MC68HC908JL8 MOTOROLA [Motorola, Inc], MC68HC908JL8 Datasheet - Page 210

• Manufacturer Part Number: MC68HC908JL8
• Description: Motorola reserves the right to make changes without further notice to any products herein
• Manufacturer: MOTOROLA [Motorola, Inc]

Analog-to-Digital Converter (ADC)
12.4.2 Voltage Conversion
12.4.3 Conversion Time
12.4.4 Continuous Conversion
Technical Data
210
NOTE:
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 V
signal to $FF (full scale). If the input voltage equals V
converts it to $00. Input voltages between V
line linear conversion. All other input voltages will result in $FF if greater
than V
Input voltage should not exceed the analog supply voltages.
Fourteen ADC internal clocks are required to perform one conversion.
The ADC starts a conversion on the first rising edge of the ADC internal
clock immediately following a write to the ADSCR. If the ADC internal
clock is selected to run at 1MHz, then one conversion will take 14µs to
complete. With a 1MHz ADC internal clock the maximum sample rate is
71.43kHz.
In the continuous conversion mode, the ADC continuously converts the
selected channel filling the ADC data register 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 (ADC status and control register,
$003C) is set after each conversion and can be cleared by writing the
ADC status and control register or reading of the ADC data register.
Freescale Semiconductor, Inc.
For More Information On This Product,
Number of Bus Cycles = Conversion Time × Bus Frequency
DD
Analog-to-Digital Converter (ADC)
and $00 if less than V
Conversion Time =
Go to: www.freescale.com
SS
ADC Clock Frequency
14 ADC Clock Cycles
.
DD
DD
, the ADC converts the
and V
MC68HC908JL8
SS
SS
, the ADC
are a straight-
MOTOROLA
—
Rev. 2.0