Floating pins
- Thread starter Gramps
- Start date
Never leave an input pin floating
A floating input typically picks up 50/60 Hz hum unreliably
Either set unused pins to output, or provide pull-up or pull down resistors.
Having said all that - receiving unknown signals on an input might not cause a problem in real life - but why take the risk? (confession - I leave spare/forgotten inputs floating most of the time and seem to get away with it)
Leaving the MCLR pin floating would be a really bad idea - and will cause problems for most PIC or PICAXE chips. Provide 10K Ohm pullup for MCLR pin to avoid problems
I ALWAYS provide 10K Ohms resistor MCLR to Vcc whatever the circumstances (or I may risk 100K Ohms if low current consumption is important)
A floating input typically picks up 50/60 Hz hum unreliably
Either set unused pins to output, or provide pull-up or pull down resistors.
Having said all that - receiving unknown signals on an input might not cause a problem in real life - but why take the risk? (confession - I leave spare/forgotten inputs floating most of the time and seem to get away with it)
Leaving the MCLR pin floating would be a really bad idea - and will cause problems for most PIC or PICAXE chips. Provide 10K Ohm pullup for MCLR pin to avoid problems
I ALWAYS provide 10K Ohms resistor MCLR to Vcc whatever the circumstances (or I may risk 100K Ohms if low current consumption is important)
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Yes, that would be the ideal thing to do.
Check out the circuit diagrams for PICAXE development boards such as AXE022P. You will see that a 4K7 resistor is connected pin 1 to V+
10K or 4K7 will work equally well, but maybe you would prefer 4K7 - just to match what is done on development boards
Check out the circuit diagrams for PICAXE development boards such as AXE022P. You will see that a 4K7 resistor is connected pin 1 to V+
10K or 4K7 will work equally well, but maybe you would prefer 4K7 - just to match what is done on development boards
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inglewoodpete
Senior Member
If you're using a 28X2 or 40X2 PICAXE, it is important to wire it up as specified in Manual 1 "Getting Started" at around page 34. It specifies a 4.7k ohm pull-up on the reset pin.
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Gramps
Senior Member
Buzby
Senior Member
My learning lesson ....
picaxeforum.co.uk
20x2
Hi All Just a quick one I have a 20x2 on a board I have made for it for a project I am playing with I make up my own breadboard adapters for the down load side of things when the adaptor is attached the board runs as expected, but when disconnected from the 3 header pins the board does not run...