Datasheet

Channel 0
SD24SNGL = 1
SD24GRP = 1
Time
Conversion
SD24SC
Channel 1
SD24SNGL = 0
SD24GRP = 1
Conversion
Channel 2
SD24SNGL = 0
SD24GRP = 0
Conversion
SD24SC
SD24SC
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 SD24MEMx
www.ti.com SD24_A Operation
27.2.9.3 Group of Channels, Single Conversion
Consecutive SD24_A channels can be grouped together with the SD24GRP bit to synchronize
conversions. Setting SD24GRP for a channel groups that channel with the next channel in the module.
For example, setting SD24GRP for channel 0 groups that channel with channel 1. In this case, channel 1
is the master channel, enabling and disabling conversion of all channels in the group with its SD24SC bit.
The SD24GRP bit of the master channel is always 0. The SD24GRP bit of last channel in SD24_A has no
function and is always 0.
When SD24SNGL = 1 for a channel in a group, single conversion mode is selected. A single conversion of
that channel will occur synchronously when the master channel SD24SC bit is set. The SD24SC bit of all
channels in the group will automatically be set and cleared by SD24SC of the master channel. SD24SC
for each channel can also be cleared in software independently.
Clearing SD24SC of the master channel before the conversions are completed immediately stops
conversions of all channels in the group, the channels are powered down and the corresponding digital
filters are turned off. Values in SD24MEMx can change when SD24SC is cleared. It is recommended that
the conversion data in SD24MEMx be read prior to clearing SD24SC to avoid reading an invalid result.
27.2.9.4 Group of Channels, Continuous Conversion
When SD24SNGL = 0 for a channel in a group, continuous conversion mode is selected. Continuous
conversion of that channel will occur synchronously when the master channel SD24SC bit is set. SD24SC
bits for all grouped channels will be automatically set and cleared with the master channel's SD24SC bit.
SD24SC for each channel in the group can also be cleared in software independently.
When SD24SC 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 SD24SC 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 SD24MEMx can
change when SD24SC is cleared. It is recommended that the conversion data in SD24MEMx be read prior
to clearing SD24SC to avoid reading an invalid result.
Figure 27-8 shows grouped channel operation for three SD24_A channels. Channel 0 is configured for
single conversion mode, SD24SNGL = 1, and channels 1 and 2 are in continuous conversion mode,
SD24SNGL = 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 SD24SC bit is
set using software.
Figure 27-8. Grouped Channel Operation - Example
627
SLAU144J–December 2004–Revised July 2013 SD24_A
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