[Resolved] Arduino Mini(5v) 4.96v cannot upload program


I have an arduino mini(5v) that is connected to a seeedstudio solar shield and a 3 watt solar panel. I have the 5v and gnd of the solar shield hooked to the 5v and GND of the arduino. The actual reading when hooked up is about 4.96v. I've read on a few forums that this should be fine, but when I try and upload a program using only tx and rx lines from a usb-ttl adapter, there is no communication. If however, I hook up the power lines from the usb-ttl adapter (5.15v) everything works as expected.

Just to make sure I wasn't going crazy, I used two separate power wires to power the arduino (5.05v) and only the tx/rx lines of the usb-ttl to transfer the program and it worked. So it seems that 4.96v is not enough for tx/rx communication with a usb-ttl adapter. This gives me much concern for my project which will use the tx/rx lines to a xbee module. I haven't received the xbee module yet so I haven't tried it.

What are your thoughts? Am I okay with 4.96v and I just have to power it differently when uploading a program? Or is this solar setup bunk and I should get a refund?

Also, should I be hooking the 4.96v lines up to the 9v port instead of the 5v port of the arduino mini. It doesn't seem like the seeedstudio solar shield is exaclty stable 5v. I just wasn't sure if the 9v had a minium rating.


I'm new so be nice :slight_smile:

" using only tx and rx lines from a usb-ttl adapter, "

You need RX, TX and Ground.

And if you don't use DTR/RTS for auto-reset you will also need to do a manual reset.

Thank you very much! That did it. Heh, silly. Really happy right now. I guess when I powered it from another usb port, it must have connected using the shared ground in my computer.