LM4F111C4QR Datasheet, PDF (742/1113 Pages) Texas Instruments – Microcontroller

Analog-to-Digital Converter (ADC)
Figure 12-11. Internal Temperature Sensor Characteristic
V_TSENS = 2.7 V – ^(TEMP+55)
75
V_TSENS
2.5 V
1.633 V
0.833 V
-40° C
25° C
85° C Temp
The temperature sensor reading can be sampled in a sample sequence by setting the TSn bit in
the ADCSSCTLn register. The temperature reading from the temperature sensor can also be given
as a function of the ADC value. The following formula calculates temperature (TEMP in ℃) based
on the ADC reading (ADC_CODE, given as an unsigned decimal number from 0 to 4095) and the
maximum ADC voltage range (VREFP - VREFN):
TEMP = 147.5 - ((75 * (VREFP - VREFN) × ADC_CODE) / 4096)
12.3.7
Digital Comparator Unit
An ADC is commonly used to sample an external signal and to monitor its value to ensure that it
remains in a given range. To automate this monitoring procedure and reduce the amount of processor
overhead that is required, each module provides eight digital comparators.
Conversions from the ADC that are sent to the digital comparators are compared against the user
programmable limits in the ADC Digital Comparator Range (ADCDCCMPn) registers. The ADC
can be configured to generate an interrupt depending on whether the ADC is operating within the
low, mid or high-band region configured in the ADCDCCMPn bit fields. The digital comparators four
operational modes (Once, Always, Hysteresis Once, Hysteresis Always) can be additionally applied
to the interrupt configuration.
12.3.7.1
Output Functions
ADC conversions can either be stored in the ADC Sample Sequence FIFOs or compared using the
digital comparator resources as defined by the SnDCOP bits in the ADC Sample Sequence n
Operation (ADCSSOPn) register. These selected ADC conversions are used by their respective
742
April 25, 2012
Texas Instruments-Advance Information