Multiplexing analog inputs
i'm planning target board throwing ball against wall. first approach use piezo elements detect hits. second approach using velostat sheets detect pressure ball. second approach got me idea, nothing new, anyhow, couldn't quite find similar on forum.
a stripe of velostat can detect pressure. used resistor, can act voltage divider:
pressing velostat stripe cause voltage @ a0 drop. thought of replacing resistor stripe of velostat:
pressing other stripe cause voltage @ a0 rise. sure 1 can add more strips same analog input a0, since we're talking velostat sensors, there problems accuracy. far have 2 stripes per analog input, should ok. @ startup, value @ a0 read , saved. then, when in action, 1 have care of voltage raise or voltage drop. it's accurate digital input.
pressing on both stripes @ same time cause resistant drop in each stripe, cause voltage @ a0 to... well... unstable , unreliable. , in worst case total resistance drop , cause near shortcut between 5v , ground. if there's risk this, additional resistor should placed there. each stripe ring. 6 analog inputs, 1 have 12 rings.
so next thing arrange stripes in target board pattern. since 2 rings share same analog input, each pair should far each other possible, ball hit never trigger both rings in pair. this:
here have 6 pieces of velostat, need 3 analog inputs.
a stripe of velostat can detect pressure. used resistor, can act voltage divider:
pressing velostat stripe cause voltage @ a0 drop. thought of replacing resistor stripe of velostat:
pressing other stripe cause voltage @ a0 rise. sure 1 can add more strips same analog input a0, since we're talking velostat sensors, there problems accuracy. far have 2 stripes per analog input, should ok. @ startup, value @ a0 read , saved. then, when in action, 1 have care of voltage raise or voltage drop. it's accurate digital input.
pressing on both stripes @ same time cause resistant drop in each stripe, cause voltage @ a0 to... well... unstable , unreliable. , in worst case total resistance drop , cause near shortcut between 5v , ground. if there's risk this, additional resistor should placed there. each stripe ring. 6 analog inputs, 1 have 12 rings.
so next thing arrange stripes in target board pattern. since 2 rings share same analog input, each pair should far each other possible, ball hit never trigger both rings in pair. this:
here have 6 pieces of velostat, need 3 analog inputs.
no direct experience velostat sounds should work, @ least can't see wrong.
you'll have testing though find out how changes resistance, , whether may need amplify signal.
a potential problem see detection: have , poll analog ports impact of ball lasts short time (i expect few milliseconds @ most). arduino's adcs may slow that, have poll them 1 one.
you'll have testing though find out how changes resistance, , whether may need amplify signal.
a potential problem see detection: have , poll analog ports impact of ball lasts short time (i expect few milliseconds @ most). arduino's adcs may slow that, have poll them 1 one.
Arduino Forum > Using Arduino > Sensors > Multiplexing analog inputs
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