MC68HC908GZ8 Datasheet, PDF (212/344 Pages) Motorola, Inc – Microcontrollers

Input/Output (I/O) Ports
READ DDRD ($0007)
WRITE DDRD ($0007)
RESET
WRITE PTD ($0003)
VDD
DDRDx
PTDx
PTDPUEx
READ PTD ($0003)
INTERNAL
PULLUP
DEVICE
PTDx
Figure 17-15. Port D I/O Circuit
When bit DDRDx is a logic 1, reading address $0003 reads the PTDx data latch.
When bit DDRDx is a logic 0, reading address $0003 reads the voltage level on the
pin. The data latch can always be written, regardless of the state of its data
direction bit. Table 17-5 summarizes the operation of the port D pins.
Table 17-5. Port D Pin Functions
PTDPUE
Bit
DDRD
Bit
PTD
Bit
I/O Pin
Mode
1
0
X⁽¹⁾
Input, V_DD(2)
0
0
X
Input, Hi-Z⁽⁴⁾
X
1
X
Output
1. X = Don’t care
2. I/O pin pulled up to V_DD by internal pullup device.
3. Writing affects data register, but does not affect input.
4. Hi-Z = High imp[edance
Accesses
to DDRD
Read/Write
DDRD7–DDRD0
DDRD7–DDRD0
DDRD7–DDRD0
Accesses
to PTD
Read
Write
Pin
PTD7–PTD0⁽³⁾
Pin
PTD7–PTD0⁽³⁾
PTD7–PTD0
PTD7–PTD0
Data Sheet
212
Input/Output (I/O) Ports
MC68HC908GZ8
Freescale Semiconductor