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R01UH0336EJ0102 Rev.1.02
Page 1279 of 1538
Jul 17, 2014
V850E2/PG4-L
Section 23 A/D Converter
23.3.3
Channel and Channel Group
Input channels are grouped into channel groups (CG). The scan list for each
CG can be set in a register and reconfigured during A/D conversion. The
conversion settings for a CG are applied to all the channels of the CG.
The ADCAn supports up to 3 channel groups CGi (i = 0 to 2). The channels of
CGi are specified in ADCAnCGi.
Note
The ADCAn processes A/D conversion requests for CGs only. To convert a
single channel, only 1 channel must be assigned to a CG.
(1)
Order of A/D Conversion
If a trigger for a CG occurs, the channels of the CG are converted one by one
in ascending order (from CH01 to CH18).
If A/D conversion requests for multiple CGs are pending, the CGs are
converted in the following hierarchical order:
CG2 (highest priority) > CG1 > CG0 (lowest priority)
The current A/D conversion is interrupted when a start trigger for a higher-
priority CG is set. Depending on the setting in ADCAnCTL1.ADCAnTRMi,
there are 2 options:
• The A/D conversion of CG is interrupted immediately
(ADCAnCTL1.ADCAnTRMi = 0).
After the A/D conversions of all the higher-priority CGs are finished, the A/D
conversion of the interrupted channel is resumed.
• The A/D conversion of the current channel is completed before the higher-
priority CG is converted (ADCAnCTL1.ADCAnTRMi = 1).
After the A/D conversions of all the higher-priority CGs are finished, the
interrupted A/D conversion is resumed from the next channel.
ADCAnSTR2.ADCAnST[2:0] indicates the current conversion status of all the
CGs.
Examples
The following figures illustrate the different types of A/D conversion
interruption;
CH3, CH9, and CH20 are assigned to CG0, CH5 and CH9 are assigned to
CG2.
Figure 23-2
When A/D Conversion of CG0 is Immediately Interrupted
(ADCAnCTL1.ADCAnTRM0 = 0)
Status
Conversion of CG0
Idle
CG0 CH3
Convert
Convert
CG2 CH5
CG0 CH9
Sample
Sample
Convert
Convert
Sample
Sample
Convert
Convert
Sample
Sample
CG2 CH9
CG0 CH9
Conversion of CG2
CG0 CH20
Conversion of CG0
Idle
CG0 = CH3, CH9, CH20
CG2 = CH5, CH9
Start trigger
CG0
Start trigger
CG2