MC68HC908JG16FA MOTOROLA [Motorola, Inc], MC68HC908JG16FA Datasheet - Page 248

• Manufacturer Part Number: MC68HC908JG16FA
• Description: Microcontrollers
• Manufacturer: MOTOROLA [Motorola, Inc]

Analog-to-Digital Converter (ADC)
13.4.1 ADC Port I/O Pins
13.4.2 Voltage Conversion
13.4.3 Conversion Time
Technical Data
248
NOTE:
NOTE:
PTA7–PTA0 are general-purpose I/O pins that are shared with the ADC
channels. The channel select bits, ADCH[4:0], in the ADC status and
control register 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 DDR will not have any affect on the port pin that is
selected by the ADC. Read of a port pin which is in use by the ADC will
return a logic 0 if the corresponding DDR bit is at logic 0. If the DDR bit
is at logic 1, the value in the port data latch is read.
When the input voltage to the ADC equals to V
the signal to $FF (full scale). If the input voltage equals to V
ADC converts it to $00. Input voltages between V
straight-line linear conversion. All other input voltages will result in $FF
if greater than V
Input voltage should not exceed the analog supply voltages.
Conversion starts after a write to the ADSCR. One conversion will take
between 16 and 17 ADC clock cycles, therefore:
For example: with a 6MHz bus clock and divide-by-4 prescaler, the ADC
clock is 1.5MHz, then one conversion will take 10.67 s to complete.
The ADC frequency must be between t
maximum to meet ADC specifications. (See
Characteristics.)
Freescale Semiconductor, Inc.
For More Information On This Product,
Number of bus cycles = conversion time
Analog-to-Digital Converter (ADC)
Go to: www.freescale.com
Conversion time =
REFH
and $00 if less than V
16 to17 ADC cycles
ADC frequency
ADIC
REFL
minimum and t
20.13 ADC Electrical
MC68HC908JG16
REFH
.
REFH
bus frequency
, the ADC converts
and V
ADIC
REFL
MOTOROLA
REFL
—
, the
Rev. 1.0
is a