MC68HC08AZ32A Datasheet, PDF (57/312 Pages) Motorola, Inc – HCMOS Microcontroller Unit

I/O Registers
3.6.1 ADC Analog Power Pin (V_DDAREF)
The ADC analog portion uses V_DDAREF as its power pin. Connect the V_DDAREF pin to the same voltage
potential as V_DD. External filtering may be necessary to ensure clean V_DDAREF for good results.
NOTE
Route V_DDAREF carefully for maximum noise immunity and place bypass
capacitors as close as possible to the package. V_DDAREF must be present
for operation of the ADC.
3.6.2 ADC Analog Ground/ADC Voltage Reference Low Pin (AV_SS/V_REFL)
The ADC analog portion uses AV_SS/V_REFL as its ground pin. Connect the AV_SS/V_REFL pin to the same
voltage potential as V_SS.
V_REFL is the lower reference supply for the ADC.
3.6.3 ADC Voltage Reference Pin (V_REFH)
V_REFH is the high reference voltage for all analog-to-digital conversions.
3.6.4 ADC Voltage In (ADCVIN)
ADCVIN is the input voltage signal from one of the 15 ADC channels to the ADC module.
3.7 I/O Registers
These I/O registers control and monitor ADC operation:
• ADC status and control register (ADSCR)
• ADC data register (ADR)
• ADC clock register (ADICLK)
3.7.1 ADC Status and Control Register
The following paragraphs describe the function of the ADC status and control register.
Address:
Read:
Write:
Reset:
$0038
Bit 7
COCO
R
0
R
6
5
AIEN
ADCO
0
0
= Unimplemented
4
ADCH4
1
3
ADCH3
1
2
ADCH2
1
1
ADCH1
1
Figure 3-3. ADC Status and Control Register (ADSCR)
Bit 0
ADCH0
1
COCO — Conversions Complete Bit
In non-interrupt mode (AIEN = 0), COCO is a read-only bit that is set at the end of each conversion.
COCO will stay set until cleared by a read of the ADC data register. Reset clears this bit.
MC68HC08AZ32A Data Sheet, Rev. 2
Freescale Semiconductor
57