MC68HC908AS32A Datasheet, PDF (161/280 Pages) Freescale Semiconductor, Inc – Microcontrollers

READ DDRE ($000C)
WRITE DDRE ($000C)
RESET
WRITE PTE ($0008)
DDREx
PTEx
Port F
PTEx
READ PTE ($0008)
Figure 13-15. Port E I/O Circuit
When bit DDREx is a 1, reading address $0008 reads the PTEx data latch. When bit DDREx is a 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 13-5 summarizes the operation of the port E pins.
Table 13-5. Port E Pin Functions
DDRE PTE
Bit
Bit
I/O Pin
Mode
Accesses to DDRE
Read/Write
0
X
Input, Hi-Z
DDRE[7:0]
1
X
Output
DDRE[7:0]
X = don’t care
Hi-Z = high impedance
1. Writing affects data register, but does not affect input.
Accesses to PTE
Read
Write
Pin
PTE[7:0]⁽¹⁾
PTE[7:0]
PTE[7:0]⁽¹⁾
13.7 Port F
Port F is a 4-bit special function port that shares four of its pins with the TIM.
13.7.1 Port F Data Register
The port F data register contains a data latch for each of the four port F pins.
Address:
Read:
Write:
Reset:
Alternative Function:
$0009
Bit 7
6
5
4
3
2
0
0
0
0
PTF3
PTF2
= Unimplemented
Unaffected by reset
TCH5
TCH4
Figure 13-16. Port F Data Register (PTF)
1
PTF1
TCH3
Bit 0
PTF0
TCH2
PTF[3:0] — Port F Data Bits
These read/write bits are software programmable. Data direction of each port F pin is under the control
of the corresponding bit in data direction register F. Reset has no effect on PTF[3:0].
MC68HC908AS32A Data Sheet, Rev. 2.0
Freescale Semiconductor
161