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Connect 5V power supply

Added by o_cee about 6 years ago

Stupid question of the day, but I couldn’t find clear information about it anywhere. On the JeeNode, where do you connect an external 5V PSU? On the FTDI pins or the battery connection? Does the latter go through the voltage regulator as well?


Replies (3)

Connect 5V power supply - Added by martynj about 6 years ago

o_cee - all of those !  The bat + and the PWR pins at any header go to the input of the regulator chip that creates the 3.3v for the logic.  The FTDI connector p3 can also be used (check that the optional diode position is bridged on the bottom).   The pinouts are documented on the JeeNode Wiki but you are right - it doesn’t explain this well.   There are references to the PWR v. 3V philosophy in some of the Weblog URL’s at the bottom of that page.

You can read documentation just so many times but not spot the flaws - thanks for the question.

RE: Connect 5V power supply - Added by o_cee about 6 years ago

Thanks :)
I think that the guys at OpenEnergyMonitor made their hardware bypass the regulator for the 3,3V battery input, that’s why I wanted to get it clarified for the JeeNode.

RE: Connect 5V power supply - Added by martynj about 6 years ago

o_cee - ‘bypass’ needs some care.  If the bypass is by feeding 3.3V to effectively the output pin of the LDO regulator, beware it will draw some power from that pin. Ok, lets short it out, input to output: also a bad idea, it will still consume some current.  
The only reliable bypass is to remove it, then bridge the input/output pads.  You can get the same effect by disconnecting just the third pin, the ground reference - but while the soldering iron is out, removing completely takes the same time and gives you a part to re-cycle.

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