...but not PWM. I have an l3914a-1 bar graph driver. When I hook up a potentiometer to the signal pin I can make my bar graph react. When I try and do PWM from my arduino pin it fades all ten leds. I've read the datasheet, and checked wiring and resistor values twice. When I measure voltage at the input pin I can see the rise and fall.
The datasheet says 5 volt input. What am I missing?
PWM is not a real variable voltage, it's a PulseWidthModulated squarewave that is basically switching between 0V and 5V very fast.
The analogWrite() value determines the width( duty cycle) of the squarewave, i.e changin the period it is 0v or 5V.
Your led driver probably can't be driven by a PWM signal, but requires a real changing voltage.
You can simulate a real changing voltage by sending the PWM signal through a capacitor, but it does not always work.
Yes of course. Richard is right. The capacitor alone won't do it.