Unable to connect to EPS32

[GeoESP32]

Bought 4 ESP-WROOM-32 boards and tested them with Blink sketch. The first one was passed but the others fail. I got an error message below:

Connecting........_____....._____....._____....._____....._____....._____....._____....._____....._____.....____An error occurred while uploading the sketch
_
A fatal error occurred: Failed to connect to ESP32: Timed out waiting for packet header

Are they defective and should be returned?

[kolban]

If it were me, I'd pick one of the boards that doesn't appear to be working. I'd then reboot my PC ... I'd then list the serial / USB devices attached and then attach the ESP32. I'd validate that a new board/device appears. Finally I'd try connecting to it and see if it works.

[mikemoy]

If what Kolban says does not work, and your sure you have the right com port. Try sticking a 0.1uf -0.22uf from pin 3 (EN) to gnd.

[GeoESP32]

Thank you, kolban and miemoy, for the replies.

Followed both suggestions. Still no go. I exchanged two boards, good and bad, on the same computer with the same sketch. The good one is still good but the bad one is no good. I checked the board info for each and both show up, no issue. In the Device Manager, the port I selected is marked "Silicon Labs CP210x USB to UART Bridge (COMxx.) It is the only one for both boards.

If no other suggestions available, I'll return it back to the dealer. Sigh...

[kolban]

Next thing to try is attaching a serial monitor (eg. putty) to the boards at 115200 baud. Boot the board with the reset/EN button and see what (if any) messages are logged in the case of the "good" board and the "bad" board. Make sure you use the same USB cable in both cases.

[GeoESP32]

Thank you, kolban, for continuing the discussion.

I somehow got the "bad" board working with WiFiScan sketch even tho' I got the same error message while uploading. However, it will not work with Blink sketch.

With the serial monitor attached via USB, I got the info for both "good" and "bad" boards when EN button is pressed.


"Good" board outputs:

ets Jun 8 2016 00:22:57

rst:0x1 (POWERON_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
flash read err, 1000
ets_main.c 371
ets Jun 8 2016 00:22:57

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:812
load:0x40078000,len:0
load:0x40078000,len:11572
entry 0x40078a5c


"Bad" board outputs:

ets Jun 8 2016 00:22:57

rst:0x1 (POWERON_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:0x3fff0010,len:4
load:0x3fff0014,len:588
load:0x40078000,len:0
load:0x40078000,len:9768
entry 0x400789b8