Boot problem with ESP32-WROOM-32E-N8

[jb-mtd]

Hello,
I have a problem booting from ESP32 (ESP32-WROOM-32E-N8). The ESP is only connected to the most necessary pins. So with:
- 3.3 V (stable voltage, checked with Oszi)
- GND
- EN is connected to 3.3V for flashing
- IO0 is connected to GND for flashing
- RX for flashing
- TX for flashing

The flashing works. After flashing the boot process runs as an endless loop with the following messages:
9:44:33.227 -> ets Jul 29 2019 12:21:46
9:44:33.227 ->
9:44:33.227 -> rst:0x1 (POWERON_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
9:44:33.227 -> configsi��ets Jul 29 2019 12:21:46
.... LOOP .....

The program runs on an ESP-32 Dev Kit C V4 without any problems.
Do I need to assign more pins - or what am I doing wrong?
Thanks for your help!
Juergen

[ESP_Sprite]

What power supply are you using? This very much looks like a brownout early in the booting process.

[jb-mtd]

The power supply comes from the USB programming unit. Only the power supply for the ESP is needed - no external control. With the Oszi I could not detect a voltage drop.

Do I have to control / assign other pins or are the 6 contacts enough for the ESP to run cleanly?

Thanks for more ideas and hints!

[jb-mtd]

Hello,
I have installed a capacitor with 10µF at the 3.3V power supply - unfortunately without the behavior has changed. For me it would be important to know if I have to control or connect other than the used IO ports. If not, I can ignore it for further troubleshooting.
Thanks a lot, Jürgen

[ESP_Sprite]

The power supply comes from the USB programming unit. Only the power supply for the ESP is needed - no external control. With the Oszi I could not detect a voltage drop.

And what is that power supply based on? If it's a poor FT232 running the show on its internal LDO, for instance, that's going to be woefully underpowered. I'd suggest you try to power the ESP from a known-good 3.3V power supply (like a lab power supply) first, see if that makes the problem go away. As the datasheet says, you want something that can output >=500mA otherwise you may run into brown-out issues.

[jb-mtd]

Hello,
have connected a lab power supply as voltage source - unfortunately there was no change. I am still grateful for any hints.

Again my question: do I have to connect other pins than the 6 lines or should it work like this?

When booting, the pinout looks like this:
- 3.3 V (stable voltage, checked with Oszi, at lab power supply)
- GND
- EN not used - there is a Pull-UP
- IO0 not used
- RX for serial communication
- TX for serial communication

Thanks a lot, Jürgen

[jb-mtd]

Hello,
enclosed is some more information about the current setup:
- I have only one GND contact connected
- pin IO12 is not connected, like all other IOs

Best Regards, Jürgen

[ESP_Sprite]

I'd think your connections are indeed suspect; if anything, having EN forced high is not something we support as the ESP does need a power-on reset. I'd suggest you go through the datasheet and hardware reference guidelines and hook everything up as indicated there: a RC network on EN, bootstrap pins connected to the proper pullups/pulldowns where needed.

[jb-mtd]

Hello,
OK I have connected the RC network (10k, 0.1µ) to EN. Do I have to connect more ports? Please can you give me an answer on this.

I now get the following messages when programming:
--------------------------
Compilation complete.
esptool.py v3.0-dev
Serial port COM6
Connecting.....
Chip is ESP32-D0WDQ6 (revision 1)
Features: WiFi, BT, Dual Core, 240MHz, VRef calibration in efuse, Coding Scheme None
Crystal is 40MHz
MAC: 40:91:51:be:f0:00
Uploading stub...
Running stub...
Stub running...
Changing baud rate to 921600
Changed.
Configuring flash size...
Warning: Could not auto-detect flash size (FlashID=0x0, SizeID=0x0), defaulting to 4MB
Compressed 8192 bytes to 47...
Writing at 0x0000e000... (100 %)
Wrote 8192 bytes (47 compressed) at 0x0000e000 in 0.0 seconds (effective 2730.7 kbit/s)...

A fatal error occurred: Timed out waiting for packet header
Upload error: Failed uploading: uploading error: exit status 2

-----------
And the following message when booting:
10:6:22.958 -> rst:0x10 (RTCWDT_RTC_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
10:6:22.958 -> flash read err, 1000
10:6:22.958 -> ets_main.c 371
10:6:23.284 -> ets Jun 8 2016 00:22:57

There seems to be something wrong with on the ESP? How do you see it?

Thanks, Juergen

[ESP_Sprite]

Yes, that means it can't talk to the flash, which is odd because that is internal to the module and doesn't have any connections to the outside. Do you happen to have anything connected to GPIO12? That affects the flash voltage; that's just about the only thing I can imagine could have an effect.