Analog-to-Digital Converter (ADC)
MC68HC908GT16 MC68HC908GT8 MC68HC08GT16 Data Sheet, Rev. 5.0
54
Freescale Semiconductor
3.6.5 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.
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.
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 a 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.
AIEN — ADC Interrupt Enable Bit
When this bit is set, an interrupt is generated at the end of an ADC conversion. The interrupt signal is
cleared when the data register is read or the status/control register is written. Reset clears the AIEN bit.
1 = ADC interrupt enabled
0 = ADC interrupt disabled
ADCO — ADC Continuous Conversion Bit
When set, the ADC will convert samples continuously and update the ADR register at the end of each
conversion. Only one conversion is completed between writes to the ADSCR when this bit is cleared.
Reset clears the ADCO bit.
1 = Continuous ADC conversion
0 = One ADC conversion
Address:
$003C
Bit 7
COCO
R
0
R
6
5
4
3
2
1
Bit 0
Read:
Write:
Reset:
AIEN
ADCO
ADCH4
ADCH3
ADCH2
ADCH1
ADCH0
0
0
1
1
1
1
1
= Reserved
Figure 3-3. ADC Status and Control Register (ADSCR)