LIME2 mini USB power mod

[Jookia]

Greetings! I've always wanted to be able to power my Lime2 from USB, but it's never worked properly. I read somewhere that this is due to the PMIC limiting current from USB, which makes sense.

I soldered a 1N5819 diode on the corner of the board under the power plug, with the anode on the side of R67 next to the text, and the cathode near D4's pad on the side near the D4 text. This connects the mini USB VBUS to the 5V EXT rail.

This has managed to let me power the board over mini USB, with the 5V rail running around 4.5V (it usually runs around 4.7V). The diode prevents damage if the board is powered from the 5V rail already.

I've tested this and it seems to work. So I'm just throwing this up here for anyone interested.

Edit: I do want to make clear that this power method is limited to 1A due to the diode. Using a MOSFET as polarity protection or just running a wire and not plugging in both power sources at once would work better, but keep in mind mini USB cables are not generally rated for high power use or charging things.

[Jookia]

I've been running this for a few days now doing compiling and GPIO stuff as well as driving Ethernet, it's been going pretty good. Today I sat down and set up USB gadget so I can run Ethernet and serial over the USB cable. Being able to just plug in my Lime and SSH to it troubleshoot it over serial is fantastic, and a great experience for any type of embedded development. You can enable this by doing 'modprobe g_multi'.

The downside is having to set up your host machine to route traffic through the Ethernet interface, and set up the Lime to get Internet over the interface. It's very much worth the time and energy if you can handle it!