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Application Interface 2
The blu
2i
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 pre-
assigned 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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