User’s Manual
27
3.5 Serial Communication
The Coyote has two RS-232 serial ports, which can be configured as one RS-232 serial
channel (with RTS/CTS) or as two RS-232 (3-wire) channels. The Coyote also has one RS-
485 serial channel, one clocked CMOS serial channel, and two SPI serial ports with RS-
422. There is also a CMOS serial channel that serves as the programming/debug port.
The RS-232 and RS-485 serial ports operate in an asynchronous mode up to the baud rate
of the system clock divided by 8. An asynchronous port can handle 7 or 8 data bits. A 9th
bit address scheme, where an additional bit is sent to mark the first byte of a message, is
also supported. The CMOS serial channel and the two RS-422 SPI ports can also be oper-
ated in the clocked serial mode. In this mode, a clock line synchronously clocks the data in
or out. Either of the two communicating devices can supply the clock for the clocked
CMOS channel. As the master, the Coyote must supply the clock for the SPI ports.
The Coyote boards use all six serial ports. Serial Port A is used in the clocked serial mode
to provide cold-boot, download, and emulation functions. Serial Port B is multiplexed
between the two SPI RS-422 RabbitNet ports, SPI_1 and SPI_2. Clocked Serial Port C is
available as a basic CMOS voltage-level serial port. Serial Port D is used for RS-485 com-
munication, and Serial Ports E and F are used for RS-232 communication.
Table 5. Coyote Serial Port Configuration
Serial Port
Use
Header
A
Programming Port
J3 (RabbitCore module)
B
RabbitNet SPI (RS-422)
J4/J5
C
Clocked CMOS
J9
D
RS-485
J9
E
RS-232
J6
F
RS-232
J6