MC68HC908AZ60A_13 Datasheet, PDF (256/414 Pages) Freescale Semiconductor, Inc – Microcontrollers

Input/Output Ports
22.5 Port D
Port D is an 8-bit general-purpose I/O port. Note that PTD7 is only available on 64-pin package options.
22.5.1 Port D Data Register
Port D is a 8-bit special function port that shares seven of its pins with the analog to digital converter and
two with the timer interface modules.
Address:
Read:
Write:
Reset:
Alternative
Functions:
$0003
Bit 7
PTD7
6
5
4
3
2
PTD6
PTD5
PTD4
PTD3
PTD2
Unaffected by Reset
ATD14 ATD13 ATD12 ATD11 ATD10
TACLK
TBCLK
Figure 22-11. Port D Data Register (PTD)
1
PTD1
ATD9
Bit 0
PTD0
ATD8
PTD[7:0] — Port D Data Bits
PTD[7:0] are read/write, software programmable bits. Data direction of PTD[7:0] pins are under the
control of the corresponding bit in data direction register D.
ATD[14:8] — ADC Channel Status Bits
PTD6/ATD14/TACLK–PTD0/ATD8 are seven of the 15 analog-to-digital converter channels. The ADC
channel select bits, CH[4:0], determine whether the PTD6/ATD14/TACLK–PTD0/ATD8 pins are ADC
channels or general-purpose I/O pins. If an ADC channel is selected and a read of this corresponding
bit in the port B data register occurs, the data will be 0 if the data direction for this bit is programmed
as an input. Otherwise, the data will reflect the value in the data latch. (See Chapter 26
Analog-to-Digital Converter (ADC)).
NOTE
Data direction register D (DDRD) does not affect the data direction of port
D pins that are being used by the TIMA or TIMB. However, the DDRD bits
always determine whether reading port D returns the states of the latches
or a 0.
TACLK/TBCLK — Timer Clock Input Bit
The PTD6/ATD14/TACLK pin is the external clock input for the TIMA. The PTD4/ATD12/TBCLK pin is
the external clock input for the TIMB. The prescaler select bits, PS[2:0], select PTD6/ATD14/TACLK
or PTD4/ATD12/TBCLK as the TIM clock input. (See 25.8.4 TIMA Channel Status and Control
Registers and 20.8.4 TIMB Channel Status and Control Registers). When not selected as the TIM
clock, PTD6/ATD14/TACLK and PTD4/ATD12/TBCLK are available for general-purpose I/O. While
TACLK/TBCLK are selected corresponding DDRD bits have no effect.
MC68HC908AZ60A • MC68HC908AS60A • MC68HC908AS60E Data Sheet, Rev. 6
256
Freescale Semiconductor