Functional Description
715
SLAU723A – October 2017 – Revised October 2018
Copyright © 2017–2018, Texas Instruments Incorporated
Analog-to-Digital Converter (ADC)
10.3.7.2 Operational Modes
Four operational modes are provided to support a broad range of applications and multiple possible
signaling requirements: Always, Once, Hysteresis Always, and Hysteresis Once. The operational mode is
selected using the CIM or CTM field in the ADCDCCTLn register.
10.3.7.2.1 Always Mode
In the Always operational mode, the associated interrupt or trigger is asserted whenever the ADC
conversion value meets its comparison criteria. The result is a string of assertions on the interrupt or
trigger while the conversions are within the appropriate range.
10.3.7.2.2 Once Mode
In the Once operational mode, the associated interrupt or trigger is asserted whenever the ADC
conversion value meets its comparison criteria, and the previous ADC conversion value did not. The result
is a single assertion of the interrupt or trigger when the conversions are within the appropriate range.
10.3.7.2.3 Hysteresis-Always Mode
The Hysteresis-Always operational mode can only be used in conjunction with the low-band or high-band
regions because the mid-band region must be crossed and the opposite region entered to clear the
hysteresis condition. In the Hysteresis-Always mode, the associated interrupt or trigger is asserted in the
following cases: 1) the ADC conversion value meets its comparison criteria or 2) a previous ADC
conversion value has met the comparison criteria, and the hysteresis condition has not been cleared by
entering the opposite region. The result is a string of assertions on the interrupt or trigger that continue
until the opposite region is entered.
10.3.7.2.4 Hysteresis-Once Mode
The Hysteresis-Once operational mode can only be used in conjunction with the low-band or high-band
regions because the mid-band region must be crossed and the opposite region entered to clear the
hysteresis condition. In the Hysteresis-Once mode, the associated interrupt or trigger is asserted only
when the ADC conversion value meets its comparison criteria, the hysteresis condition is clear, and the
previous ADC conversion did not meet the comparison criteria. The result is a single assertion on the
interrupt or trigger.
10.3.7.3 Function Ranges
The two comparison values, COMP0 and COMP1, in the ADC Digital Comparator Range (ADCDCCMPn)
register effectively break the conversion area into three distinct regions. These regions are referred to as
the low-band (less than COMP0), mid-band (greater than COMP0 but less than or equal to COMP1), and
high-band (greater than or equal to COMP1) regions. COMP0 and COMP1 may be programmed to the
same value, effectively creating two regions, but COMP1 must always be greater than or equal to the
value of COMP0. A COMP1 value that is less than COMP0 generates unpredictable results.
10.3.7.3.1 Low-Band Operation
To operate in the low-band region, the CIC field or the CTC field in the ADCDCCTLn register must be
programmed to 0x0. This setting causes interrupts or triggers to be generated in the low-band region as
defined by the programmed operational mode. An example of the state of the interrupt/trigger signal in the
low-band region for each of the operational modes is shown in
. Note that a 0 in a column
following the operational mode name (Always, Once, Hysteresis Always, and Hysteresis Once) indicates
that the interrupt or trigger signal is deasserted and a 1 indicates that the signal is asserted.