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Topic: Momentary reset switch Cap question (Read 1 time) previous topic - next topic


Oct 08, 2012, 05:40 pm Last Edit: Oct 08, 2012, 06:28 pm by pcfr33k Reason: 1


I was told to add a cap in series to the Momentary Switch.  Exactly where does it go.  Anyone have a diagram?

If in series does that mean it runs along the reset line and the 1 side of the momentary switch or does one lead of the cap seat on the rest line while the other goes to ground or the ground side of the momentary switch?

Also where along the breadboard does it go.  Before the switch?  After the Switch?  In between the switch and reset pin?
ANyone have a clear diagram?

What exactly is the purpose of the Cap?

Here is a diagram I found.


3rd picture to the right is how I have it setup now.  I measure 100.9 nF for the cap.  That is what the kit came with.

Cap is in-between switch and pin #1 of chip
Next is switch, then Resistor behind the switch ground side and then the other side of resistor is connected to Breadboard Vcc +5.

I measure around +5 when the switch is open and when closed I measure 0 to .00005 volts.

When I burn a bootloader I have to hold down the switch the entire time and not just a portion of the time like when I program the chip.

Any reason that I have to hold the switch down the entire time it programs a bootloader to it?



Take another look at the diagram.  You should notice that the capacitor is not in series with the switch.  Instead, it's in series with the DTR line that would be connected to a serial port for auto-resetting before uploading.  According to the diagram, the only thing in series with the manual reset switch is a 220 ohm resistor, which should be more like 10k according to the datasheet.  220 ohms should work, but seems quite small to me.

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