i am doing lux meter using Photo-transistor(TEPT4400) with microchip controller. I got resistance value from ADC samples but I dont know how to convert resistance to lux. Please help me to find out.
This is my circuit
3.6 V ------/////----|----___/-----| |GND
10K /^/^ |
photo transistor (TEPT4400 )
Hole controller will be working on 3.6v Battery supply.
This is my adc(10bit) Code
average = 0;
for(val=0; val<NUMSAMPLES; val++)
average += samples[val];
average /= NUMSAMPLES;
average = 1023 / average - 1;
average = SERIESRESISTOR / average; // Photo resistance value
is my formula in the code is correct?
what i have to do further to get lux value?
Anybody give me the formula