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Line Name
UART1_DTR
UART1_DSR
UART1_RI
UART1_DCD
For standard RS232 communications, such as that required when connecting to a PC, the UART signals must be driven through
an RS232 transceiver.
In order to configure the c18 to communicate through UART1, RS232 mode or RS232 + USB mode should be selected by
setting the configuration pins (OPT1, OPT2, AUDIO_IN and USB_VBUS). See "c18 OPERATING MODES" on page 17.
If the required mode of communication was set on power-up, the module does not respond to AT commands until the power-up
sequence completes. This sequence can take six to seven seconds, and is indicated by the UART1_CTS signal being high. After
power-up completes, the module asserts the UART1_CTS signal low, indicating that the module is ready to communicate and
receive AT commands.
If the module has been powered up but not configured for RS232 mode, entering RS232 mode is fast. It is indicated by the
UART1 CTS signal going low.
3.6.3
UART2
UART2 can support up to a four-wire interface. Two UART2 signals (RXD and CTS) are shared with R-UIM signals (UIM
DATA and UIM CLK). For this reason, only one of these interfaces can be used at a time. Figure 12 shows the UART2 interface
UART2 is hardware supported.
Note
98-08901C63-A
Table 9. UART1 Signal Definitions (Continued)
Line Function
Data terminal ready
Data set ready
Ring indicator
Data carrier detect
Definition
The DTE sets this line to logical 1 when it is
ready for communication with the DCE
(c18).The c18 thereby recognizes that it is
connected to an active DTE.
By setting this line to logical 1, the c18
indicates to the DTE that a connection has
been established with the other side, and that
data can now be sent.
Using this line, the c18 indicates to the DTE
(PC) that there is an incoming call.
Using this line, the c18 indicates to the DTE
(PC) that it has received a carrier signal from
the other end of the line.
Hardware Description
.
25
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