LM3S5G31 Datasheet, PDF (638/1223 Pages) Texas Instruments – Stellaris LM3S5G31 Microcontroller

Analog-to-Digital Converter (ADC)
13.3.7.3
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 or equal to COMP0), mid-band (greater than COMP0
but less than or equal to COMP1), and high-band (greater than 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.
Low-Band Operation
To operate in the low-band region, either 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 Figure
13-15 on page 638. 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 de-asserted
and a "1" indicates that the signal is asserted.
Figure 13-15. Low-Band Operation (CIC=0x0 and/or CTC=0x0)
COMP1
COMP0
Always – 0 0 0 0 1 1 1 0 0 1 1 0 0 0 0 1
Once – 0 0 0 0 1 0 0 0 0 1 0 0 0 0 0 1
Hysteresis Always – 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 1
Hysteresis Once – 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 1
Mid-Band Operation
To operate in the mid-band region, either the CIC field or the CTC field in the ADCDCCTLn register
must be programmed to 0x1. This setting causes interrupts or triggers to be generated in the mid-band
region according the operation mode. Only the Always and Once operational modes are available
in the mid-band region. An example of the state of the interrupt/trigger signal in the mid-band region
for each of the allowed operational modes is shown in Figure 13-16 on page 639. Note that a "0" in
638
July 03, 2014
Texas Instruments-Production Data