HC05V7GRSSLASHD datasheet(76/170 Pages) NXP

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SECTION 9: PARALLEL I/O

Page 62

MC68HC05V7 Specification Rev. 1.0

read of the Port A/C Data Register will return the logic state of the corresponding I/O pin.

The Port A/C data register is unaffected by reset.

9.1.2

PORT A/C DATA DIRECTION REGISTER

Each Port A/C I/O pin may be programmed as an input by clearing the corresponding bit in

the DDRA/C, or programmed as an output by setting the corresponding bit in the DDRA/C.

The DDRA can be accessed at address $0004. The DDRC can be accessed at address

$0006. The DDRA and DDRC are cleared by reset.

9.1.3

PORT A/C I/O PIN INTERRUPTS

The inputs of all eight bits of Port A and Port C are ANDed into the IRQ input of the CPU.

Each port has its own interrupt request latch to enable the user to differentiate between the

IRQ sources. The port IRQ inputs are falling edge sensitive only. Any Port A or Port C pin

can be disabled as an interrupt input by setting the corresponding DDR bit. Any Port A or

Port C pins that are outputs will not cause a port interrupt when the pin transitions from a 1

to a 0. However, since all inputs pins are ANDed together to form the interrupt signal, any

input pin that remains low will inhibit the interrupt flag bit from being set when subsequent

pins transition low.

NOTE:

The BIH and BIL instructions will only apply to the level on the IRQ pin

itself, and not to the internal IRQ input to the CPU. Therefore BIH and BIL

cannot be used to obtain the result of the logical combination of the eight

pins of Port A or Port C.

9.2

PORT B

Port B is an 8-bit bidirectional port. Each Port B pin is controlled by the corresponding bits

in a data direction register and a data register as shown in Figure 9-2. PB6 and PB7 are

shared with 16 Bit Timer functions. See SECTION 11 16-BIT TIMER. The Port B Data

at address $0005. Reset clears the DDRB register. The Port B Data Register is unaffected

by reset

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

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