TTN Uno doesn't power up when not using the MicroUSB port

(Marin10019) #1


My TTN Uno powers up fine if using the microUSB port but if I try to connect a battery to it using the other port (which I don’t know the name of, sorry) it never works, altought it works fine if I use the same battery on an Arduino UNO using the same port. Anyone has the same problem? Is it even supposed to work in the first place? I tried on another TTN Uno board and it still didn’t work, I don’t know why.


do you mean you connected a battery (what type of battery ?) to the power jack ?

(Marin10019) #3

Yes, the power jack, and it was a regular 9V battery


9v should work.
is your code expecting a serial connection ?

(Marin10019) #5

No it doesn’t expect one, we already managed to power the board up by using a phone battery using the microUSB port without any other connection but we’d like to do it using the power jack

(Gijs Mos) #6

Found the issue. I have 2 boards here. Revision number 094846A0 Jove JVE0S2 etc.

The original TTN-Uno was exactly like the Leonardo. There was a protection diode that simply shorted out the power when you swapped plus and minus.

In the new version a series diode was used from the + (center) connection of the barrel connector to the input pin of the regulator. More friendly than shorting out the power at the cost of a small voltage drop.

However, on both of my boards the diode polarity is still as in the old version. Mening it just blocks all current now.

Only fix seems to be to solder it out and back with the polarity swapped.

I did a lot searching for schematics of the newer board. No luck. There is a schematic going around of an older version where the power is still similar to the Leonardo but that is clearly not matching the newer board.

Can the newer schematic be published so I can repair the board? Or can someone with access to the schematic at least confirm my diagnosis and proposed cure (reversing the diode).

The Things Uno: Is there updated documentation?
(Gijs Mos) #7

Alternatively you can power on the “arduino” connector. The Vin pin is connected to the input side of the regulator, after the diode. So no blocking here.

Thinking about it, when you do this you could use the barrel connector as a power output :wink:

(Marin10019) #8

Hi, thanks for the answer! We thought about trying the connector, we’ll probably go with that yeah, at least until we get the schematics^^