ESP8266 Community Forum

- Sun Jan 06, 2019 6:26 pm #79906 Hello everybody,

I've bought this esp-12e module (2 of them). Now I'm trying to establish USB connectivity to them.

I'm using a 3.3V USB-TTL converter and an external power supply 3.3V 0.9mA (with common ground with USB-to-TTL) that works like a charm with development boards including esptool.py operation and wifi transmission. I also verified that the converter with short-circuited 3.3V-VCC and RX-TX gives me back my input in Arduino IDE serial monitor.

My connections are like here: .

When using `miniterm.py /dev/ttyUSB0 74880`, I have something like:

Code: Select all ets Jan  8 2013,rst cause:2, boot mode:(3,0)

ets_main.c


or else, if pressing GPIO0 upon reboot:

Code: Select all ets Jan  8 2013,rst cause:2, boot mode:(1,6)


But I do not get anything after the last `ets_main.c`, no new wi-fi networks around either. I do not get anything readable as well when using 9600, 57600, 115200 baud rates.

After disconnecting miniterm.py (and possibly replugging usb and power to esp) I'm trying to issue `esptool.py -p /dev/ttyUSB0 read_mac`, but to no avail:

Code: Select allesptool.py v2.5.1
Serial port /dev/ttyUSB0
Connecting........_____....._____....._____....._____....._____....._____....._____

A fatal error occurred: Failed to connect to Espressif device: Timed out waiting for packet header


Again, no baud rates help: 4800, 9600, 57600, 74880, 115200, 460800.

The result is quite confusing: I can read debug info, thus my connection works, I can read USB loopback thus my converter works, I can (again) read debug info, thus my board works (at least to some extent).

BTW, I replicated this wiring using a devboard and its pin header, and did not succeed as well, so I presume there is something wrong with my schematics. The dev board works great if I use its internal converter.

Does anyone see anything awfully stupid here that ruins the connection? I'm feeling like having read all different pieces of advice available on the Internet, and cannot find anything new helpful.

Thank you in advance.

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Last edited by gluk47 on Tue Jan 08, 2019 9:56 am, edited 1 time in total.

- Mon Jan 07, 2019 8:06 am #79920 the "ets_main.c" is the output of an empty module (no fw flashed) after reset, trying to start any user code.
You aren't able to connect via esptool because you are not in "bootloader" mode.
keep gpio0 connected to gnd during reset (or power on) and then try to connect via esptool...

- Mon Jan 07, 2019 7:48 pm #79925

the "ets_main.c" is the output of an empty module (no fw flashed) after reset, trying to start any user code.
You aren't able to connect via esptool because you are not in "bootloader" mode.
keep gpio0 connected to gnd during reset (or power on) and then try to connect via esptool...

Thank you for the response.
Actually, that's what I've done when got ' ets Jan 8 2013,rst cause:2, boot mode:(1,6)' — note «1» in the boot mode.

I've just tried a fresh boot with GPIO0 connected to ground via 220 Ohm, got 'ets Jan 8 2013,rst cause:2, boot mode:(1,0)' and still no progress.

- Tue Jan 08, 2019 9:56 am #79934 I found that stupid thing.

I have soldered my esp12-e to a breakout board and left its RX pin almost unsoldered. Thus I obviously got output from the board but could not push anything there.

When checking pins with tester, I pushed the board a bit and made it connect to the breakboard pin and hence did not notice the issue. Resoldering fixed the problem, now my chip works like a charm