#GEPRC Nano not responding. LED always on - SOLVED

71 messages · Page 1 of 1 (latest)

frail moth
supple sorrel
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Can you connect it to a different uart? Read the note at the top of every flashing guide about what a solid LED means

frail moth
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yes, I've tried all the three methods. 1 via WiFi , I simply can not make the led blink.

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the solid LED means established connection , which can't be true

supple sorrel
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Again, read the note at the top of the page I linked

frail moth
supple sorrel
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Did you?

frail moth
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Wow, thank you, I feel totally stupid... I tried the UART update also, but I suppose it didn't wotk because the Rx is in boot loader mode. How can I exit it? Should I add some pull up resistor? 1kOm probably?

supple sorrel
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Pull up or use a different uart

frail moth
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I moved it on a different one

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still get a solid led

supple sorrel
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Connect power only (no TX RX) and see if it blinks

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If not, it's soft bricked and you'll need to do a recovery flash

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!recovery

desert crowBOT
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Follow these steps to recover a bricked RX:

- Move the 5v wire going to the receiver to a 5V pad that only powers on when a LiPo is connected 
- Disable Telemetry in Betaflight
- Save and Reboot
- Close Betaflight Configurator and unplug USB and LiPo
- Bridge the boot pads or hold down the boot button on the receiver
- Plug in USB
- Click "Build and Flash" in the ExpressLRS Configurator, selecting via Betaflight Passthrough method
- Wait for the line PASSTHROUGH DONE to appear
- Plug in LiPo (with boot button held down/bridged)
- Wait for the process to finish (with success hopefully)
- Unplug everything, unbridge the boot pads, then power on to confirm the LED blinks, and then goes into WiFi mode

Video Tutorial: https://www.youtube.com/watch?v=jYLwaWBkM_A

YouTube
DeltaGeek
How to Recover a Bricked ExpressLRS Receiver

https://www.expresslrs.org/2.0/quick-start/unbricking/

â–¶ Play video
frail moth
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yes, I did this several times, it does not blink with power only

supple sorrel
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You did the recovery flash?

frail moth
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No, I'm now reading it

supple sorrel
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Do you have a FTDI adapter?

frail moth
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yes, I have

supple sorrel
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That is usually the easiest and most foolproof way to recover

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Just connect the receiver to that and flash

frail moth
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well, I think I tried that, you mean this step :

supple sorrel
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Yes

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And what happened?

frail moth
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should I hold the button on the Rx while doing it?

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'Connecting......................................_____\r\n' +
'\r\n' +
'A fatal error occurred: Failed to connect to ESP8266: Timed out waiting for packet header\r\n' +

supple sorrel
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Can you show a photo of the wiring and the log?

frail moth
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I will resolder the wires for the FTDI and try again

supple sorrel
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I'm on mobile, can you paste an uncompressed version?

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Just the last 100 lines or so is fine

frail moth
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here is the wiring, now I try to update it via FTDI

supple sorrel
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If that doesn't work I would remove the FC wires

frail moth
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the FC is not connected, I simply left the connector

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'Building in release mode\r\n' +
"PLATFORM : 'espressif8266'\r\n" +
"BUILD ENV: 'DIY_900_RX_ESP8285_SX127X_VIA_UART'\r\n" +
'Retrieving maximum program size .pio\build\DIY_900_RX_ESP8285_SX127x_via_UART\firmware.elf\r\n' +
'Checking size .pio\build\DIY_900_RX_ESP8285_SX127x_via_UART\firmware.elf\r\n' +
'Advanced Memory Usage is available via "PlatformIO Home > Project Inspect"\r\n' +
'RAM: [==== ] 43.1% (used 35340 bytes from 81920 bytes)\r\n' +
'Flash: [==== ] 37.2% (used 380516 bytes from 1023984 bytes)\r\n' +
'Building .pio\build\DIY_900_RX_ESP8285_SX127x_via_UART\firmware.bin\r\n' +
'Creating BIN file ".pio\build\DIY_900_RX_ESP8285_SX127x_via_UART\firmware.bin" using "C:\Users\Tisho\.platformio\packages\framework-arduinoespressif8266\bootloaders\eboot\eboot.elf" and ".pio\build\DIY_900_RX_ESP8285_SX127x_via_UART\firmware.elf"\r\n' +
'Configuring upload protocol...\r\n' +
'AVAILABLE: espota, esptool\r\n' +
'CURRENT: upload_protocol = esptool\r\n' +
'Looking for upload port...\r\n' +
'Using manually specified: COM5\r\n' +
'Uploading .pio\build\DIY_900_RX_ESP8285_SX127x_via_UART\firmware.bin\r\n' +
'esptool.py v3.0\r\n' +
'Serial port COM5\r\n' +
'Connecting......................................_____\r\n' +
'\r\n' +
'A fatal error occurred: Failed to connect to ESP8266: Timed out waiting for packet header\r\n' +
'\r\n'
},
stack: [ undefined ],
level: 'error',
message: 'flash error'
}
{
context: { arg: { buildInProgress: false } },
level: 'info',
message: 'received a request to update build status'
}

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I could see leds on the FTDI blink for some time, like it was sending something...

supple sorrel
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Is that the correct COM port? Do you have anything else open like Cura? What does the FTDI show up as in device manager?

frail moth
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The port is available, I can open it via putty. I see the FTDI leds flashing....

supple sorrel
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Try swapping TX and RX?

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Some FTDI adapters have them labeled backwards

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Are you holding down the boot button when applying power?

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Sorry, on the road now. Might not be able to respond for a bit.

supple sorrel
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Any luck?

frail moth
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Thank you very much for your help. The FDTI adapter is working, I use it often to connect to GPS modules. Seems like this is a common problem with esp8266. Probably voltage levels are not ok. Will try solutions from arduino forums, will borrow a different type of FDTI adapter from a friend.

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Anyway, this is really not acceptable for a product. A brand new GEPRC ELRS Rx which is bricked out of the box. I simply removed the old Rx and connected this one to a perfectly working setup. I am not sure that it got bricked by the FC. I never tried it with power wires connected only. And I use this Omnibus F4Pro setup on three different planes with three ELRS receivers without any problems - HappyModel, BetaFPV and Jhemcu.

frail moth
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So, i set the baud rate to 7480 and connected via putty, this is what I get

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So, i set the baud rate to 74880 and connected via putty, this is what I get

image.png
frail moth
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YESSS, I FIXED IT!
The debug message made me dig deeper.
It turned out it reported 3 important pins.

image.png
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The ESP8266 documentation claims:

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So obviously GPIO15 was HIGH, which was preventing the CPU from starting....

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I found where GPIO15 on the chip is located....

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then started tracing it on the board

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And then I saw a problem

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it looked like a resistor was missing

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I compared with a real image from the web(top), and it was clear that something black - resistor, was missing

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so I soldered a new one, with a value 1kOhm - I felt that should be tha value... 🙂

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And successfully flashed with the FDTI ..... Wow... took me several nights... 🙂 But now it is working 🙂

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GEPRC Nano not responding. LED always on - SOLVED