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Circuit Playground Express A0 Clicking and LED Brightness
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Circuit Playground Express A0 Clicking and LED Brightness

by alextangen73 on Wed Apr 29, 2020 1:49 am

Hello,

I hooked up 4 strings of fairy lights to A0, A1, A2 and A3 on a circuit playground express board. Every time the LEDs hooked up to A0 go on and off circuit playground express makes a clicking noise. LEDs on other I/O pins are silent when blinking on and off. Why is A0 clicking. This does not occur when the same code is uploaded to a circuit playground classic.

The LED hooked up to the pins above are very dim. I have the exact same code uploaded to a circuit playground classic board and the strings of LEDs hooked up to the I/O pins are MUCH brighter. Why is circuit playground express outputting less power?

Thank you!

alextangen73
 
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Re: Circuit Playground Express A0 Clicking and LED Brightnes

by dastels on Wed Apr 29, 2020 9:31 am

A0 drives the speaker on the CircuitPlayground Express. So when you change the voltage on it, it gives the speaker a little kick.

From the tutorial guide:
A0 (a.k.a D12) - This is a special pin that can do true analog output so it's great for playing audio clips. In can be digital I/O, or analog I/O, but if you do that it will interfere with the built-in speaker. This is the one pin that cannot be used for capacitive touch.


As to the brightness, they are two very different boards. The SAMD21 can only supply 10mA on each pin, while the 32u4 can supply 20mA. You will probably be better off in either case using a transistor to drive the strings rather than connecting them directly to IO pins because of the current requirements.

Dave

dastels
 
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Please be positive and constructive with your questions and comments.