s908gr32ag3vfa Freescale Semiconductor, Inc, s908gr32ag3vfa Datasheet - Page 150

• Manufacturer Part Number: s908gr32ag3vfa
• Description: M68hc08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Input/Output (I/O) Ports
12.9.2 Data Direction Register G
Data direction register G (DDRG) determines whether each port G pin is an input or an output. Writing a 1
to a DDRG bit enables the output buffer for the corresponding port G pin; a 0 disables the output buffer.
DDRG7–DDRG0 — Data Direction Register G Bits
Figure 12-25
When bit DDRGx is a 1, reading address $0441 reads the PTGx data latch. When bit DDRGx is a 0,
reading address $0441 reads the voltage level on the pin. The data latch can always be written,
regardless of the state of its data direction bit.
150
1. X = Don’t care
2. Hi-Z = High impedance
3. Writing affects data register, but does not affect input.
These read/write bits control port G data direction. Reset clears DDRG7–DDRG0], configuring all port
G pins as inputs.
DDRG
Bit
0
1
1 = Corresponding port G pin configured as output
0 = Corresponding port G pin configured as input
Address:
shows the port G I/O logic.
PTG
X
Bit
Avoid glitches on port G pins by writing to the port G data register before
changing data direction register G bits from 0 to 1.
Reset:
Read:
X
Write:
(1)
MC68HC908GR60A • MC68HC908GR48A • MC68HC908GR32A Data Sheet, Rev. 5
READ DDRG ($0445)
WRITE DDRG ($0445)
WRITE PTG ($0441)
READ PTG ($0441)
DDRG7
$0445
Bit 7
0
Input, Hi-Z
Figure 12-24. Data Direction Register G (DDRG)
I/O Pin
Output
Mode
DDRG6
6
0
(2)
Table 12-8. Port G Pin Functions
RESET
Figure 12-25. Port G I/O Circuit
DDRG5
5
0
Accesses to DDRG
DDRG7–DDRG0
DDRG7–DDRG0
Table 12-8
Read/Write
DDRG4
NOTE
DDRGx
PTGx
4
0
DDRG3
summarizes the operation of the port G pins.
3
0
DDRG2
PTG7–PTG0
2
0
Read
Pin
DDRG1
Accesses to PTG
1
0
Freescale Semiconductor
DDRG0
Bit 0
PTGx
0
PTG7–PTG0
PTG7–PTG0
Write
(3)