UART Transport

Connecting to the Blecon Modem over UART

The Blecon modem supports UART as a transport protocol. The UART must be used with a 115200bps baudrate, no parity and one stop bit, and hardware flow control (RTS/CTS) for physical UARTs.

Modems with a USB interface also expose the UART transport as a virtual serial port on a device with Vendor ID 0x36ca and Product ID 0x0001.

All data sent on the UART link is hex-encoded, as little endian. All frames are separated by a carriage return (CR) and line feed (LF) control character. The CR character is optional when sending frames to the modem.

A transaction is made of a request frame (on the modem's RX line) and response frame (TX line). The modem only supports one request to be pending at a given time.

When the modem needs to signal an event to the host MCU, it sends an event frame on the modem's TX line. Please note the event frame can be received at any time.

Request frame

The structure of a request frame is:

	2 characters	4 characters	n*2 characters	2 characters
RX	01	Request size (hex-encoded, LE)	Request (hex-encoded)	<CR><LF>

Response frame

The structure of a response frame is:

	2 characters	4 characters	n*2 characters	2 characters
TX	01	Response size (hex-encoded, LE)	Response (hex-encoded)	<CR><LF>

Event frame

The structure of an event frame is:

	2 characters	2 characters
TX	02	<CR><LF>