Weather station tracks and stores all measured values for maximum and minimum value. (unexpected input voltage ADC0 to ADC2), the symbol "_" (value less than the allowable range) or " ‾ " (a value higher than the allowable range) is displayed.ĭata is refreshed about every 3 - 4 seconds.
If the value is out of range or sensor has malfunctioned The first part of the display shows the temperature, the second one relative humidity and third shows the atmospheric pressure. Weather station is powered from a stabilized 5V power supply with the 7805 regulator in typical application. Is not critical for analog-to-digital converter (ADC). When measuring each variable, more samples are always taken and averaged to eliminate random errors (noise).ĪVR IO4 is using built-in RC oscillator running at 1MHz as a source clock. R1 to R8 determine the current of display and thus the brightness.įor measurement of analog signals three unbalanced inputs of 10-bit AD converter circuit ATmega8 (A) (L) are used. Frequency of multiplexing is about 100Hz. Cathodes are connected to port D,Īnodes to entire port B and PC5 pin through current amplifying transistors T1. The displays are controlled by multiplexing as a single 9-digit display. The barometer uses a four-digit display, hygrometer two- and thermometer three-digit display. To view the values LED display is used. The barometer measures air pressure in hectopascals range 150.
Humidity meter (hygrometer) measures the relative humidity in the range of 1. The thermometer measures the room temperature in the range 2.0. You can also use MPXHZ6115A, MPXA6115A, MPXAZ6115A or MPX4115A. Pressure is measured by circuit IO1 - integrated pressure sensor MPXH6115A. The output voltage linearly dependent on the temperature with coefficient of 10mV / ☌.Īs the humidity sensor IO2 I used integrated sensor HIH-5030 (you can also use improved HIH-5031). Temperature is measured by the integrated circuit IO3 LM35. The circuit is controlled by a microprocessor IO4 - Atmel AVR ATmega8, ATmega8A or ATmega8L. It allows you to set the orientation weather forecast.įor all three measured values minimum and maximum are stored and that can displayed or reset by buttons. This simple homemade weather station can measure and display all the basic meteorological variables -Īir temperature (thermometer), relative humidity (hygrometer) and atmospheric pressure (barometer). Simple weather station (thermometer + hygrometer + barometer) with AVR
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