MC68HC08GP32A Datasheet, PDF (43/258 Pages) Freescale Semiconductor, Inc – Microcontrollers

I/O Registers
3.6.1 ADC Analog Power Pin (V_DDAD)/ADC Voltage Reference High Pin (V_REFH)
The ADC analog portion uses V_DDAD as its power pin. Connect the V_DDAD pin to the same voltage
potential as V_DD. External filtering may be necessary to ensure clean V_DDAD for good results.
NOTE
For maximum noise immunity, route V_DDAD carefully and place bypass
capacitors as close as possible to the package.
3.6.2 ADC Analog Ground Pin (V_SSAD)/ADC Voltage Reference Low Pin (V_REFL)
The ADC analog portion uses V_SSAD as its ground pin. Connect the V_SSAD pin to the same voltage
potential as V_SS.
NOTE
Route V_SSAD cleanly to avoid any offset errors.
3.6.3 ADC Voltage In (V_ADIN)
V_ADIN is the input voltage signal from one of the eight 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 (ADCLK)
3.7.1 ADC Status and Control Register
Function of the ADC status and control register (ADSCR) is described here.
Address:
Read:
Write:
Reset:
$003C
Bit 7
6
5
4
3
2
1
COCO
AIEN
ADCO ADCH4 ADCH3 ADCH2 ADCH1
0
0
0
1
1
1
1
Figure 3-3. ADC Status and Control Register (ADSCR)
Bit 0
ADCH0
1
COCO — Conversions Complete
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.
In interrupt mode (AIEN = 1), COCO is a read-only bit that is not set at the end of a conversion. It
always reads as 0.
1 = Conversion completed (AIEN = 0)
0 = Conversion not completed (AIEN = 0) or CPU interrupt enabled (AIEN = 1)
NOTE
The write function of the COCO bit is reserved. When writing to the ADSCR
register, always have a 0 in the COCO bit position.
MC68HC08GP32A • MC68HC08GP16A Data Sheet, Rev. 1.0
Freescale Semiconductor
43