Using The Serial Ports - Rabbit RabbitCore RCM4100 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 RXA
SCLKA
TXB
Serial Port B RXB
SCLKB
TXC
Serial Port C RXC
SCLKC
TXD
Serial Port D RXD
SCLKD

4.2.1.1 Using the Serial Ports

The receive lines on the RCM4100 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
RS232_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\RCM4100\SERIAL
34
PC6, PC7, PD6
PC7, PD7, PE7
Serial Port E
PB1
PC4, PC5, PD4
PC5, PD5, PE5
PB0
Serial Port F
PC2, PC3
PC3, PD3, PE3
PD2, PE2, PE7, PC7
PC0, PC1
RCLKE and RCLKF must be selected to be on the
same parallel port as TXE and TXF respectively.
PC1, PD1, PE1
PD0, PE0, PE3, PC3
library requires you to define the macro
to inhibit break-character assembly for all the serial ports.
folder.
TXE PD6, PE6, PC6
RXE PD7, PE7, PC7
RCLKE PD5, PE5, PC5
TCLKE PD4, PE4, PC4
TXF PD2, PE2, PC2
RXF PD3, PE3, PC3
RCLKF PD1, PE1, PC1
TCLKF PD0, PE0, PC0
RabbitCore RCM4100