Freescale Semiconductor MC68HC908MR32 - Manual (Page 108)

Input/Output (I/O) Ports (PORTS)
MC68HC908MR32 • MC68HC908MR16 Data Sheet, Rev. 6.1
108 Freescale Semiconductor
Figure 10-12 shows the port D input logic.
Figure 10-12. Port D Input Circuit
Reading address $0003 reads the voltage level on the pin. Table 10- 4 summarizes the operation of the
port D pins.
10.6 Port E
Port E is an 8-bit, special function port that shares five of its pins with the timer interface module (TIM)
and two of its pins with the serial communications interface module (SCI).
10.6.1 Port E Data Register
The port E data register (PTE) contains a data latch for each of the eight port E pins.
PTE[7:0] — Port E Data Bits
PTE[7:0] are read/write, software-programmable bits. Data direction of each port E pin is under the
control of the corresponding bit in data direction register E.
NOTE
Data direction register E (DDRE) does not affect the data direction of port
E pins that are being used by the TIMA or TIMB. However, the DDRE bits
always determine whether reading port E returns the states of the latches
or the states of the pins.
Table 10-4. Port D Pin Functions
PTD Bit Pin Mode
Accesses to PTD
Read Write
X (1)
1. X = don’t care
Input, Hi-Z (2)
2. Hi-Z = high impedance
Pin PTD[6:0] (3)
3. Writing affects data register, but does not affect input.
Address: $0008
Bit 7 6 5 4 3 2 1 Bit 0
Read:
PTE7 PTE6 PTE5 PTE4 PTE3 PTE2 PTE1 PTE0
Write:
Reset: Unaffected by reset
Figure 10-13. Port E Data Register (PTE)
READ PTD ($0003)
PTDx
INTERNAL
DAT
A B
US