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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.
sampled 128 values,
program stay loop for 128 cycles. Values below correspond
with 170 m/s. 12500 clock cycles, timer has lower value than 15000, digital
input interrupt could happened because received noise some reflected signal. flag fulfill
this condition, program exit from function. Program returns measured time and exit.
The function has adc_array address input argument. There are some correction
of this error later.
At the end test value correct range. In
that case set flag for next measurement.11: Flowchart GPIO post interrupt function
4.4. we
multiply this number 3,3 and divided 1000, had peak peak voltage of
received signal. every step takes one value from adc_array and
store adc_value local variable. Digital input interrupt pin level disabled and flag set next
state, X_WIND_CALC Y_WIND_CALC. This can happen for too low measured time.
At first program clear max and put min high value.9 ADC peak peak function
The adc_peaktopeak function called after gpio_post_int from main function. Actually this value
can from 2500 5000 higher because another details. first is
defined variable. Than actual adc_value tested higher than max
28
. Then tested flag set X_PWM Y_PWM state.
Illustration 4. were discounting from 31250 (2,5 ms) and signal
takes 1,5 spread between sensor, has measure 18750.4.
After that get value from timer and calculate measured time as
a complement timer_load_set. There are local variable on
the beginning.8 GPIO post interrupt function
The gpio_post_int function called from main after adc_sample function.4. Then tested flag parameter let know, which PWM generator
has switch off. It
calculate difference between maximum and minimum sampled sequence
