Freescale Semiconductor MC68HC908MR32 Manual Do Utilizador
Input/Output (I/O) Ports (PORTS)
MC68HC908MR32 • MC68HC908MR16 Data Sheet, Rev. 6.1
108
Freescale Semiconductor
shows the port D input logic.
Figure 10-12. Port D Input Circuit
Reading address $0003 reads the voltage level on the pin.
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).
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.
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.
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