MC908MR16CFUE Datasheet, PDF(50/282 Page) Freescale Semiconductor, Inc – On-chip programming firmware for use with host personal computer, Clock generator module (CGM)

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MC908MR16CFUE Datasheet, PDF (50/282 Pages) Freescale Semiconductor, Inc – On-chip programming firmware for use with host personal computer, Clock generator module (CGM)

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Analog-to-Digital Converter (ADC)

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 is at 0. The COCO bit is not used as a

conversion complete flag when interrupts are enabled.

3.5 Wait Mode

The WAIT instruction can put the MCU in low power-consumption standby 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 ADCH[4:0] in the ADC status and control register before executing the WAIT

instruction.

3.6 I/O Signals

The ADC module has 10 input signals that are shared with port B and port C.

3.6.1 ADC Analog Power Pin (VDDAD)

The ADC analog portion uses VDDAD as its power pin. Connect the VDDAD pin to the same voltage

potential as VDD. External filtering may be necessary to ensure clean VDDAD for good results.

NOTE

Route VDDAD carefully for maximum noise immunity and place bypass

capacitors as close as possible to the package.

3.6.2 ADC Analog Ground Pin (VSSAD)

The ADC analog portion uses VSSAD as its ground pin. Connect the VSSAD pin to the same voltage

potential as VSS.

3.6.3 ADC Voltage Reference Pin (VREFH)

VREFH is the power supply for setting the reference voltage VREFH. Connect the VREFH pin to the same

voltage potential as VDDAD. There will be a finite current associated with VREFH. See Chapter 19 Electrical

Specifications.

NOTE

Route VREFH carefully for maximum noise immunity and place bypass

capacitors as close as possible to the package.

3.6.4 ADC Voltage Reference Low Pin (VREFL)

VREFL is the lower reference supply for the ADC. Connect the VREFL pin to the same voltage potential as

VSSAD. A finite current will be associated with VREFL. See Chapter 19 Electrical Specifications.

NOTE

In the 56-pin shrink dual in-line package (SDIP), VREFL and VSSAD are tied

together.

MC68HC908MR32 â¢ MC68HC908MR16 Data Sheet, Rev. 6.1

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Freescale Semiconductor

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