Hi there,
I have a project in mind in which i have 100 LDRs. I want to detect which LDR is active. Much like an LED art but reverse. Can anyone help me regarding which parts I should use to detect exactly which LDR is active?
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LDRs are always active as they are resistive. You need to decide the switch point. Mega boards have 50+ inputs but some are pure digital and would need a matching resistor to hit the switch point while the analog inputs allow software do decide the switch point.
for a start have a look at Using An LDR Sensor With Arduino
for 100 LDRs you would need to use an analogue multiplexor
Do you just want to know which is illuminated, or how strong the illumination is?
If you give more details of your project you will get more helpful advice.
You might be able to wire in a matrix - 10x10 meaning you only need 20 I/0 and scan around them to see the “active” ones - have a look at led cubes and key pads for ideas on how tackle this
I just want to know which LDRs are active and Which parts should I use to create the grid as I have to use 200 I/O
Can you define what an 'active' LDR is?
And is there a possibility that more han one LDR is active?
If the purpose is to 'see' then post#6 beat me to it.
Put the LDR's in a matrix and scan the matrix for their various values.
LDR's suffer terrible hysteresis when using them to try to 'see'. Photodiodes would do a much better job; such as a BPW34.
A infrared camera would even be better, like a AMG8833 or it bigger brother for seeing. I use 2 AMG8833's to detect animals.
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