[SOLVED] unable to get REPL prompt

All ESP8266 boards running MicroPython.
Official boards are the Adafruit Huzzah and Feather boards.
Target audience: MicroPython users with an ESP8266 board.
rpi_nerd
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[SOLVED] unable to get REPL prompt

Post by rpi_nerd » Sat Jul 29, 2017 2:15 pm

I have a WeMos D1 Mini V2 board. I'm able to erase the flash and upload firmware to it, but when I try to access it via serial, I get no repose. The best thing I can get is some garbage when I hit the reset button. This is my second board. The first board that I got about a month ago (same board from the same seller) worked completely fine.



Here's the ebay item listing:
http://www.ebay.com/itm/D1-Mini-V2-Mini ... 2749.l2649

EDIT:I did try it with multiple computers and got the same result. I also tried it with a daily build and also got the same result. I then decided to use it with the Arduino IDE, and serial worked just fine.
Last edited by rpi_nerd on Fri Aug 11, 2017 5:41 pm, edited 1 time in total.

fangis
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Re: unable to get REPL prompt

Post by fangis » Sat Jul 29, 2017 8:38 pm

Hi
How do you access the serial? I think you may need to specify the baud speed. In my case, also a d1 mini, it worked with speed 115200 using the command:

microcom -s 115200 /dev/ttyUSB0

Also for me it worked in one USB port while the other couldn't do it.

rpi_nerd
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Re: unable to get REPL prompt

Post by rpi_nerd » Sat Jul 29, 2017 8:56 pm

I did specify the baud speed (screen /dev/ttyUSB0 115200).

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pythoncoder
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Re: unable to get REPL prompt

Post by pythoncoder » Sun Jul 30, 2017 9:19 am

@rpi_nerd Given that you've already got one board working I think we can take it that you know what you're doing ;) And given the fact that many of us (including myself) have used the D1 Mini we can take it that the board should work.

So my conclusion is that there's something amiss with your example. My guess is that the Flash chip is either too small or defective. Perhaps the Arduino firmware build is smaller? Given that it works with Arduino you might like to look at this thread which explains how to determine Flash size under Arduino viewtopic.php?f=16&t=1777&hilit=flash+size.
Peter Hinch

rpi_nerd
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Re: unable to get REPL prompt

Post by rpi_nerd » Sun Jul 30, 2017 1:52 pm

I just checked it under the Arduino IDE and it verified the the flash size is 4MB. Are there any tools available to check if the flash is good/bad?

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pythoncoder
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Re: unable to get REPL prompt

Post by pythoncoder » Sun Jul 30, 2017 4:35 pm

Given that you can't run MicroPython I think you'll need to look in the Arduino forums. But one thought that comes to mind is to try the verify option of esptool - something along these lines:

Code: Select all

esptool.py --port /dev/ttyUSB0 --baud 115200 write_flash --verify --flash_size=detect -fm dio 0 build/firmware-combined.bin
This will do a readback check of the firmware. Hardly an exhaustive test, but if it fails it would give an indication as to why it won't run.
Peter Hinch

rpi_nerd
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Re: unable to get REPL prompt

Post by rpi_nerd » Sun Jul 30, 2017 5:59 pm

I've been using the --verify option, and I've been getting verify OK every time.

sisodiakaran
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Re: unable to get REPL prompt

Post by sisodiakaran » Sun Jul 30, 2017 6:49 pm

Same issue with me. Posted here: https://electronics.stackexchange.com/q ... hon-prompt
Can any body identify the issue?

Thanks

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pythoncoder
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Re: unable to get REPL prompt

Post by pythoncoder » Mon Jul 31, 2017 7:01 am

I took a working Wemos D1 Mini and flashed a build produced last week. Initially it produced error messages saying the filesystem was corrupted. So I erased the flash and repeated, this time successfully.

If you guys are getting no REPL after an erase flash/reflash sequence I'm out of ideas. Could it be a problem with knockoff clone hardware?
Peter Hinch

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Balu
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Re: unable to get REPL prompt

Post by Balu » Mon Jul 31, 2017 5:15 pm

A couple of weeks ago I faced the same situation with an ESP8266 board. All the hints found in the net haven't been helpful. At the end I just flashed an older firmware version and then it worked fine.

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