MC68HC908GT16_07 FREESCALE [Freescale Semiconductor, Inc], MC68HC908GT16_07 Datasheet - Page 51

• Manufacturer Part Number: MC68HC908GT16_07
• Description: Microcontrollers
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

3.3.2 ADC Port I/O Pins
PTB7/AD7–PTB0/AD0 are general-purpose I/O pins that share with the ADC channels. The channel
select bits define which ADC channel/port pin will be used as the input signal. The ADC overrides the port
I/O logic by forcing that pin as input to the ADC. The remaining ADC channels/port pins are controlled by
the port I/O logic and can be used as general-purpose I/O. Writes to the port register or data direction
register (DDR) will not have any affect on the port pin that is selected by the ADC. Read of a port pin in
use by the ADC will return a logic 0.
3.3.3 Voltage Conversion
When the input voltage to the ADC equals V
input voltage equals V
straight-line linear conversion.
Freescale Semiconductor
INTERNAL DATA BUS
The ADC input voltage must always be greater than V
V
AIEN
DDA
INTERRUPT
LOGIC
MC68HC908GT16 • MC68HC908GT8 • MC68HC08GT16 Data Sheet, Rev. 5.0
. V
COCO
READ DDRBx
WRITE DDRBx
WRITE PTBx
READ PTBx
REFL
REFH
CONVERSION
,
BUS CLOCK
COMPLETE
the ADC converts it to $00. Input voltages between V
RESET
CGMXCLK
must always be greater than or equal to V
ADIV2–ADIV0
Figure 3-2. ADC Block Diagram
ADC DATA REGISTER
GENERATOR
DDRBx
REFH
PTBx
CLOCK
ADC
ADC CLOCK
NOTE
, the ADC converts the signal to $FF (full scale). If the
ADICLK
VOLTAGE IN
(V
ADC
ADIN
V
V
REFH
REFL
DISABLE
)
DISABLE
SSA
CHANNEL
REFL
SELECT
and less than
ADC CHANNEL x
.
PTBx
ADCH4–ADCH0
REFH
Functional Description
and V
REFL
are a
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