MC68HC08AZ32A Datasheet, PDF (56/312 Pages) Motorola, Inc – HCMOS Microcontroller Unit

Analog-to-Digital Converter (ADC) Module
Refer to 20.7 ADC Characteristics.
Conversion Time = ¹âŽ¯⁶⎯^to⎯¹⁷⎯^A⎯^D⎯^C ⎯^Cl⎯^oc⎯^{k C}⎯^y⎯^cle⎯^s
ADC Clock Frequency
Number of Bus Cycles = Conversion Time x Bus Frequency
3.3.4 Continuous Conversion
In the 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 (ADC status and control register, $0038) is cleared. The
COCO bit is set after the first conversion and will stay set for the next several conversions until the next
write of the ADC status and control register or the next read of the ADC data register.
3.3.5 Accuracy and Precision
The conversion process is monotonic and has no missing codes. See 20.7 ADC Characteristics for
accuracy information.
3.4 Interrupts
When the AIEN bit is set, the ADC module is capable of generating a CPU interrupt after each ADC
conversion. A CPU interrupt is generated if the COCO bit (ADC status and control register, $0038) is at 0.
The COCO bit is not used as a conversion complete flag when interrupts are enabled.
3.5 Low-Power Modes
The following subsections describe the low-power modes.
3.5.1 Wait Mode
The ADC continues normal operation during wait mode. Any enabled CPU interrupt request from the ADC
can bring the MCU out of wait mode. If the ADC is not required to bring the MCU out of wait mode, power
down the ADC by setting the ADCH[4:0] bits in the ADC status and control register before executing the
WAIT instruction.
3.5.2 Stop Mode
The ADC module is inactive after the execution of a STOP instruction. Any pending conversion is aborted.
ADC conversions resume when the MCU exits stop mode. Allow one conversion cycle to stabilize the
analog circuitry before attempting a new ADC conversion after exiting stop mode.
3.6 I/O Signals
The ADC module has 15 channels that are shared with I/O ports B and D. Refer to 20.7 ADC
Characteristics for voltages referenced below.
MC68HC08AZ32A Data Sheet, Rev. 2
56
Freescale Semiconductor