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
5.11.3.1Hardware flow control RTS1 and CTS1
RTS and CTS provide a hardware flow control mechanism.
5.11.3.2Request 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.
5.11.3.3Clear To Send (CTS1)
CTS is asserted by the DCE to indicate that the host (DTE) may transmit data. When CTS is high, the host (DTE) is not permitted to transmit data. The table below shows the load characteristics for this signal.
5.11.3.4Data Terminal Ready (DTR1)
DTR indicates that the DTE is ready to receive data. It also acts as a hardware ‘hang- up’, terminating calls when switched high. The signal is active low. Users can define the exact behavior of DTR with an the AT&D command.
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