Power connection problem


#1

My weather station project involves an Arduino Pro Mini. In the local station, power would normally be supplied to the Pro Mini from an FTDI USB connection which allows received data to be logged in Excel. In some circumstances it might be used as a stand-alone unit merely displaying received data on an LCD display. As a stand alone, power would be supplied to the Pro Mini from the on-board regulator.
180703-LWS-Circuit.pdf (55.0 KB)

To allow for both configurations I included a two-pin connection
https://www.altronics.com.au/p/p5492-oupiin-2-way-2.54mm-pcb-mount-pin-header/
https://www.altronics.com.au/p/p5472-oupiin-2-way-2.54mm-crimp-housing/
I can use as a bridge. In data-logging mode the there would be no connection from the on-board regulator to the Pro Mini - in stand-alone I would plug in a bridge (and unplug the FDTI breakout :upside_down_face:) to connect the Pro Mini to the regulator. This creates a problem with the Electrical Rules Checker:

How can I deal with this so that everything is kosher?


#2

This is the same error you had here: Musical chairs with Electrical Rules Ceck

Add a power flag for the same reasons in that other thread.

As my choir director says: “Make a new error, I’m tired of that one.”


#3

'Scuze me, but the power flags are on the regulator sub-circuit. Without that 2-Pin_Outlet (O2) the ERC is fine.

You gotta admit, I’m inventive. This is a whole new error :grinning:.


#4

Look at the ERC, type 3. Pin 9 of the Pro Mini (labeled VCC) is a power input. Likely pin 1 of the connector (O2) is a passive pin. So you have a net that has at least 1 power input but no power outputs to drive the net.

So, same error but different clothing.


#5

That is precisely the condition which would exist in reality in data-logging mode where the IS no connection between the regulator and the Pro Mini. So it is not actually an error - merely a factual report of an intentional situation. I guess the action is to ignore the error report and get on with building the PCB.

Sorry to have bothered you all with this. :pensive:


#6

What does that have to do with anything? The connection between the connector and the Arduino is always there. Make the pin of the connector the correct type or add a power flag, exactly the same way you have dealt with this error many times already.

Although I would design it so that no “bridge” was necessary, but just connect or disconnect the FTDI board as needed.


#7

Hi 1.21Gigawatts

I haven’t been able to figure out a way to do that. The problem is that if you have the Pro Mini powered from both the USB and the regulator things get very interesting. The two are mutually exclusive. Having a bridge (or not) was my only solution. I am all ears, so to speak, if you have another.

Thanks