ESP32-S2 reset loop on startup, sometimes it boots

[degesz]

Hello, I'm having a problem with esp32-s2 (specifically the S2-MINI-N4 module)

I have this module on a custom board. when I reset it, it enters a boot reset loop, dumping this into serial:

Code: Select all

rst:0x3 (RTC_SW_SYS_RST),boot:0x1b (SPI_FAST_FLASH_BOOT)
Saved PC:0x400512fe
SPIWP:0xee
mode:DIO, clock div:1
load:0x3ffe6100,len:0x524
load:0x4004c000,len:0xa70
load:0x40050000,len:0x2958
entry 0x4004c18c
ESP-ROM:esp32s2-rc4-20191025
Build:Oct 25 2019

Sometimes, after seemingly random amount of reset cycles, it boots and runs my code.

The code is just a LED blink with serial:

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#include <Arduino.h>


const int LED_PIN = 2; // On-board LED is usually GPIO 2

void setup() {
  Serial.begin(115200);           // Start Serial Monitor
  delay(1000);                    // Give time for Serial to open
  Serial.println("ESP32 Blink Test Starting...");

  pinMode(LED_PIN, OUTPUT);
}

void loop() {
  Serial.println("LED ON");
  digitalWrite(LED_PIN, HIGH);
  delay(1000); // Wait 1 second

  Serial.println("LED OFF");
  digitalWrite(LED_PIN, LOW);
  delay(1000); // Wait 1 second
}

My platformio.ini file is this:

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[env:esp32-s2-saola-1]
platform = espressif32
board = esp32-s2-saola-1
framework = arduino
monitor_speed = 115200
monitor_filters = esp32_exception_decoder

Do you know what could be causing this? the same setup worked correctly on a previous revision of my board, so I suspect it might be a hardware problem.
I checked power with oscilloscope, the 3V3 is solid.
Basically all pins are connected to something. Are there any specific pins I should check?

[degesz]

Is it possible that the ESP was damaged in RoHS testing? it was done with XRF spectrometer (X-ray)

[lbernstone]

You should not use the chip pull-up (EN) as the reset for the LCD. Either use a gpio, or tie it to 3v3.

[degesz]

You should not use the chip pull-up (EN) as the reset for the LCD. Either use a gpio, or tie it to 3v3.

Yes, I know this isn't the proper way to reset the LCD, the schematic was drawn by someone else.
This doesn't cause the resetting issue though, it was done this way on previous revision and it worked fine

[lbernstone]

Reboots without any backtrace or panic are typically a power issue. That could be a boot timing issue, inadequate capacitance, or just not enough current available from your power supply.