Basic Operation
865
SPNU563A – March 2018
Copyright © 2018, Texas Instruments Incorporated
Analog To Digital Converter (ADC) Module
22.2.2.3 Single or Continuous Conversion Modes
The EV_MODE, G1_MODE, and G2_MODE bits are used to select between either single or continuous
conversion mode for each of the three groups.
22.2.2.3.1 Single Conversion Mode
A conversion group configured to be in single-conversion mode gets serviced only once by the ADC for
each group trigger. The trigger can be a software trigger as in the case of Group1 and Group2 by default,
or it could be a hardware event trigger as in the case of the Event Group or Group1 or Group2.
The entire conversion sequence, from the acceptance of the group conversion request to the end of the
last channel’s conversion, is flagged for each group by the corresponding BUSY bit in that group’s status
register. After single-conversion mode is started, the BUSY bit is read as 1 until the conversion of the last
channel is complete. The END bit for the group is set once all the channels in that group are converted.
For example, say channels 0, 2, 4, and 6 are selected for conversion in Group1 in single-conversion
mode. When the Group1 gets serviced, the ADC will start conversion for channel 0, then channel 2, then
channel 4, and then channel 6. It will then stop servicing the Group1, set the GP1_END status bit, and
look to service the Event Group or the Group2, if required.
22.2.2.3.2 Continuous Conversion Mode
A conversion group configured to be in continuous-conversion mode gets serviced by the ADC
continuously. The group still needs to be triggered appropriately for the first conversion to start. The
conversions are performed continuously thereafter.
The entire conversion sequence, from the acceptance of the group conversion request to the end of the
last channel’s conversion, is flagged for each group by the corresponding BUSY bit in that group’s status
register. After continuous-conversion mode is started, the BUSY bit is read as 1 as long as the
continuous-conversion mode for this group is selected.
As an example, say the channels 0, 2, 4, and 6 are selected for conversion in Group1, now in continuous-
conversion mode. When the Group1 gets serviced, the ADC will complete conversions for channels 0, 2, 4
and 6, and then look to service the Event Group or the Group2. Once it is done servicing the Event Group
or the Group2, it will return to service the Group1 again. The Group1 does not need to be triggered again
for the repeated conversion.
NOTE:
Configuring all conversion groups in continuous conversion mode
All the three groups cannot operate in continuous-conversion mode at the same time. If the
application program configures all three groups to be in continuous-conversion mode, the
Group2 is automatically reset to single-conversion mode, and the G2 MODE bit in the
ADG2MODECR register is cleared to reflect the single-conversion mode of Group2.
22.2.2.4 Conversion Group Freeze Capability
The ADC module has an inherent priority order between the three conversion groups. This group priority
determines the order of conversion in case multiple groups are triggered. The priority of conversions
between the three groups in descending order is:
1. Event Group
2. Group1
3. Group2