Analog-to-Digital Converter (ADC)
Data Sheet
MC68HC908QF4 — Rev. 1.0
42
Analog-to-Digital Converter (ADC)
MOTOROLA
3.7.1 ADC Status and Control Register
The following paragraphs describe the function of the ADC status and control
register (ADSCR). When a conversion is in process and the ADSCR is written, the
current conversion data should be discarded to prevent an incorrect reading.
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 ADR is read or ADSCR 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 ADR at the
end of each conversion. Only one conversion is allowed when this bit is cleared.
Reset clears the ADCO bit.
1 = Continuous ADC conversion
0 = One ADC conversion
CH[4:0] — ADC Channel Select Bits
CH4, CH3, CH2, CH1, and CH0 form a 5-bit field which is used to select one of
the four ADC channels. The five select bits are detailed in Table 3-1. Care
Address: $003C
Bit 7
654321
Bit 0
Read:
COCO
AIEN
ADCO
CH4
CH3
CH2
CH1
CH0
Write:
Reset:
00011111
= Unimplemented
Figure 3-4. ADC Status and Control Register (ADSCR)
F
re
e
sc
a
le
S
e
m
ic
o
n
d
u
c
to
r,
I
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
n
c
..
.