My Propeller keeps resetting - why?


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5 months ago by
I have built my first Propeller circuit and copied the example on page 17 of the Manual exactly.

I can download my program into the EEPROM with my PropPlug and it runs fine, but when I remove the PropPlug the circuit becomes unstable.  It seems to be resetting itself all the time.

What have I done wrong?




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1 Answer


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5 months ago by
This is a common problem for those new to the Propeller.
There is an unfortunate omission in the Manual's example circuit diagram.

Try adding a 10,000 Ohm resistor between pin 12 (VDD) and pin 11 (RST).

This is commonly known as a "pull-up" resistor.  In a nutshell, without the PropPlug attached, the RST pin is in a "floating" state, meaning that is subject to electromagnetic interference which can easily cause your Propeller to reset itself.

The pull-up resistor prevents this floating state (by literally pulling the voltage on RST up to near 3.3 Volts) which prevents resetting.

https://en.wikipedia.org/wiki/Pull-up_resistor
1
According to the same manual with BOE tied low RST already has an internal 5k (pull-up) resistor. Are you saying that's not enough?
 
written 5 months ago by kuroneko  
In my experience RESn can still be sensitive and glitchy.  I tend to use 4k7 or 10k resistors and have not had further problems.
written 5 months ago by Woss Code  
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