101-1279 Rabbit Semiconductor, 101-1279 Datasheet - Page 27

• Manufacturer Part Number: 101-1279
• Description: PLASTIC ENCLOSURE FOR BL4S100
• Manufacturer: Rabbit Semiconductor

Specifications of 101-1279

• Accessory Type: Enclosure
• Product: Prototyping Accessories
• Processor Type: BL4S100
• Board Size: 146 mm x 96 mm x 16 mm
• Interface Type: Ethernet
• For Use With/related Products: BL4S100
• Lead Free Status / RoHS Status: Not applicable / Not applicable
• Other names: 316-1159

3.3 Serial Communication
The BL4S100 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 using the
ware function call. Table 5 summarizes the options.
The BL4S100 also has one CMOS serial channel that serves as the programming port.
All three serial ports operate in an asynchronous mode. 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. Serial Port A, the programming port, can be operated
alternately 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. The BL4S100
boards supports standard asynchronous baud rates up to 115,200 bps.
3.3.1 RS-232
The BL4S100 RS-232 serial communication is supported by an RS-232 transceiver. This
transceiver provides the voltage output, slew rate, and input voltage immunity required to
meet the RS-232 serial communication protocol. Basically, the chip translates the Rabbit
microprocessor’s CMOS signals to RS-232 signal levels. Note that the polarity is reversed
in an RS-232 circuit so that a +3.3 V output becomes approximately -10 V and 0 V is out-
put as +10 V. The RS-232 transceiver also provides the proper line loading for reliable
communication.
RS-232 can be used effectively at the BL4S100’s maximum baud rate for distances of up
to 15 m.
3.3.2 Programming Port
The BL4S100 has a 10-pin programming header. The programming port uses the Rabbit
4000 Serial Port A for communication, and is used for the following operations.
• Programming/debugging
• Cloning
The programming port is used to start the BL4S100 in a mode where the BL4S100 will
download a program and then execute the program. The programming port transmits
information to and from a PC while a program is being debugged.
The Rabbit 4000 startup-mode pins (SMODE0, SMODE1) are presented to the program-
ming port so that an externally connected device can force the BL4S100 to start up in an
BL4S100 User’s Manual
Table 5. Serial Communication Configurations
Mode
0
1
RS-232, 3-wire
RS-232, 5-wire
D
Serial Port
RS-232, 3-wire
CTS/RTS
F
serMode()
soft-
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