Sony Ericsson GR64 - Manual (Page 57)

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5.11.2.1 Serial Data From Wireless modem (DFM1)
DFM1 is an output signal that the wireless modem uses to send data via UART1 to
the host application.
The electrical characteristics of this level-shifted signal are described in section
5.3.1.
5.11.2.2 Serial Data To Wireless modem (DTM1)
DTM1 is an input signal, used by the application to send data via UART1 to the
wireless modem.
The electrical characteristics of this level-shifted signal are described in section
5.3.1.
5.11.3 Control Signals (RTS1, CTS1, DTR1, DSR1, DCD1, RI)
Depending upon the user application, some, all, or none of the control signals may
be needed. Each of the control signals can alternatively be configured as a general
purpose IO. When hardware flow control is not used in communications between the
application and the wireless modem, some applications may require RTS and CTS to
be connected to each other at the wireless modem. Users should familiarize
themselves with the specific implementation of their UART.
UART1 converted signals, together with GND, DTM1 and DFM1 form a 9-pin RS232
data port.
The electrical characteristics of these level-shifted signals are described in section
5.3.1.
5.11.3.1 Hardware flow control RTS1 and CTS1
RTS and CTS provide a hardware flow control mechanism.
5.11.3.2 Request to Send (RTS1)
RTS is used to condition the DCE for data transmission. The default level is high by
internal pull up. The application must pull RTS low to enable data transmission from
the wireless modem. Similarly, the wireless modem asserts CTS low, indicating it is
ready to receive data transmission from the host.