Chapter 13 Analog-to-Digital Converter (ADC12B16CV1)
MC9S12XE-Family Reference Manual , Rev. 1.19
508
Freescale Semiconductor
4
SMP_DIS
Discharge Before Sampling Bit
0 No discharge before sampling.
1 The internal sample capacitor is discharged before sampling the channel. This adds 2 ATD clock cycles to
the sampling time. This can help to detect an open circuit instead of measuring the previous sampled
channel.
3–0
ETRIGCH[3:0]
External Trigger Channel Select
— These bits select one of the AD channels or one of the ETRIG3-0 inputs
as source for the external trigger. The coding is summarized in
Table 13-5. A/D Resolution Coding
SRES1
SRES0
A/D Resolution
0
0
8-bit data
0
1
10-bit data
1
0
12-bit data
1
1
Reserved
Table 13-6. External Trigger Channel Select Coding
ETRIGSEL
ETRIGCH3
ETRIGCH2
ETRIGCH1
ETRIGCH0
External trigger source is
0
0
0
0
0
AN0
0
0
0
0
1
AN1
0
0
0
1
0
AN2
0
0
0
1
1
AN3
0
0
1
0
0
AN4
0
0
1
0
1
AN5
0
0
1
1
0
AN6
0
0
1
1
1
AN7
0
1
0
0
0
AN8
0
1
0
0
1
AN9
0
1
0
1
0
AN10
0
1
0
1
1
AN11
0
1
1
0
0
AN12
0
1
1
0
1
AN13
0
1
1
1
0
AN14
0
1
1
1
1
AN15
1
0
0
0
0
ETRIG0
(1)
1. Only if ETRIG3-0 input option is available (see device specification), else ETRISEL is ignored, that means
external trigger source is still on one of the AD channels selected by ETRIGCH3-0
1
0
0
0
1
ETRIG1
1
1
0
0
1
0
ETRIG2
1
1
0
0
1
1
ETRIG3
1
1
0
1
X
X
Reserved
1
1
X
X
X
Reserved
Table 13-4. ATDCTL1 Field Descriptions (continued)
Field
Description
Because
of
an
order
from
the
United
States
International
Trade
Commission,
BGA-packaged
product
lines
and
part
numbers
indicated
here
currently
are
not
available
from
Freescale
for
import
or
sale
in
the
United
States
prior
to
September
2010:
S12XE
products
in
208
MAPBGA
packages