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Pull up resistor for reset pin ATmega 328P

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I'm a little confused as to what resistor I need to use for the reset pin on my AVR.

The datasheet for my AVR says minimum 30K however the programmer ( Avrisp MK2) says it should be no higher than 4.7K otherwise it detects it as a short which is what happened when I put a 10K resistor in. My supply voltage is 5V.

from the datasheet for my avr chip
0.1Volts is the maxiumum voltage it will register as logical low.
VCC + 0.5V is registered as logical high.

Also may I ask if an ouput pin is turned logical low, does that mean it will sink current?
 

ericgibbs

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I'm a little confused as to what resistor I need to use for the reset pin on my AVR.

The datasheet for my AVR says minimum 30K however the programmer ( Avrisp MK2) says it should be no higher than 4.7K otherwise it detects it as a short which is what happened when I put a 10K resistor in. My supply voltage is 5V.

from the datasheet for my avr chip
0.1Volts is the maxiumum voltage it will register as logical low.
VCC + 0.5V is registered as logical high.

Also may I ask if an ouput pin is turned logical low, does that mean it will sink current?

hi,
Looking at the Avrisp d/s it says 'should not have a stronger pull up than 4.7K, which I would interpret as it should be higher than 4.7k.???

A pin set as a output will sink current when low and source current when high.
 

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Last edited:
Just to check I've wired it up correctly.
I've wired the pull up resistor to the vcc then the other end to the reset pin of the avr. Then off that wire it's connect to the reset pin of the Avrisp mk2 header.
 
Last edited:

ericgibbs

Well-Known Member
Most Helpful Member
Just to check I've wired it up correctly.
I've wired the pull up resistor to the vcc then the other end to the reset pin of the avr. Then off that wire it's connect to the reset pin of the Avrisp mk2 header.

hi,
This the circuit from the web.
 

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