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Programmer’s Reference
Copyright © ARM Limited 2000. All rights reserved.
4-29
4.5.4
Using the GPIO pins
The direction of the GPIO pins are controlled by the state of bits 9:0 in the IO port
direction register. Setting a bit to 1 defines the corresponding pin as an output. Setting
a bit to 0 defines the corresponding pin as an input.
Writing to the IO port data register controls the state of the pins that are defined as
outputs. Reading the IO port data register returns the current states of the IO port pins.
The GPIO pins can be configured to generate interrupts on rising or falling edges.
A number of the GPIO pins have predefined functionality for the P1100. For example,
GPIO8 is used as a DAA off hook signal (see General purpose input/output pin block
on page 3-41).
4.5.5
UCB1200 interrupts
The UCB1200 interrupt request signal UCB_IRQ is routed to the interrupt controller
block of system controller PLD and then to the interrupt on the GPIO1 pin of the
SA-1100. The interrupt handler must read the PLD interrupt register to determine the
source of any interrupt on this pin. Bit 1 in the PLD interrupt register is a 1 if the
UCB1200 is the source of the pending interrupt.
The UCB1200 provides the following interrupt sources:
•
10 input/output pins
7
Audio control register A
6
Telecom control register B
5
Telecom control register A
4
Interrupt status/clear register
3
Falling edge interrupt enable
register
2
Rising edge interrupt enable
register
1
IO port direction register
0
IO port data register
Table 4-20 UCB1200 register summary
Address Name
Содержание Prospector P1100
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