mc68hc908mr32 Freescale Semiconductor, Inc, mc68hc908mr32 Datasheet - Page 47

• Manufacturer Part Number: mc68hc908mr32
• Description: M68hc08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

3.3.1 ADC Port I/O Pins
PTC1/ATD9:PTC0/ATD8 and PTB7/ATD7:PTB0/ATD0 are general-purpose I/O pins that are shared 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 logic when that port is selected by the ADC multiplexer. The remaining ADC
channels/port pins are controlled by the port logic and can be used as general-purpose input/output (I/O)
pins. Writes to the port register or DDR will not have any effect 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 0.
3.3.2 Voltage Conversion
When the input voltage to the ADC equals V
input voltage equals V
straight-line linear conversions. All other input voltages will result in $3FF if greater than V
if less than V
Freescale Semiconductor
INTERNAL
DATA BUS
REFL
AIEN
Input voltage should not exceed the analog supply voltages. See
19.13 Analog-to-Digital Converter (ADC)
INTERRUPT
LOGIC
.
READ PTB/PTC
COCO
REFL
BUS CLOCK
CONVERSION
MC68HC908MR32 • MC68HC908MR16 Data Sheet, Rev. 6.1
CGMXCLK
COMPLETE
, the ADC converts it to $000. Input voltages between V
Figure 3-2. ADC Block Diagram
ADIV[2:0]
ADC DATA REGISTERS
GENERATOR
REFH
CLOCK
ADC
ADC CLOCK
, the ADC converts the signal to $3FF (full scale). If the
NOTE
ADICLK
Characteristics.
ADC VOLTAGE IN
ADVIN
DISABLE
CHANNEL
SELECT
ADC CHANNEL x
REFH
PTB/Cx
Functional Description
and V
REFH
ADCH[4:0]
REFL
and $000
are
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