How to use an external CH340 USB to serial port board to download programs? In the later stages of the project, I do not want to use the micro USB interface to download the program, which is not convenient for debugging when integrated into some shells.
At least I wonder if there is a way to connect the micro USB through a cable? If possible, please also let me know the wiring schematic of the micro USB part. Thank you. I’m not sure if anyone has tried this tutorial before, as I haven’t seen a beginner friendly tutorial yet.
you can use the 25, 26 pin to connect with ch340 tx, rx for the download.
https://www.amebaiot.com/en/amebapro2-amb82-mini-arduino-getting-started/
thank you,i will try
Confirmed working: flashing AMB82-mini via external USB-UART adapter (CH340G) connected to pins 25/26.
Adapter used: 5 Pcs UART-TTL USB Adapter with CH340G Chip,
Make sure to use 3.3V mode
Connections:
- CH340G TX → AMB82-mini pin 26 (LOG_RX / PF3)
- CH340G RX → AMB82-mini pin 25 (LOG_TX / PF4)
- CH340G GND → AMB82-mini GND
Note the cross-connection: TX goes to RX and RX goes to TX — this is standard UART wiring but easy to mix up.
Physical location of pins 25/26: these are PF4 (pin 25) and PF3 (pin 26), located in the second row of holes next to the main GPIO header (pins 0, 1, 2, 3…). They are not part of the main row — see photo and board silkscreen. I’ve attached a photo and schematic highlighting their location.
To enter flash mode manually: hold BURN button, press RESET, release BURN — then upload from Arduino IDE as usual.
Hope this helps anyone trying to flash without using the onboard Micro USB.
Also, I use same Serial for printing all data for monitoring work after booting
$8735b>========== SERIAL BEGIN ==========
If you see this on pin 25/26, Serial maps to LOGUART!
==================================
========== PRINTF BEGIN ==========
If you see this on pin 25/26, printf goes to LOGUART!
==================================
\>>> TEST STARTED <
\[Serial\] tick #1 at 2057 ms
\[printf\] tick #1 at 2057 ms
\[Serial\] tick #2 at 3057 ms
\[printf\] tick #2 at 3057 ms
\[Serial\] tick #3 at 4057 ms
\[printf\] tick #3 at 4057 ms
\[Serial\] tick #4 at 5057 ms
\[printf\] tick #4 at 5057 ms
\[Serial\] tick #5 at 6057 ms
\[printf\] tick #5 at 6057 ms
\`\`\`
Example code for serial output
loguart_test.ino.zip (1.2 KB)
P.S. But still your have to push reset button on the body to have “upload mode” and if Ameba inside case you have to open it. No auto uplad mode as ESP has