I have a piece of new hardware and communication with the module works fine using RX,TX,RTS,CTS. I would like to to update the firmware on the HL6. Our hardware developers gave me RX,TX,RTS,CTS on test pins. I can tell the host controller not to touch these lines and completely disable the UART and pin configuration. So far I tried to update the software using a USB-UART (3.3V) converter that only provides RX and TX. It seems that is is not sufficient.
The hardware developers will give me an adapter for my PC’s native COM port using the MAX232 so I also have the flow control lines. Will this suffice?