RN52SRC Firmware update
I bought an RN52 some time ago. I wanted to use it as a A2DP transmitter, so I installed the RN52SRC v1.00 firmware on it, using the DFU utility.
Now I'd like to repurpose it as an A2DP receiver, and so I'd like to install RN52 v1.16 firmware. However, this time I haven't been able to get the DFU utility to work.
The RN52SRC documentation says that it supports DFU over UART. I've connected UART_TX and UART_RX to a PC and sent it the '$' command to switch it into DFU mode. It responds by stopping blinking LED0 and LED1, and putting out a few serial characters about once a second.
Then I start the DFU utility program and start the update. I see the transmit and receive LEDs of my serial to TTL converter blink, so I know some data goes both ways. Then after a few seconds I get the message:
Connection Error: a connection to the device could not be established
I've checked whether update over USB works instead, but no luck. And the docs only say DFU over UART works, they don't mention USB.
I've also wondered whether DTR/DSR or CTS/RTS signals are needed, so I've tried a few things there, but still nothing.
Any advice would be appreciated, or any information about the protocol. Is the DFU source code available (he asks doubtfully)?