20-668-0024 Rabbit Semiconductor, 20-668-0024 Datasheet - Page 87

• Manufacturer Part Number: 20-668-0024
• Description: IC CPU RABBIT4000 128-LQFP
• Manufacturer: Rabbit Semiconductor

Specifications of 20-668-0024

• Processor Type: Rabbit 4000 8-bit
• Speed: 60MHz
• Voltage: 2.5V, 2.7V, 3V, 3.3V
• Mounting Type: Surface Mount
• Package / Case: 128-LQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Features: -
• Other names: 20-668-0022; 316-1078

9.1 Overview
Parallel Port B is a byte-wide port with each bit programmable for direction. The Parallel
Port B pins are also used to access other peripherals on the chip—the slave port, the
auxiliary I/O address bus, and clock I/O for clocked serial mode option for Serial Ports A
and B. The Slave Port Control Register (SPCR) is used to configure how Parallel Port B is
used when selecting the slave port or the auxiliary I/O bus modes.
When the slave port is enabled, either under program control or during parallel bootstrap,
Parallel Port B pins carry the Slave Attention output signal, and four of the inputs carry the
Slave Read strobe, Slave Write strobe, and Slave Address bits. The Slave Chip Select can
also be programmed to come from a Parallel Port B pin.
When the auxiliary I/O bus option is enabled, either six or eight pins carry the external I/O
address signals selected in SPCR.
Two pins are used for the clocks for Serial Ports A and B when they are configured for the
clocked serial mode. These two inputs can be used as clock outputs for these ports if
selected in the respective serial port control registers. Note that the clocked serial output
clock selection overrides all other programming for the two relevant Parallel Port B pins.
Chapter 9 Parallel Port B
Table 9-1. Parallel Port B Pin Alternate Output Functions
Pin Name
PB7
PB6
PB5
PB4
PB3
PB2
PB1
PB0
Slave Port
/SLVATN
/SWR
/SRD
/SCS
SA1
SA0
—
—
9. P
Serial Ports
SCLKA
SCLKB
A–D
—
—
—
—
—
—
ARALLEL
Auxiliary I/O
Bus
IA5
IA4
IA3
IA2
IA1
IA0
IA7
IA6
P
ORT
B
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