MC68HC908GR4 MOTOROLA [Motorola, Inc], MC68HC908GR4 Datasheet - Page 213

• Manufacturer Part Number: MC68HC908GR4
• Description: Microcontrollers
• Manufacturer: MOTOROLA [Motorola, Inc]

16.4 Port B
16.4.1 Port B Data Register
MC68HC908GR8 — Rev 4.0
MOTOROLA
NOTE:
NOTE:
Function:
Alternate
Address:
Port B is an 6-bit special-function port that shares all six of its pins with
the analog-to-digital converter (ADC) module.
The port B data register (PTB) contains a data latch for each of the six
port pins.
PTB5–PTB0 — Port B Data Bits
AD5–AD0 — Analog-to-Digital Input Bits
Care must be taken when reading port B while applying analog voltages
to AD5–AD0 pins. If the appropriate ADC channel is not enabled,
excessive current drain may occur if analog voltages are applied to the
PTBx/ADx pin, while PTB is read as a digital input. Those ports not
selected as analog input channels are considered digital I/O ports.
PTB4 and 5 are not available in a 28-pin DIP and SOIC package
Reset:
Read:
Write:
Freescale Semiconductor, Inc.
These read/write bits are software-programmable. Data direction of
each port B pin is under the control of the corresponding bit in data
direction register B. Reset has no effect on port B data.
AD5–AD0 are pins used for the input channels to the analog-to-digital
converter module. The channel select bits in the ADC status and
control register define which port B pin will be used as an ADC input
and overrides any control from the port I/O logic by forcing that pin as
the input to the analog circuitry.
For More Information On This Product,
$0001
Bit 7
0
Go to: www.freescale.com
Figure 16-6. Port B Data Register (PTB)
Input/Output Ports (I/O)
6
0
PTB5
AD5
5
Unaffected by reset
PTB4
AD4
4
PTB3
AD3
3
PTB2
AD2
2
Input/Output Ports (I/O)
PTB1
AD1
1
Technical Data
PTB0
Bit 0
AD0
Port B
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