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Analog-to-Digital Converter (ADC)
5.4.2 Voltage Conversion
NOTE:
5.4.3 Conversion Time
5.4.4 Conversion
Technical Data
90
Freescale Semiconductor, Inc.
When the input voltage to the ADC equals V
signal to $FF (full scale). If the input voltage equals V
converts it to $00. Input voltages between V
straight-line linear conversion.
Inside the ADC module, the reference voltages V
the ADC analog power, V
analog ground, V
SSAD
exceed these analog supply voltages.
Connect the V
pin to the same voltage potential as the V
DDAD
connect the V
pin to the same voltage potential as the V
SSAD
The V
pin should be routed carefully for maximum noise immunity.
DDAD
Conversion starts after a write to the ADSCR. One conversion will take
between 16 and 17 ADC clock cycles. The ADIVx and ADICLK bits
should be set to provide a 1-MHz ADC clock frequency.
Conversion time =
Number of bus cycles = conversion time × bus frequency
In continuous conversion mode, the ADC data register will be filled with
new data after each conversion. Data from the previous conversion will
be overwritten whether that data has been read or not. Conversions will
continue until the ADCO bit is cleared. The COCO bit is set after the first
conversion and will stay set until the next write of the ADC status and
control register or the next read of the ADC data register.
In single conversion mode, conversion begins with a write to the
ADSCR. Only one conversion occurs between writes to the ADSCR.
Analog-to-Digital Converter (ADC)
For More Information On This Product,
Go to: www.freescale.com
; and V
is connected to the ADC
DDAD
REFL
. Therefore, the ADC input voltage should not
16 to 17 ADC cycles
ADC frequency
MC68HC908GP32
, the ADC converts the
REFH
the ADC
REFL ,
and V
are a
REFH
REFL
is connected to
REFH
pin, and
DD
pin.
SS
MC68HC08GP32
•
—
MOTOROLA
Rev. 6
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