMPin, RTC_GPIO_MODE_OUTPUT_ONLY);
  rtc_gpio_set_level(lcdPWMPin, 0);
  // Define ULP program
  const ulp_insn_t  ulp_prog[] = {
    M_LABEL(1),
    I_WR_REG(RTC_GPIO_OUT_REG, lcdPWMBit, lcdPWMBit, 1), // on
    I_DELAY(lcdBrightness * 100),
    I_WR_REG(RTC_GPIO_OUT_REG, lcdPWMBit, lcdPWMBit, 0), // off
    I_DELAY(25500),
    M_BX(1),
  };
  // Run ULP program
  size_t size = sizeof(ulp_prog) / sizeof(ulp_insn_t);
  ulp_process_macros_and_load(0, ulp_prog, &size);
  ulp_run(0);
}

void setup() {
  M5.begin(true, false, true, false);
  M5.Power.begin();
  M5.Lcd.println("Put something onto the LCD...");
  ulp_start();
  M5.Lcd.println("Going to deep sleep");
  esp_sleep_pd_config(ESP_PD_DOMAIN_RTC_PERIPH, ESP_PD_OPTION_ON);
  esp_deep_sleep_start();
}

void loop() {
}

Thank you for your help.
I took the time to try, to test.

For sleep, it's OK.
I made a small example but it doesn't work every time ???

On the other hand, I wish to wake up with the buttons.
I've searched the schematics:
Button A GPIO39
Button B GPIO38
Button C GPIO37

Following the example of this site:
https://randomnerdtutorials.com/esp32-external-wake-up-deep-sleep/

ext0
In this example, the ESP32 wakes up when the GPIO 33 is triggered to high:

esp_sleep_enable_ext0_wakeup(GPIO_NUM_33,1); //1 = High, 0 = Low
Instead of GPIO 33, you can use any other RTC GPIO pin.

#include <M5Stack.h>

#define uS_TO_S_FACTOR 1000000 /* Conversion factor for micro seconds to seconds /
#define TIME_TO_SLEEP 10 / Time ESP32 will go to sleep (in seconds) */
//#define BUTTON_PIN_BITMASK 0x8000000000

void setup()
{
Serial.begin(115200);
M5.begin(true, false, true);
esp_sleep_enable_timer_wakeup(TIME_TO_SLEEP * uS_TO_S_FACTOR);
Serial.println("Setup ESP32 to sleep for every " + String(TIME_TO_SLEEP) + " Seconds");

esp_sleep_enable_ext0_wakeup(GPIO_NUM_39,0); //1 = High, 0 = Low

//esp_deep_sleep_start(); //entre en someil profond

}

void loop() {

M5.update();// update button state

if (M5.BtnA.wasReleased())
{
esp_sleep_enable_ext0_wakeup(GPIO_NUM_39,0); //1 = High, 0 = Low
}

if (M5.BtnB.wasReleased())
{
esp_deep_sleep_start(); //entre en someil profond
}

if (M5.BtnC.wasReleased())
{
M5.Lcd.fillScreen(WHITE);
M5.Lcd.setTextColor(BLUE);
M5.Lcd.setBrightness(100);
M5.Lcd.setTextSize(2);
M5.Lcd.setCursor(40, 60);
M5.Lcd.print("Temperature: ");
}
}

Random Nerd Tutorials published by Rui and Sara Santos have a tutorial how to use the deep sleep mode on the ESP32and how to store data in the RTC memory:

https://randomnerdtutorials.com/esp32-timer-wake-up-deep-sleep/

I havn't tried it out yet, but it probably should also work with the M5Stack ESP32.

@PierreD Tu trouves une code exemplaire de programmation pour le sub-ordnateur ESP32-RTC au site de Rui et Sara Santos à https://randomnerdtutorials.com/esp32-timer-wake-up-deep-sleep/

bonne chance crami25

dernières valeurs et se réveille toutes les X minutes pour mettre à jour les mesures; affichage du nombre d'abonnés twitter, de likes, de visites de pages, etc. Dans tous ces cas d'utilisation, il est utile de laisser le CPU dormir la plupart du temps pendant que l'affichage reste allumé.
Dans tous les cas, ce serait bien si quelqu'un pouvait présenter une solution de travail. Ce n'est probablement que quelques lignes de code, mais je n'arrive pas à trouver les bonnes.

Hello,

I'm editing this old post... Do you have a solution?

Pierre

Thank you.
What some people dont know is that the esp32 is not like an arduino.
the esp32 has 3 cores, 2 primary and 1 Ultra Low power.
In true deep sleep, the primary core are deactivated and the basic "Upkeep" code is off loaded to the ULP.
Because the M5Stack is based on the ESP32 and not much is understood about the ULP, very little progress has been made on deep sleep.
In theory, from what I have read the ULP could maintain a low power screen for a Like (to use your example) and then wake up the core to take the sensor measurements before storing them (for the ulp to recall and display) putting the cores back to sleep.

If you are interested in leaning more, look into the ESP32's ULP (Ultra Low Power core)

In any case, it would be great if someone can present a working solution. It is probably just a few lines of code, but I just can't seem to get the right ones.

I can't believe this problem has no solution: keeping the display of M5stack ON during light or deep sleep. It should be trivial and yet no one on this forum can present a working solution. This seems to be an impossible task!

The reason no solution exist is because having the screen on goes against the purpose of deep sleep and also because it’s such an unusual question that you have asked, no one has yet to think of a solution in the esp32 world.

Please be patient, M5Stack is still a young project and not everything is thought off until the end user posses a query. If you discover a way to do please let us know but in the mean time please continue to wait patiently.