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| en:examples:sensor:photoresistor [2015/11/10 08:51] – heikopikner | en:examples:sensor:photoresistor [2020/07/20 09:00] (current) – external edit 127.0.0.1 | ||
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| ====== Photoresistor ====== | ====== Photoresistor ====== | ||
| - | //Necessary knowledge: | + | //Necessary knowledge: |
| + | [HW] [[en: | ||
| + | [ELC] [[en: | ||
| + | [AVR] [[en: | ||
| + | [LIB] [[en: | ||
| + | [LIB] [[en:software:homelab:library: | ||
| ===== Theory ===== | ===== Theory ===== | ||
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| A range of working temperature is set for photoresistor. Wishing the sensor to work at different temperatures, | A range of working temperature is set for photoresistor. Wishing the sensor to work at different temperatures, | ||
| - | For characterizing light intensiveness physical concept called light intensity (E) is used, this shows the quantity of light reaching any given surface. Measuring unit is lux (lx), where 1 lux represents, the even flow of light 1 lumen, falling on a surface of 1m2. Hardly ever in reality falls light (living area) on a surface evenly and therefore light intensity is reached generally as a average number. Below are few examples of light intensity for comparison: | + | For characterizing light intensiveness physical concept called light intensity (E) is used, this shows the quantity of light reaching any given surface. Measuring unit is lux (lx), where 1 lux represents, the even flow of light 1 lumen, falling on a surface of 1 m< |
| Line 81: | Line 86: | ||
| <code c> | <code c> | ||
| + | // HomeLab photoresistor demonstration | ||
| + | // LCD screen displays the approximate illuminance in lux | ||
| #include < | #include < | ||
| #include < | #include < | ||
| Line 96: | Line 103: | ||
| // Initializing the LCD | // Initializing the LCD | ||
| lcd_gfx_init(); | lcd_gfx_init(); | ||
| + | |||
| + | // Setting LCD backlight to work | ||
| + | lcd_gfx_backlight(true); | ||
| // Clearing the LCD. | // Clearing the LCD. | ||
| lcd_gfx_clear(); | lcd_gfx_clear(); | ||
| - | //Cursor on the position | + | //Cursor on the position |
| - | lcd_gfx_goto_char_xy(3, | + | lcd_gfx_goto_char_xy(3, |
| // Name of the program | // Name of the program | ||
| Line 110: | Line 120: | ||
| // Endless loop. | // Endless loop. | ||
| - | while (true) | + | while (1) |
| { | { | ||
| // Reading the average value of the photoresistor | // Reading the average value of the photoresistor | ||
| - | adc_value = adc_get_average_value(1, | + | adc_value = adc_get_average_value(13, |
| + | // HomeLab II | ||
| + | //adc_value = adc_get_average_value(1, | ||
| // Calculating the voltage in the input of the ADC | // Calculating the voltage in the input of the ADC | ||
| - | voltage = 5.0 * ((double)adc_value / 1024.0); | + | // HomeLab II |
| + | //voltage = 5.0 * ((double)adc_value / 1024.0); | ||
| + | // HomeLab III | ||
| + | voltage = 2.0625 * ((double)adc_value / 2048.0); | ||
| // Calculating the resistance of the photoresistor | // Calculating the resistance of the photoresistor | ||
| - | + | | |
| - | // in the voltage divider | + | // HomeLab II |
| - | resistance = (10.0 * 5.0) / voltage - 10.0; | + | //resistance = (10.0 * 5.0) / voltage - 10.0; |
| - | + | // HomeLab III | |
| - | // Calculating the intensity of light in lux | + | resistance = (33.0) / voltage - 10.0; |
| + | |||
| + | // Calculating the intensity of light in lux | ||
| illuminance = 255.84 * pow(resistance, | illuminance = 255.84 * pow(resistance, | ||
| + | // Dividing variable into two integer variable | ||
| + | // to display it on the screen | ||
| + | int8_t illu = illuminance; | ||
| + | int16_t illudp = trunc((illuminance - illu) * 1000); | ||
| - | // Converting the intensity of light to text | + | // Converting the intensity of light to text |
| - | sprintf(text, | + | sprintf(text, |
| // Displaying it on the LCD | // Displaying it on the LCD | ||
