Erasing flash via pycom-fwtool-cli with barebones LoPy4

[d.alvrzx]

Hello all:

I am attempting to erase the flash (and ultimately flash new firmware) to a LoPy4 that is barebones, connected to a breadboard, via the pycom-fwtool-cli tool. I currently have nothing else connected to the LoPy4 other than:

• 5V power from external power supply
• GND from external power supply
• TX, RX and GND to an FTDI USB to Serial converter
• GPIO0 (P2) connected to GND on boot (to enter bootloader mode)

When entering bootloader mode, I get the following message:

rst:0x1 (POWERON_RESET),boot:0x3 (DOWNLOAD_BOOT(UART0/UART1/SDIO_REI_REO_V2))
waiting for download

However, when I run pycom-fwtool-cli.exe -p COM7 erase_all, I get the following output:

Running in FTDI mode
Erasing the board can take up to 40 seconds.
Exception: Failed to connect to ESP32: Timed out waiting for packet header

Is it possible to do these sort of commands without an Expansion board? I am testing this on a breadboard because I want to be able to do this on a PCB I am working on.

I have already tested lowering the baud rate, but no luck!

Maybe, @Gijs, could you help me out?

Best,

Dan

[techykermit]

If you are able to connect to the device and run code, you can run

import os
os.fsformat("/flash")

If fsformat() doesn't work, it's because Pycom has changed the function name several times. Also try with makefs and mkfs (with the same arguments) in case you have a lower version.
`

[robert-hh]

@d-alvrzx Yes, you can do that without an expansion board. Did you close all other software connected to the LoPy4 before starting pycom-fwtool-cli?
You may also try to use esptool.py itself, which is the heart of pycom-fwtool-cli.py.

[d.alvrzx]

@robert-hh Thank you! So I uncovered what might be the problem: the commands coming from pycom-fwtool-cli only work once. Say, following this procedure:

• Connect P2 to GND while LoPy4 powered off
• Power on LoPy4
• Send pycom-fwtool-cli -p COM7 erase_all command
  • This command works, flash is erased in 15.98 seconds
• Send pycom-fwtool-cli -p COM7 flash -t LoPy4-1.20.2.rc6.tar.gz to flash new firmware
  • This command does not work, throws Exception: Failed to connect to ESP32: Timed out waiting for packet header
• Restart LoPy4 with P2 to GND
• Try pycom-fwtool-cli -p COM7 flash -t LoPy4-1.20.2.rc6.tar.gz again
  • This command works, firmware is flashed correctly.

So it seems I need a reset between each command? Is this how it should work?

EDIT: And yes, I did close all other software before opening the pycom fwtool.

[robert-hh]

@d-alvrzx You do not have to erase flash everytime you upload new firmware. Only if you think the flash is corrupted.
Besides that there is the -c option which you could try.

[d.alvrzx]

@robert-hh Thanks for the mention of the -c option! I did not know this, but it works! No more resets needed between commands.

And yes, I understand that I do not need to erase the flash every time I load a new firmware. But my example was trying to show that any 2 commands in a row had the same behaviour, for example:

1. Run pycom-fwtool-cli -p COM7 lpwan
   • The correct output is shown, with the SMAC, SID, PAC and LORA REGION
2. Run pycom-fwtool-cli -p COM7 lpwan once again, without resetting LoPy
   • The same error occurs: Exception: Failed to connect to ESP32: Timed out waiting for packet header

Now, with the -c option enabled, the procedure above works! Thanks so much!