MC68HC908LB8CPE Freescale Semiconductor, MC68HC908LB8CPE Datasheet - Page 137

• Manufacturer Part Number: MC68HC908LB8CPE
• Description: IC MCU 8K FLASH 8MHZ 20DIP
• Manufacturer: Freescale Semiconductor
• Series: HC08r

Specifications of MC68HC908LB8CPE

• Core Processor: HC08
• Core Size: 8-Bit
• Speed: 8MHz
• Peripherals: LVR, POR, PWM
• Number Of I /o: 18
• Program Memory Size: 8KB (8K x 8)
• Program Memory Type: FLASH
• Ram Size: 128 x 8
• Voltage - Supply (vcc/vdd): 4.5 V ~ 5.5 V
• Data Converters: A/D 7x8b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 20-DIP (0.300", 7.62mm)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Connectivity: -

14.3.2 Data Direction Register B
Data direction register B (DDRB) determines whether each port B pin is an input or an output. Writing a
1 to a DDRB bit enables the output buffer for the corresponding port B pin; a 0 disables the output buffer.
DDRB7–DDRB0 — Data Direction Register B Bits
Figure 14-8
When bit DDRBx is a 1, reading address $0001 reads the PTBx data latch. When bit DDRBx is a 0,
reading address $0001 reads the voltage level on the pin. The data latch can always be written,
regardless of the state of its data direction bit.
Freescale Semiconductor
These read/write bits control port B data direction. Reset clears DDRB7–DDRB0, configuring all port
B pins as inputs.
1 = Corresponding port B pin configured as output
0 = Corresponding port B pin configured as input
shows the port B I/O logic.
Address:
Avoid glitches on port B pins by writing to the port B data register before
changing data direction register B bits from 0 to 1.
Reset:
Read:
Write:
READ DDRB ($0005)
WRITE DDRB ($0005)
WRITE PTB ($0001)
READ PTB ($0001)
DDRB7
$0005
Bit 7
0
Figure 14-7. Data Direction Register B (DDRB)
DDRB6
6
0
RESET
Figure 14-8. Port B I/O Circuit
MC68HC908LB8 Data Sheet, Rev. 1
DDRB5
5
0
Table 14-2
NOTE
DDRB4
DDRBx
PTBx
4
0
summarizes the operation of the port B pins.
DDRB3
3
0
DDRB2
2
0
DDRB1
1
0
DDRB0
Bit 0
PTBx
0
Port B
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