LowPowerLab Forum

Hardware support => General topics => Topic started by: lilpint97 on February 02, 2014, 03:26:04 PM

Title: Vin pin versus FTDI VIN
Post by: lilpint97 on February 02, 2014, 03:26:04 PM
Does the moteino have a built in voltage mosfet? Meaning, if I apply 12v to the FTDI pins, and have say a 9v attached to the Vin which one will win, and/or has precedence?

Thanks.
Title: Re: Vin pin versus FTDI VIN
Post by: Felix on February 02, 2014, 03:39:30 PM
12V wins, I would say that's a NO NO for Moteino, like to stay at 9V or less.
Title: Re: Vin pin versus FTDI VIN
Post by: lilpint97 on February 02, 2014, 04:47:29 PM
Well might have to put a voltage divider in, I want to use my 12v marine battery.  :P
Title: Re: Vin pin versus FTDI VIN
Post by: lilpint97 on February 02, 2014, 04:50:51 PM
OK, is the winner a voltage winner, or a source winner. Meaning I have a 12/24v to 5v converter from another project I just noticed, but I was going to use a 9v for Vin as a backup like having to move it, or replace batteries, etc?

Thanks.
Title: Re: Vin pin versus FTDI VIN
Post by: Felix on February 02, 2014, 08:55:13 PM
Voltage divider = NO NO. You'd waste a ton of energy that way.
Just use a buck regulator: http://www.ebay.com/itm/4-38V-to-1-25-36V-DC-Buck-Step-Down-Converter-DC-5A-Car-Voltage-Regulator-HM-/400625828810?pt=LH_DefaultDomain_0&hash=item5d472903ca
Title: Re: Vin pin versus FTDI VIN
Post by: lilpint97 on February 03, 2014, 08:23:05 AM
That makes perfect sense, and not try to be dense so which Voltage in on FTDI versus the side headers, which one would be primary in the moteino?

Thanks.
Title: Re: Vin pin versus FTDI VIN
Post by: Felix on February 03, 2014, 08:27:10 AM
If you look at the schematic you will see the VIN on the FTDI == VIN on the side headers (labeled "PWR"): https://github.com/LowPowerLab/Moteino/raw/master/R4/MoteinoR4_schematic.pdf
Title: Re: Vin pin versus FTDI VIN
Post by: Felix on February 03, 2014, 11:30:49 AM
So the VIN on the silkscreen = PWR in the schematic. I should update the schematic to avoid confusion.
That means they are physically interconnected. So when you power the Moteino from FTDI the VIN gets 5V which will then be present on the VIN of the side header (same wire).
When you're done programming and perhaps want to power the Moteino from a battery you can do that through either of the 2 VIN pin holes, on the FTDI header or on the side header.