Advanced Conversion Group Configuration Options
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SPNU503C – March 2018
Copyright © 2018, Texas Instruments Incorporated
Analog To Digital Converter (ADC) Module
19.4.1 Group Trigger Options
The Group1 and Group2 operating mode control registers have an extra control bit: HW TRIG. This bit
configures the group to be hardware event-triggered instead of software-triggered, which is the default.
When a group is configured to be event-triggered, the group conversion starts when at least one channel
is selected for conversion in this group, and when the defined event trigger occurs. The event trigger
source is defined for each group in the ADEVSRC, ADG1SRC, and the ADG2SRC registers. The actual
connections used as the event trigger sources are defined in the device datasheet for both the ADC
modules.
19.4.2 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.
19.4.2.1 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 G1_END status bit, and look
to service the Event Group or the Group2, if required.
19.4.2.2 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.