I’m trying to program a HiLo module via a host microcontroller (the HiLo module is already embedded in a product). I am trying to follow the requirements you have suggested but can’t get it to work - the HiLo upgrader fails to detect the HiLo module. Is it possible to program with only TX and RX or are all the control signals (DCD, DTR, RTS, CTS) also required for programming?
Well… I also would like to have this info. I tried to create a loopback from my CPU serial debug UART (connected with a FT232 to a PC) and the Hilo interface UART. Just a loopback between TX and RX, but I think it is needed also other signals.
Can anyone confirm that TX and RX are sufficient? What about other UART signals? What about POK, RESET, etc…??
I have successfully updated HL6528 module just with RX/TX lines from USB to UART converter (CP2102) and conecting DTR pin to GND.
I have done upgrading with HiloUpgrader software for Windows that Sierra Wireless provided.
Hope this helps.