RTL7288DM board cannot download firmware in 1.8V mode

Technical Discussion
1

Hi,

I would like to operate the RTL-AMEBAD_MB_4V2 board in 1.8V mode. I set JP1 to VDD18, set UART_SEL J28 jumper to FT232, and plugged in VBUS USB3 (FT232) to PC. Then I tried to download test firmware from Arduino by pressing the UART_DOWNLOAD and RESET pin sequence. The board was unable to enter UART DOWNLOAD mode. When I switch JP1 to VDD33, it was able to enter UART DOWNLOAD mode and firmware was loaded.

How to enter UART DOWNLOAD mode in 1.8V supply mode on this board?

Thanks,
John

2

RTL7288 is not supported in opensource env

3

Hi Michael,
Thank you for your reply.
I’m not sure opensource has anything to do with my question though.
My question is very simple: this AMB21 board has jumper option to set it to 3.3V or 1.8V IO. When jumper is set to 3.3V, I could set the chip to UART_DOWNLOAD mode and download Arduino firmware. When jumper is set to 1.8V, it could no longer get into UART_DOWNLOAD mode (even after pressing the UART_DOWNLOAD-RESET pin sequence). Have you encountered this problem with AMB21 board?

Thank you.

4

Additionally, I was trying to download the Arduino code provided by Realtek. Not my own or any opensource.