s908qc16vdse Freescale Semiconductor, Inc, s908qc16vdse Datasheet - Page 52

• Manufacturer Part Number: s908qc16vdse
• Description: M68hc08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Analog-to-Digital Converter (ADC10) Module
3.4 Interrupts
When AIEN is set, the ADC10 is capable of generating an interrupt request after each conversion. An
interrupt request is generated when the conversion completes (indicated by COCO being set). COCO will
set at the end of a conversion regardless of the state of AIEN.
3.5 Low-Power Modes
The WAIT and STOP instructions put the MCU in low power-consumption standby modes.
3.5.1 Wait Mode
The ADC10 will continue the conversion process and will generate an interrupt request following a
conversion if AIEN is set. If the ADC10 is not required in wait mode, power down the ADC by setting the
channel select bits (ADCH[4:0]) to all 1s to enter a low power state before executing the WAIT instruction.
3.5.2 Stop Mode
If ACLKEN is clear, executing a STOP instruction will abort the current conversion and place the ADC10
in a low-power state. Upon return from stop mode, a write to ADSCR is required to resume conversions,
and the result stored in ADRH and ADRL will represent the last completed conversion until the new
conversion completes.
If ACLKEN is set, the ADC10 continues normal operation during stop mode. The ADC10 will continue the
conversion process and will generate an interrupt following a conversion if AIEN is set. If the ADC10 is
not required to bring the MCU out of stop mode, ensure that the ADC10 is not in continuous conversion
mode by clearing ADCO in the ADC10 status and control register before executing the STOP instruction.
In single conversion mode the ADC10 automatically enters a low-power state when the conversion is
complete. It is not necessary to set the channel select bits (ADCH[4:0]) to all 1s to enter a low-power state.
If ACLKEN is set, a conversion can be initiated while in stop using the external hardware trigger
ADEXTCO when in external convert mode. The ADC10 will operate in a low-power mode until the trigger
is asserted, at which point it will perform a conversion and assert the interrupt when complete (if AIEN is
set).
3.6 ADC10 During Break Interrupts
The system integration module (SIM) controls whether status bits in other modules can be cleared during
the break state. BCFE in the break flag control register (BFCR) enables software to clear status bits
during the break state. See BFCR in the SIM section of this data
sheet.
To allow software to clear status bits during a break interrupt, write a 1 to BCFE. If a status bit is cleared
during the break state, it remains cleared when the MCU exits the break state.
To protect status bits during the break state, write a 0 to BCFE. With BCFE cleared (its default state),
software can read and write registers during the break state without affecting status bits. Some status bits
have a two-step read/write clearing procedure. If software does the first step on such a bit before the
break, the bit cannot change during the break state as long as BCFE is cleared. After the break, doing
the second step clears the status bit.
MC68HC908QC16 • MC68HC908QC8 • MC68HC908QC4 Data Sheet, Rev. 4
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Freescale Semiconductor