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Pin
PF0/BREQ/IRQ2
10.13
Port G
10.13.1 Overview
Port G is a 5-bit I/O port and also used as external interrupt input pins (IRQ6, IRQ7) and bus
control signal output pins (CS0 to CS3, CAS, OE).
Figure 10-23 shows the configuration of port G pins.
Port G pin
PG4 /
PG3 /
Port G
PG2 /
PG1 /
PG0 /
Selection Method and Pin Functions
The pin function is switched as shown below according to the combination of
the operating mode, and bits BRLE and PF0DDR.
Operating
Mode
BRLE
PF0DDR
Pin function
input pin
CS0
CS1
CS2
CS3 / OE / IRQ7
CAS / IRQ6
Figure 10-23 Port G Pin Functions
Modes 4 to 6
0
0
1
PF0
PF0
output pin
Pin Functions in Modes 4 to 6
PG4 /
(input) /
PG3 /
(input) /
PG2 /
(input) /
PG1 /
(input) /
PG0 /
(input / output) / CAS (output) / IRQ6 (input)
Pin Functions in Mode 7
PG4 /
(input / output)
PG3 /
(input / output)
PG2 /
(input / output)
PG1 /
(input / output) / IRQ7 (input)
PG0 /
(input / output) / IRQ6 (input)
1
—
0
BREQ
PF0
input pin
input pin
IRQ2 input pin
CS0 (output)
CS1 (output)
CS2 (output)
CS3 (output) / OE (output) / IRQ7 (input)
Mode 7
—
1
PF0
output pin
397
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