I am working to build a product using the BW16 and have designed a custom PCB.
I have read the helpful post at [Resources] BW16 Troubleshooting Guide
After various difficulties, I managed to ‘clean’ a BW16 using the OTA method and that unit is now happily working with the Arduino boot loader.
For the second unit I was working on, I noticed that the default firmware has a command:
flash erase chip
And I thought I would try that. It worked. Even though an error message was reported in the middle of the errors, the phrase “Erase successful!” was emitted, and I found I could then enter the bootloader which starts by emitting 0x15 characters.
Now, for my third I used the ‘flash erase chip’ command again - and it appeared to work. However, if I use the “enter boot loader” sequence (EN low, LogTx low, EN high, Log Tx high) the module outputs:
Flash Downloader Started
instead of the series of 0x15 characters.
Neither the Realtek Image Tool nor the Arduino flash uploaders recognise this output.
If I start the unit normally (i.e. EN low, EN high), it outputs a # symbol (like the default firmware), and echoes commands typed, but the commands don’t do anything. If I hold down a key to make a very long command, I eventually see a message coming back saying <> - so there is something running there.
Not surprisingly, the second UART does not operate so I can no longer use AT commands.
Now during the prototyping, there was a brief moment when the module was exposed to 5V on its power pins - not 3.3, so I assumed I’d damaged the module in some subtle way, and replaced it with a fresh one.
However this fresh one ALSO has gone to the same state after using the ‘flash erase chip’ command in the standard firmware - it seems that this ‘bricks’ the device.
With that said, is there some different uploading tool (from the suppliers of the original firmware) which speaks the protocol which is expected from the “Flash Downloader Started” output? It would be nice to get these two modules back if I can.