MC9S12P128 Datasheet, PDF (316/564 Pages) Freescale Semiconductor, Inc – S12 Microcontrollers

Analog-to-Digital Converter (ADC12B10CRev 00.05) Block Description
9.3.2.6 ATD Control Register 5 (ATDCTL5)
Writes to this register will abort current conversion sequence and start a new conversion sequence. If
external trigger is enabled (ETRIGE=1) an initial write to ATDCTL5 is required to allow starting of a
conversion sequence which will then occur on each trigger event. Start of conversion means the beginning
of the sampling phase.
Module Base + 0x0005
7
R
0
W
6
5
4
3
2
1
0
SC
SCAN
MULT
CD
CC
CB
CA
Reset
0
0
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 9-8. ATD Control Register 5 (ATDCTL5)
Read: Anytime
Write: Anytime
Table 9-14. ATDCTL5 Field Descriptions
Field
6
SC
5
SCAN
4
MULT
3–0
CD, CC,
CB, CA
Description
Special Channel Conversion Bit — If this bit is set, then special channel conversion can be selected using CD,
CC, CB and CA of ATDCTL5. Table 9-15 lists the coding.
0 Special channel conversions disabled
1 Special channel conversions enabled
Continuous Conversion Sequence Mode — This bit selects whether conversion sequences are performed
continuously or only once. If external trigger is enabled (ETRIGE=1) setting this bit has no effect, that means
external trigger always starts a single conversion sequence.
0 Single conversion sequence
1 Continuous conversion sequences (scan mode)
Multi-Channel Sample Mode — When MULT is 0, the ATD sequence controller samples only from the specified
analog input channel for an entire conversion sequence. The analog channel is selected by channel selection
code (control bits CD/CC/CB/CA located in ATDCTL5). When MULT is 1, the ATD sequence controller samples
across channels. The number of channels sampled is determined by the sequence length value (S8C, S4C, S2C,
S1C). The first analog channel examined is determined by channel selection code (CD, CC, CB, CA control bits);
subsequent channels sampled in the sequence are determined by incrementing the channel selection code or
wrapping around to AN0 (channel 0).
0 Sample only one channel
1 Sample across several channels
Analog Input Channel Select Code — These bits select the analog input channel(s) whose signals are
sampled and converted to digital codes. Table 9-15 lists the coding used to select the various analog input
channels.
In the case of single channel conversions (MULT=0), this selection code specifies the channel to be examined.
In the case of multiple channel conversions (MULT=1), this selection code specifies the first channel to be
examined in the conversion sequence. Subsequent channels are determined by incrementing the channel
selection code or wrapping around to AN0 (after converting the channel defined by the Wrap Around Channel
Select Bits WRAP3-0 in ATDCTL0). In case of starting with a channel number higher than the one defined by
WRAP3-0 the first wrap around will be AN9 to AN0.
S12P-Family Reference Manual, Rev. 1.12
316
Freescale Semiconductor