MC908JB16DWE Datasheet, PDF (277/332 Pages) Freescale Semiconductor, Inc – Microcontrollers

Input/Output (I/O) Ports
NOTE:
Data direction register E (DDRE) does not affect the data direction of
port E pins that are being used by the TIM. However, the DDRE bits
always determine whether reading port E returns the states of the
latches or the states of the pins.
14.6.2 Data Direction Register E
Data direction register E determines whether each port E pin is an input
or an output. Writing a logic 1 to a DDRE bit enables the output buffer for
the corresponding port E pin; a logic 0 disables the output buffer.
Address: $0009
Bit 7
6
5
4
3
2
1
Read: 0
0
0
DDRE4 DDRE3 DDRE2 DDRE1
Write:
Reset: 0
0
0
0
0
0
0
= Unimplemented
Figure 14-12. Data Direction Register E (DDRE)
Bit 0
DDRE0
0
DDRE[4:0] — Data Direction Register E Bits
These read/write bits control port E data direction. Reset clears
DDRE[4:0], configuring all port E pins as inputs.
1 = Corresponding port E pin configured as output
0 = Corresponding port E pin configured as input
NOTE: Avoid glitches on port E pins by writing to the port E data register before
changing data direction register E bits from 0 to 1.
Figure 14-13 shows the port E I/O circuit logic.
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor
Input/Output (I/O) Ports
Technical Data
277