Freescale Semiconductor MC68HC908MR16 Datasheet page 111

Figure 10-18 shows the port F I/O logic.
READ DDRF ($000D)
WRITE DDRF ($000D)
WRITE PTF ($0009)
READ PTF ($0009)
When bit DDRFx is a logic 1, reading address $0009 reads the PTFx data latch. When bit DDRFx is a
logic 0, reading address $0009 reads the voltage level on the pin. The data latch can always be written,
regardless of the state of its data direction bit.
DDRF Bit
0
1
1. X = don't care
2. Hi-Z = high impedance
3. Writing affects data register, but does not affect input.
Freescale Semiconductor
RESET
Figure 10-18. Port F I/O Circuit
Table 10-6. Port F Pin Functions
PTF Bit I/O Pin Mode
(1) (2)
X Input, Hi-Z
X Output
MC68HC908MR32 • MC68HC908MR16 Data Sheet, Rev. 6.1
DDRFx
PTFx
Table 10-6 summarizes the operation of the port F pins.
Accesses to DDRF
Read/Write
DDRF[6:0]
DDRF[6:0]
PTFx
Accesses to PTF
Read Write
(3)
Pin
PTF[6:0]
PTF[6:0] PTF[6:0]
Port F
111