LM3S1G21 Datasheet, PDF (615/955 Pages) Texas Instruments – Stellaris® LM3S1G21 Microcontroller

Stellaris^® LM3S1G21 Microcontroller
Figure 13-11. Internal Temperature Sensor Characteristic
Sensor = 2.7 V – ^(T+55)
75
Sensor
2.7 V
1.633 V
0.3 V
-55° C
25° C
125° 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 (in ℃) based on the
ADC reading:
Temperature = 147.5 - ((225 × ADC) / 4095)
13.3.7
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, eight digital comparators are provided. 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. If the observed signal moves out of the
acceptable range, a processor interrupt can be generated. The digital comparators four operational
modes (Once, Always, Hysteresis Once, Hysteresis Always) can be applied to three separate regions
(low band, mid band, high band) as defined by the user.
13.3.7.1
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
digital comparator to monitor the external signal. Each comparator has two possible output functions:
processor interrupts and triggers.
January 22, 2012
615
Texas Instruments-Production Data