Datasheet

Chapter 13 Analog-to-Digital Converter (ADC12B16CV1)
MC9S12XE-Family Reference Manual Rev. 1.25
510 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 13-6.
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