Uart1; Figure 11. Uart1 Interface; Table 9. Uart1 Signal Definitions - Motorola c18 Developer's Manual

Hardware Description
3.6.2

UART1

The c18 UART interface supports data-rates of up to 230 Kbps. The default data-rate is 19.2 Kbps. Figure 11 shows the
UART1 interface.
UART signals are low CMOS-level signals (0 to 2.8 V) that can be connected directly to the host UART. c18 input signals (such
as TXD, RTS and DTR signals) are buffered, making them capable of receiving signal levels up to 5.0 V. Signals are referenced
to the GND.
All unused UART input signals, or input signals that can become disconnected (such as those for cable removal),
should be pulled down. The suggested pull-down resistor is a 100k
Note
Table 9 lists the UART1 interface signal definitions.
Line Name
UART1_TXD
UART1_RXD
UART1_RTS
UART1_CTS
24
TXD
RXD
RTS
HOST
UART
(DTE)
CTS
DTR
DSR
DCD
RI

Figure 11. UART1 Interface

Table 9. UART1 Signal Definitions

Line Function
Transmitted data
Received data
Request to send
Clear to send
TXD
100kΩ
RXD
RTS
100kΩ
C18
UART(1)
(DCE)
CTS
DTR
100kΩ
DSR
DCD
RI
Ω
resistor.
Definition
Data line from DTE (PC) to c18 (DCE).
Data line from c18 (DCE) to DTE (PC).
By setting this line to logical 1, the DTE asks the
c18 (DCE) if it is ready to receive data.
When it is ready to receive data, the c18 sets this
line to logical 1 following the RTS.
98-08901C63-A