But to bee clear you don’t need a resistor on the button. The pull up resistor is there to set the input pin in a known state so it’s not ‘floating’, but it’s not a current limiting resistor for say a LED.
@ Gus: But the pin in question would be an input if there is a push button… And the micro powers up tristate with pullup enabled.
If someone connects a button through (pin X) to ground And then configures as an output, then send the pin high, then presses the button!! resistor or no resistor that pin is gone. They must put it down to stupidity…
@ RobV: If the pin is configured as an input it wont short if you ground the pin and it wont fry it you connect it to 3.3v… When you design your project, you know what pins are gonna be input and ouputs. So it shouldn’t be a problem…
Actually this is the first processor I’ve worked on that has pull ups/ downs on Input as well as output.
This is coming from one that has fried a Domino.
I’m wondering. Is it possible to make a safety shield where all pins and the processor is protected, but still would work as normal?
When we play around with these devices on a breadboard errors are easily made. So is it possible to make some sort of safety net for us?
And no, -i’m not thinking of a component shield but something for us that likes to mess around with bare components.
Any time you leave something up to a user to connect, you have the chance of it being screwed up. I don’t think any shield would help here - you connect something that was meant to be to ground to 5v and you hurt things.
@ Geir: Yours was a forgivable error the pins were configured as ouputs and the LE’D’s were current limited.( I gave that some thought by the way, If you had only one resistor and one led was on and the other two were off “I think thats the configuration of tri LED’s” you could short the domino pins quite easily)
Most people incorporate optocouplers in final designs. Bullet proof input / output protection for general purpose pins, We do. they are pence / cents for a quad coupler.
The RGB LEDs where some cheap eBay ones so I really haven’t got any datasheet, but I have used them in the past with no problem.
I do agree that a current limiting resistor on each color is probably the correct way to go, and as the Red color is so dominant it is a good way to balance out the intensity.
However for my Crystal ball I have things behind transistors so I should be ok, but thanks for your interest in my case.
This is how it’s hooked up now.