using the 3.3V supply for other devices

Question about power
Post Reply
YahooArchive
Posts: 1463
Joined: Fri Oct 19, 2012 5:11 am

using the 3.3V supply for other devices

Post by YahooArchive » Mon Feb 04, 2013 8:18 pm

Thank you for you reply Bruce,I'm powering the board using a lipo battery, I
have another board (atmega368 @ 3.3v) attached to 3.3V on the ARMmite, I'm
trying to read the analog output from a Force sensor, powerd @5V, I'm using a
voltage divider to get it to 3.3V. do I need to use another power circuit to
power the other MCU ? thank you



YahooArchive
Posts: 1463
Joined: Fri Oct 19, 2012 5:11 am

Re: using the 3.3V supply for other devices

Post by YahooArchive » Mon Feb 04, 2013 8:20 pm

> Thank you for you reply Bruce,I'm powering the board using a lipo battery, I
have another board (atmega368 @ 3.3v) attached to 3.3V on the ARMmite, I'm
trying to read the analog output from a Force sensor, powerd @5V, I'm using a
voltage divider to get it to 3.3V. do I need to use another power circuit to
power the other MCU ? thank you

There's not much head room on the 3.3V supply of the ARMmite PRO, so you might
be drawing too much from it. The SuperPRO / PRO+ has a larger regulator. You
would need a scope to look at the supply to see if it is cutting out or
excessively noisy.

How clean is the 5V supply to the force sensor? What else is on that 5V supply?
Again using a scope to look at the supply.

basicchip
Posts: 813
Joined: Fri Oct 19, 2012 2:39 am
Location: Lake Tahoe, CA
Contact:

Re: using the 3.3V supply for other devices

Post by basicchip » Tue Oct 01, 2013 10:35 pm

>from the help line
>I/m running a SuiperPro Plus, and would like to tap the 3.3volt regulator to use as a reference on an analog board. I won\'t be drawing any power. Where can I most easily tap into the board?

>thanks

On the SuperPRO, the 3.3V supply is routed to pin 2 of J1, which is the power connection as used by Arduino. J1 is the connector on the bottom of the PCB when all the silk screen is oriented for reading. It is also labeled for Vin, GND and 5V, just no room on the board to have 3.3V on the label.

You can actually pull 100 mA, though sounds like you don't need to.

For analog, you will want to make sure it is quiet, and a ferrite bead is required, otherwise you will probably couple high frequency noise into the A/D converter and it will mis-read.

Post Reply