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[on:]

Hey all

Background, I am building a prototype that has an internal circuit board controlling RGB LEDs.  Due to size restrictions on the actual prototype I have to use the Pro Mini 5V board to install in the casing. Also, I need to power the board with a series of to 3V batteries (for a total of 6V) instead of the 5V supply from the USB.

I did all of the intial circuit building and programming with an UNO board. I tested the UNO circuit with both the USB 5V supply and the exact 6V battery supply that I am using. Everything works perfectly. I soldered up the circuit and components completely on the Pro Mini 5V board. I tested it with the USB 5V supply attached to the computer and it works perfectly.  However, when I attach the 6V battery supply it will not work.  Each time I press the button in the circuit the board seems to reset. 

Any thoughts or help?

My initial assumption is that the Pro Mini 5V can not handle the 6V supply and resets to protect itself. Any help is greatly appreciated.

newt

[Reply #1 on:]

The pro mini uses a voltage regulator with a much lower current output compared to a Uno.  So it is possible the regulator is shutting downing, causes the atmega to reset.

What is connected to the Vcc (or 5v) pins of the pro mini?

[Reply #2 on:]

What pin are you connecting the 6V to?

[Reply #3 on:]

Apparently the voltage regulator is a MIC5205-5.0YM5. It can output 150 mA.

[Reply #4 on:]

Hey

I am attaching the positive from the battery supply to the vcc and the negative obviously to ground.

If I use a resistor between the supply and the vcc pin, will that fix the problem?

Mike

[Reply #5 on:]

If I use a resistor between the supply and the vcc pin, will that fix the problem?

The problem hasn't really been identified, so it is hard to say what will fix it.  You only have symptoms at this point.

Do you have a multimeter?  I would verify the voltage the battery is putting out when attached to the circuit and, if possible, watch it when the button is pressed.

I would also suggest posting a schematic of what the rest of the circuit looks like, to help identify problems.  For example, are your buttons using pull up or pull down resistors?

[Reply #6 on:]

Hey

Ill give it a check with a multimeter and see what the draw is normal and open.

Don't have a legible schematic right now. The button is currently using a pull up resistor. How would this affect the function of the circuit? I'm curious.

I am still leaning towards the voltage as it is the only changing variable. Like I mentioned, it works perfectly with the 5v usb attached to the VCC.

I'm going to try a resistor between the battery supply and the vcc pin. Also trying to track down a 5V or combination battery source.

Thoughts?
Newt

[Reply #7 on:]

I am still leaning towards the voltage as it is the only changing variable. Like I mentioned, it works perfectly with the 5v usb attached to the VCC.

USB is an active supply while batteries are a passive supply.  By that I mean compare the two.  The USB supply is better regulated and may be providing some current limiting.  Batteries will show just show a decreased voltage in the presence of a high current draw.

It could be there is a wiring mistake with the Pro Mini setup that is better protected when used with USB than when used with the battery.  This is why I suggested making voltage measurements to get an idea of what is going on.

Have you taken the batteries back to your Uno to make sure they have enough energy left to work correctly?

[Reply #8 on:]

PHEW!!

Got it working on the Mini! 

I tested all of the things that you had recommended (testing the draw, re-checking with the uno) and again everything seemed fine.  However, your comment about the pull up vs down resistor got me thinking. So I switched the resistor and presto, it works perfectly again.  Not sure why the difference between the UNO and Mini Pro, but hey, it's working now.

Thanks for all your help.
newt

[Reply #9 on:]

What value resistor are you using?

[Reply #10 on:]

For the switch, 10K 1/6W.

[Reply #11 on:]

I am attaching the positive from the battery supply to the vcc and the negative obviously to ground.

Yes, but you aren't supposed to do that:



See: http://www.arduino.cc/en/Main/ArduinoBoardProMini

RAW. For supplying a raw (unregulated) voltage to the board.

You are putting 6V into the VCC of the processor. It isn't designed for that.

The RAW pin is for the unregulated input, and that goes through the voltage regulator.