ATMEGA Connections help

Hey fellow developers and hobbyists,
I am working on a project trying to rebuild an arduino board. I made a few connections that I wasnt fully sure of yet and wanted to get feedback from more seasoned designers.

  1. I am trying to wire up the reset button using a push button. The push button has 4 terminals, i wired one side to ground and the other side to the reset line. I left terminal 4 unwired since it did not make sense to me to wire it. Is this correct or should i be using something else? Please see the image with the reset button.

  2. I am integrating an NRF24l01 breakout onto my board, and in the past i have worked with these boards but found that I need to place a capacitor between vcc and ground. In my boards design for the regulator, i already have a 22 uF capacitor on the output which is basically connected to the nrf sensor’s vcc, is this sufficient or do i still need to add the capacitor. I added one in my design just in case but i wasn’t sure if its excessive. Please see the image attached.

Thanks for reading and your input is greatly appreciated.

. I added one in my design just in case but i wasn't sure if its excessive.

I assume you are an electronics newbie, so FYI, it is impossible to have too much capacitance, (at least not without maxing out your credit card)

Standard procedure is to look up the datasheet for the regulator in question and consult the test schematic at the end of the datasheet for circuit components required. This would be done by Googling the Mega schematic to find the regulator part number and then googling the datasheet for that part.

Normally , as a general rule a 1uF on the input and output and 22uF on the output is sufficient.
If you want to follow the datasheet recommendations you can read the following:

MC33269D-5.0

An input bypass capacitor is recommended to improve
transient response or if the regulator is connected to the
supply input filter with long wire lengths. This will reduce
the circuit’s sensitivity to the input line impedance at high
frequencies. A 0.33 F or larger tantalum, mylar, ceramic,
or other capacitor having low internal impedance at high
frequencies should be chosen. The bypass capacitor should
be mounted with shortest possible lead or track length
directly across the regulator’s input terminals. Applications
should be tested over all operating conditions to insure
stability

darkblader429:
The push button has 4 terminals, i wired one side to ground and the other side to the reset line. I left terminal 4 unwired since it did not make sense to me to wire it. Is this correct or should i be using something else?

You need to check with a multimeter, so you are sure …

darkblader429:

  1. I am trying to wire up the reset button using a push button. The push-button has 4 terminals, I wired one side to ground and the other side to the reset line. I left terminal 4 unwired since it did not make sense to me to wire it. Is this correct or should I be using something else? Please see the image with the reset button.

Hi, as already been mentioned you have to check with your multimeter the pinout of your push button to verify which pins are internally connected and how the connection changes after pressing/releasing the push button. If at the pinout of your push button pins 3 and 4 are common (this is the most common case in tactile switches) then I do not see any reason to left pin 4 unconnected (just connected with pin 3).

No need for a multimeter, just wire the push button to any two diagonal connectors and ignore the other two. That is don’t connect anything to the other two.

If you use a solderless bread board that men’s putting the button between the gap in the middle.

Thanks, for the help guys, i will do that.

Breakouts normally have their own decoupling capacitors on-board. If in doubt add 0.1µF as close as possible to
the pins between Vcc and ground. Extra decoupling never hurts.

Hi,

darkblader429:
I am working on a project trying to rebuild an arduino board.

Are you rebuilding or making a new PCB?
What model Arduino are you basing it on?
Can you post a copy of your schematic AND PCB patterns?
Thanks.. Tom.. :slight_smile: