Unexpected light sleep and deep sleep behaviour on ESP32-S3

[idea--list]

Board

Adafruit ESP32-S3 Feather

Device Description

Adafruit ESP32-S3 Feather

Hardware Configuration

Nothing attached

Version

latest development Release Candidate (RC-X)

IDE Name

Arduino IDE V1.8.19

Operating System

Windows 10

Flash frequency

80MHz

PSRAM enabled

no

Upload speed

115200

Description

Began to try the ESP32-S3 today and find unexpected behaviour of the native USB-Serial converter.

When the sketch uses deep sleep:
I can hear the sound playing when the COM port detaches and even when the board is recognized when waking up after deep sleep. However the the Serial output updates only before the board goes to deep sleep for the first time. Later on the serial output does not update despite the board is waking up. Power consumption is as expected.
Did not find earlier report regarding deep sleep.

When the sketch uses light sleep:
I do not see any serial output at all (not even in the 1st cycle). Do not hear any sounds for detaching/recognition and also the power consumption drops to the expected level only in the 1st cycle but after that it remains at least 87mA without ever dropping back to low levels. Seem like the board can not reenter light sleep after it has waken up for the first time.
This might be related to #6581

Sketch

#include <WiFiClientSecure.h>

const char* ssid     = "SSID";     // your network SSID (name of wifi network)
const char* password = "password"; // your network password

const char*  server = "www.howsmyssl.com";  // Server URL


WiFiClientSecure client;

void setup() {
  //Initialize serial and wait for port to open:
  Serial.begin(115200);
  delay(15000);

  esp_sleep_enable_timer_wakeup(10e6);  //

  Serial.print("Attempting to connect to SSID: ");
  Serial.println(ssid);
  WiFi.begin(ssid, password);

  // attempt to connect to Wifi network:
  while (WiFi.status() != WL_CONNECTED) {
    Serial.print(".");
    // wait 1 second for re-trying
    delay(1000);
  }

  Serial.print("Connected to ");
  Serial.println(ssid);

  Serial.println("\nStarting connection to server...");
  client.setInsecure();//skip verification
  if (!client.connect(server, 443))
    Serial.println("Connection failed!");
  else {
    Serial.println("Connected to server!");
    // Make a HTTP request:
    client.println("GET https://www.howsmyssl.com/a/check HTTP/1.0");
    client.println("Host: www.howsmyssl.com");
    client.println("Connection: close");
    client.println();

    while (client.connected()) {
      String line = client.readStringUntil('\n');
      if (line == "\r") {
        Serial.println("headers received");
        break;
      }
    }
    // if there are incoming bytes available
    // from the server, read them and print them:
    while (client.available()) {
      char c = client.read();
      Serial.write(c);
    }

    client.stop();

    //esp_deep_sleep_start();
    esp_light_sleep_start();
  }
}

void loop() {
  // do nothing
}

Debug Message

None

Other Steps to Reproduce

No response

I have checked existing issues, online documentation and the Troubleshooting Guide

• I confirm I have checked existing issues, online documentation and Troubleshooting guide.

[idea--list]

Oh, my bad... I am so used to boards that have a dedicated serial to USB converter chip 😉

However the Adafruit ESP32S3 Feather board comes only with the native USB inside the the ESP32S3 module... so when the MCU goes to light/deep sleep the board simply cuts the serial connection to the PC. And it does not reestablish a working serial connection to the PC when the board wakes up.

Is there any solution for that?

[me-no-dev]

Are you using the S3 feather board definition? It should be using TinyUSB (USB-OTG) for serial, which should re-enumerate on boot.

[idea--list]

@me-no-dev
These are the settings i am using:

[idea--list]

By the way meanwhile i also tried putty, but even that behaves exactly the same as Arduino IDE's own serial monitor and the serial connection does not seem to automatically reestablish when the board wakes up from sleep.

However if i close the serial monitor and reopen that again just when the board is waking up, then i see the serial output generated in the actual wake cycle, but as soon the board goes to sleep next time, the serial connection breaks again, and does not reestablish automatically when the board wakes up next time.

[me-no-dev]

Thanks @idea--list . I'll give it a try. Did not expect to have issues with USB-OTG :)

[me-no-dev]

I tested the sketch and it works fine at least on MacOS. I think that you have a small misunderstanding of how light sleep works. As opposed to Deep Sleep, Light Sleep will continue the execution from where esp_light_sleep_start was called. I added print and delay statements to the loop which printed out once light sleep was over.

Some operating systems / USB drivers might not like the fact that the ESP is not responding on the USB while in light sleep and can disable the device/halt it. At least on MacOS that does not seem to be an issue with CDC.

@VojtechBartoska can we get this tested on Linux and Windows?