8.2 SOC Principle of Operation
Contrary to previous ADC types, this ADC is not sequencer based. Instead, it is SOC based. The term SOC is
configuration set defining the single conversion of a single channel. In that set there are three configurations: the
trigger source that starts the conversion, the channel to convert, and the acquisition (sample) window size. Each
SOC is independently configured and can have any combination of the trigger, channel, and sample window size
available. Multiple SOCs can be configured for the same trigger, channel, and/or acquisition window as desired.
This provides a very flexible means of configuring conversions ranging from individual samples of different
channels with different triggers, to oversampling the same channel using a single trigger, to creating your own
series of conversions of different channels all from a single trigger.
The trigger source for SOCx is configured by a combination of the TRIGSEL field in the ADCSOCxCTL register
and the appropriate bits in the ADCINTSOCSEL1 or ADCINTSOCSEL2 register. Software can also force an
SOC event with the ADCSOCFRC1 register. The channel and sample window size for SOCx are configured with
the CHSEL and ACQPS fields of the ADCSOCxCTL register.
SOC15
SOC2
SOC1
ADC Sample
Generation
Logic
ADCSOC2CTL.ACQPS
A
C
Q
P
S
C
H
S
E
L
S
O
C
SOC0
ADCSOCFRC1.SOC0
0
1
12
2
ADCTRIG1
ADCTRIG2
ADCTRIG12
0
1
2
3
ADCINT1
ADCINT2
undefined
ADCSOC2CTL.CHSEL
ADCSOC0CTL.CHSEL
Latch
Set
Clear
SOCOVF
ADCSOCFLG1.SOC0
ADCSOC15CTL.ACQPS
ADCSOC0CTL.ACQPS
ADCSOC0CTL.CHSEL
ADCSOCFLG1.SOC2
ADCSOCFLG1.SOC15
ADCSOC15CTL.CHSEL
Start of SOC0
ADCSOC0CTL.TRIGSEL
ADCINTSOCSEL1.SOC0
ADCSOC1CTL.ACQPS
ADCSOC0CTL.ACQPS
ADCSOC1CTL.CHSEL
ADCSOCFLG1.SOC1
Figure 8-2. SOC Block Diagram
For example, to configure a single conversion on channel ADCINA1 to occur when the ePWM3 timer reaches its
period match, you must first setup ePWM3 to output an SOCA or SOCB signal on a period match (see
). In this case, we will use SOCA. Then, set up one of the SOCs using its ADCSOCxCTL register. It makes no
difference which SOC we choose, so we will use SOC0. The fastest allowable sample window for the ADC is
7 cycles. Choosing the fastest time for the sample window, channel ADCINA1 for the channel to convert, and
ePWM3 for the SOC0 trigger, we’ll set the ACQPS field to 6, the CHSEL field to 1, and the TRIGSEL field to 9,
respectively. The resulting value written into the register is:
ADCSOC0CTL = 4846h;
// (ACQPS=6, CHSEL=1, TRIGSEL=9)
When configured as such, a single conversion of ADCINA1 will be started on an ePWM3 SOCA event with the
resulting value stored in the ADCRESULT0 register.
Analog-to-Digital Converter (ADC)
SPRUH18I – JANUARY 2011 – REVISED JUNE 2022
TMS320x2806x Microcontrollers
513
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Summary of Contents for TMS320 2806 Series
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