MKR 1000 & MKR ETH Shield power supply

I'm using a MKR1000, attached I have an NFC module and an Arcade button. When I attach them directly to MKR1000 it works as expected. When I add an Arcade Button to it, it won't work as expected, as there is not enough power (light is low, and get signal from input that the button is always pressed)

Wiring is as follow
MKR 13 RX to Button Light
MKR GND Button Light
MKR 9 SKC Button Click
MKR GND Button Click

So I have multiple things attached to GND, but as said, issue only shows when MKR ETH SHIELD is inbetween. Any ideas?

Is there any mode to add additional power to the Shield or Button? Is the issue the GND chaining of all 3 devices (NFC, BUTTON, BUTTON LIGHT) ?

Thanks for any help

A schematic about now would be exceptionally useful even if it is hand drawn.

Some external components may require thier very own power supply and then a COMMON GROUND.


Thanks for your answer. I just drawn a schematic, I hope it's more or less clean. In Reality MKR1000 is stacked on the ETH shield, and all cables are on the shield pins, if I remove the shield, I have everything working.

Only power source is USB on MKR1000.

One Special thing, GND is wired from MKR1000 -> Light GND -> TO BTN GND -> TO NFC GND.


Couple of things.

Is the NFC a 3.3V or 5V or DUAL mode one ? If it 5 volt you may be exceeding the 3.3 volt pin specification.

Second is what is the light on the arcade button and its current draw as that too might be exceeding the pins limits.

Third item is that it may be some of the pins you want to use are conflicting with the ethernet shield.
Specs here and they show
MISO, MOSI, SCK, RESET, 4, 5 being used. GND does not matter.

The specs are HERE btw.


Bob, thanks for all the hints

  1. NFC: I'm using and its on I2C, so it uses 5volt

  2. The arcade button has a light and it's low. Button is identical to this one, Blue LED Illuminated Arcade Push Button again 5V

  3. Thanks for that info.

So assuming on this I have to
a) Move the SCK to another pin which is not used
b) Get 5.5v power for Light and NFC

Sorry for the stupd question, but in this case you just add a second powersource (and if, what) or is there a easier way to power the arduino and the 2 other parts with same power source?


They are not stupid questions.
We all started somewhere.

There are lots of different ways to both power your add-ons AND the Arduino.
Most common is 5 volts to the VIN pin and ground and simply share those to your other devices before the MKR.

Make sure your external supply is also capable of supplying the correct (or more ) current in terms of A or mA etc.

Please remember that the MKR expects inputs to be 3.3 volts in terms of input limits from sensors so if your NFC supplies 5v TTL you will need a level shifter to lower that to 3.3.

It doesn't sound much from 3.3 to 5 volts but one can destroy the other.
The MKR1000 is only 5 volt tolerant when OUTPUTTING to a 5 volt device not INPUT !