MC68HC08XL36 Datasheet, PDF (292/362 Pages) Freescale Semiconductor, Inc – HCMOS Microcontroller Unit

Freescale Semiconductor, Inc.
Input/Output Ports
DDRH3–DDRH0 — Data Direction Register H Bits
These read/write bits control port H data direction. Reset clears
DDRH3–DDRH0, configuring all port H pins as inputs.
1 = Corresponding port H pin configured as output
0 = Corresponding port H pin configured as input
NOTE: Avoid glitches on port H pins by writing to the port H data register before
changing the data direction register H bits from 0 to 1.
Figure 25 shows the port H I/O logic.
READ DDRH ($000F)
WRITE DDRH ($000F)
RESET
DDRHx
WRITE PORTH ($000B)
PHx
PHx
READ PORTH ($000B)
Figure 25. Port H I/O Circuit
When bit DDRHx is a logic 1, reading address $000B reads the PHx data
latch. When bit DDRHx is a logic 0, reading address $000B reads the
voltage level on the pin. The data latch can always be written, regardless
of the state of its data direction bit. Table 9 summarizes the operation of
the port H pins.
Table 9. Port H Pin Operation
Data Direction Bit
I/O Pin Mode
0
Input, high-impedance
1
Output
1. Writing affects data register, but does not affect input.
Access to Data Bit
Read
Pin
Write
Latch⁽¹⁾
Latch
Latch
MC68HC08XL36
292
Input/Output Ports
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