2Application Interface

The blu2i Module is equipped with a 40-pin 0.5mm pitch board to board connector that connects to the application platform. Electrical and mechanical characteristics of the board-to-board connector are specified in Chapter 3.

•Serial interface (see Section 3.0)

•Electrical specification of the interface (see Section 3.1)

2.1 Serial Interface

UART_TX, UART_RX, UART_RTS and UART_CTS form a conventional asynchronous serial data port. The interface is designed to operate correctly when connected to other UART devices such as the 16550A. The signalling levels are nominal 0V and 3.3V and are inverted with respect to the signalling on an RS232 cable. The interface is programmable over a variety of bit rates; no, even or odd parity; stop bit and hardware flow control. The default condition on power-up is preassigned in the external Flash. Two-way hardware flow control is implemented by UART_RTS and UART_CTS. UART_RTS is an output and is active low. UART_CTS is an input and is active low. These signals operate according to normal industry convention.

By writing different values to the S register the UART_RI can be continuously polled to detect incoming communication. The UART_RI signal serves to indicate incoming calls.

UART_DSR is an active low input. It should be connected to DTR output of the host. When the module is running in high speed mode (See definition for S Register 512), this pin should be asserted by the host to ensure connection is maintained. A deassertion is taken to mean that the connection should be dropped, or an online command mode is being requested.

The module communicates with the customer application using the following signals:

RS-232

•Port /TXD @ application sends data to the module’s UART_RX signal line

•Port /RXD @ application receives data from the module’s UART_TX signal line

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