ESP32 stops working for no apparent reason in field

[Kalyan]

Hi,

I am using ESP32 Wroom in a product. After a month of operation the devices stops working. We find that the device does not boot. If I try to flash ESP32, I am getting the error following. The devices were purchased from a reputed online vendor.

esptool.py v2.3.1
Connecting........_____....._____....._____....._____....._____....._____....._____....._____....._____....._____
A fatal error occurred: Failed to connect to ESP32: Timed out waiting for packet header

I am flashing from Command prompt with following command.
C:\Project\SLC>"C:\Project\SLC"\esptool.exe --chip esp32 --port com27 --baud 921600 --before default_reset --after hard_reset write_flash -z --flash_mode dio --flash_freq 80m --flash_size detect 0xe000 "C:\Project\SLC"\boot_app0.bin 0x1000 "C:\Project\SLC"\bootloader_qio_80m.bin 0x10000 "C:\Project\SLC"\controller.ino.bin 0x8000 "C:\Project\SLC"\controller.ino.partitions.bin

Replacing ESP32 fixes the problem. I believe its a reliability issue with ESP32, has anybody faced such reliability issues with ESP32 Wroom?

[nevercast]

What is the environment that the device is deployed in? How is it enclosed? Could mositure damage or other harsh conditions be a possibility ?

[ESP_Angus]

Hi Kalyan,

This seems very unusual. Has it happened to more than one device?

As nevercast suggests, this may be possible if physical conditions have damaged the WROOM module in some way.

How are you resetting the WROOM into bootloader mode? If you connect a serial program at 115200bps and look at the serial output from the device while resetting it manually, do you see any output?

[Kalyan]

What is the environment that the device is deployed in? How is it enclosed? Could mositure damage or other harsh conditions be a possibility ?

Hai nevercast,
I am using IP65 box. Box will expose to sunlight. Inside box temperature is up to 55 degree Celsius and no moisture.

[Kalyan]

Hai ESP_Angus,
This has happened to six to nine devices out of 148. At 115200bps I got 3 different results in nine devices.

• In one device it is printing following message continuously.
  rst:0x10 (RTCWDT_RTC_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
  configsip: 0, SPIWP:0xee
  clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00
  mode:DIO, clock div:1
  load:0x3fff0018,len:4
  load:0x3fff001c,len:952
  load:0x40078000,len:6084
  load:0x40080000,len:7936
  csum err:0x37!=0xd7
  ets_main.c 371
  ets Jun 8 2016 00:22:57

• In two devices it is printing following message continuously.
  rst:0x10 (RTCWDT_RTC_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
  flash read err, 1000
  ets_main.c 371
  ets Jun 8 2016 00:22:57

• In 6 devices it is not print anything.

How are you resetting the WROOM into bootloader mode?

Please check below schematic.

[rodmcm]

Looks like a continuous reset. Perhaps a pull up resistor on the Reset line.

[WiFive]

No protection on 12v input?

[Kalyan]

No protection on 12v input?

Hai,
12v input is from SMPS. Which protection is needed?

[Kalyan]

Looks like a continuous reset. Perhaps a pull up resistor on the Reset line.

Hai,

I didn't understand what you are telling, can you please elaborate?

[woofy!]

I would suspect a power supply issue with an unstable 3v3 seeing much higher spikes.
There is no series diode on the input to the regulator. Use a schottky or fast recovery diode.
There is no protection on the 12v. I would use a transzorb or TVS diode across the 12v supply, and include a fuse too.
The 0.01uF input capacitor on its own is useless, use 470uF-680uF as well.