Texas Instruments MSP430x4xx - Manual (Page 415)

SD16 Operation
21-12 SD16
Group of Channels, Continuous Conversion
When SD16SNGL = 0 for a channel in a group, continuous conversion mode
is selected. Continuous conversion of that channel will occur synchronously
when the master channel SD16SC bit is set. SD16SC bits for all grouped
channels will be automatically set and cleared with the master channel’s
SD16SC bit. SD16SC for each channel in the group can also be cleared in
software independently.
When SD16SC of a grouped channel is set by software independently of the
master, conversion of that channel will automatically synchronize to
conversions of the master channel. This ensures that conversions for grouped
channels are always synchronous to the master.
Clearing SD16SC of the master channel immediately stops conversions of all
channels in the group the channels are powered down and the corresponding
digital filters are turned off. Values in SD16MEMx can change when SD16SC
is cleared. It is recommended that the conversion data in SD16MEMx be read
prior to clearing SD16SC to avoid reading an invalid result.
Figure 21−7 shows grouped channel operation for three SD16 channels.
Channel 0 is configured for single conversion mode, SD16SNGL = 1, and
channels 1 and 2 are in continuous conversion mode, SD16SNGL = 0.
Channel two, the last channel in the group, is the master channel. Conversions
of all channels in the group occur synchronously to the master channel
regardless of when each SD16SC bit is set using software.
Figure 21−7. Grouped Channel Operation
Channel 0
SD16SNGL = 1
SD16GRP = 1
Time
Conversion
SD16SC
Channel 1
SD16SNGL = 0
SD16GRP =1
Conversion
Channel 2
SD16SNGL = 0
SD16GRP = 0
Conversion
SD16SC
SD16SC
Conversion Conversion
Set by Ch2 Auto−clear
Set by Ch2
Conv
Set by SW Cleared by SW
Conversion Conv
Cleared by Ch2
Set by SW Auto−clear
Conversion
(syncronized to master)
Cleared by SW
Conv
Set by SW
(syncronized to master)
= Result written to SD16MEMx