|
Kategorie: Diplomové, bakalářské práce |
Tento dokument chci!
Práce popisuje principy a problémy při realizaci ultrazvukového anemometru. Je popsán princip výpočtu rychlosti větru a následné korekce výpočtu. Pro realizaci jsou využity ultrazvukové sensory a microcontrolér ARM Cortex-M3. Práce se zabývá generováním PWM signálu, jeho analogovou filtrací, zesílením a odvysíláním. Na přijímací straně jeto nízkonapěťový zesilovač a komparátor. Vyvíjený kód je popsán pomocí vývojového diagramu.
For purposes our application, NTC thermistor Vishay was used. The resistance increase with increasing
temperature and temperature coefficient positive.
● NTC Negative temperature coefficient.
Illustration 2. Thermistor with resistor
create voltage divider. [11]
We can see most simple way how connect thermistor with microcontroller on
image above. Analog is
connected microcontroller built converter. One side connected the ground and the other ADC
reference, our case 3,3 With the lowest temperatures the impedance thermistor
will near infinite and ADC will measure near the other hand the higher
temperature put impedance near values and will measure 3,3 with ADC. Its resistance
in 25°C ambient and measurement range -40 125 °C. Hence the measurements temperature between stated values can be
enumerated with linear approximation equation calculation stated above. Thermistor has
± diversity impedance value, degree calibration will necessary. Data-sheet of
this component has complete table impedance for each change within the whole
range.where [-] temperature coefficient and [K] change temperature. It’s from Arduino temperature measurement test application.
There are two types thermistors [10]:
● PTC Positive temperature coefficient. Temperature coefficient negative. The resistance decrease with increasing
temperature.11: Thermistor connection [12]
12
