Using The Serial Ports - Rabbit RabbitCore RCM4200 User Manual

Table 3 summarizes the possible parallel port pins for the serial ports and their clocks.
Table 3. Rabbit 4000 Serial Port and Clock Pins
TXA
Serial Port A
(program- RXA
ming port)
SCLKA
TXB
Serial Port B
(used by A/D
RXB
converter on
RCM4200)
SCLKB
TXC
Serial Port C
(shared by RXC
serial flash)
SCLKC

4.2.1.1 Using the Serial Ports

The receive lines on the RCM4200 serial ports do not have pull-up resistors. If you are
using the serial ports without a receiver chip (for example, for RS-422, RS-232, or RS-485
serial communication), the absence of a pull-up resistor on the receive line will likely lead
to line breaks being generated since line breaks are normally generated whenever the
receive line is pulled low. If you are operating a serial port asynchronously, you can inhibit
character assembly during breaks by setting bit 1 in the corresponding Serial Port
Extended Register to 1. Should you need line breaks, you will have to either add a pull-up
resistor on your motherboard or use a receiver that incorporates the circuits to have the
output default to the nonbreak levels.
The Dynamic C
RS232.LIB
NOCHARASSYINBRK
#define RS232_NOCHARASSYINBRK
This macro is already defined so that it is the default behavior for the sample programs in
the Dynamic C
SAMPLES\RCM4200\SERIAL
36
PC6, PC7, PD6
PC7, PD7, PE7
PB1
PC4, PC5, PD4
PC5, PD5, PE5
PB0
PC2, PC3
PC3, PD3, PE3
PD2, PE2, PE7, PC7
library requires you to define the macro
to inhibit break-character assembly for all the serial ports.
TXD
Serial Port D RXD
SCLKD
TXE
Serial Port E
RXE
(RCM4210
RCLKE
only)
TCLKE
RCLKE must be selected to be on the same parallel
port as TXE.
folder.
PC0, PC1
PC1, PD1, PE1
PD0, PE0, PE3, PC3
PD6, PC6, PE6
PD7, PC7, PE7
PD5, PC5, PE5
PD4, PC4, PE4
RS232_
RabbitCore RCM4200