Input/Output (I/O) Ports
Port F
MC68HC908MR16/MC68HC908MR32 — Rev. 4.0 Advance Information
MOTOROLA Input/Output (I/O) Ports 319
When bit DDREx is a logic 1, reading address $0008 reads the PTEx
data latch. When bit DDREx is a logic 0, reading address $0008 reads
the voltage level on the pin. The data latch can always be written,
regardless of the state of its data direction bit. Table 15-5 summarizes
the operation of the port E pins.
15.8 Port F
Port F is a 6-bit, special function port that shares four of its pins with the
serial peripheral interface module (SPI) and two pins with the serial
communications interface (SCI).
15.8.1 Port F Data Register
The port F data register (PTF) contains a data latch for each of the six
port F pins.
Table 15-5. Port E Pin Functions
DDRE
Bit PTE
Bit I/O Pin Mode
Accesses
to DDRE Accesses to PTE
Read/Write Read Write
0X(1)
1. X = don’t care
Input, Hi-Z(2)
2. Hi-Z = high impedance
DDRE[7:0] Pin PTE[7:0](3)
3. Writing affects data register, but does not affect input.
1 X Output DDRE[7:0] PTE[7:0] PTE[7:0]
Address: $0009
Bit 7654321Bit 0
Read: 0 0 PTF5 PTF4 PTF3 PTF2 PTF1 PTF0
Write: R R
Reset: Unaffected by reset
R= Reserved
Figure 15-16. Port F Data Register (PTF)