You have probably noticed that all Yoctopuce USB devices use micro-USB connectors which are the smallest available. But for some applications, a USB micro B plug is still too big. This week we will explain how to wire your Yoctopuce devices without USB plugs.
Actually the plug is as big as the device
All yoctopuce devices have 4 soldering pads, right behind the USB connector. You can use them to solder an USB cable directly on the board. You have to cut a regular USB cable. You will find inside four tiny wires, one red, on green, one white and one black. You just need to solder them on the board, just make sure you respect polarity
|USB Vcc||[ + ]||red||round|
|USB Vss||[ - ]||black||square|
You can solder an USB cable directly on the board, but it's quite tricky
Although it's doable, it is not easy at all. The tiny colored wires are stranded wires, that means you need to carefully tinplate them before trying to stick them into the pads holes. Unfortunately these wires are not meant to be soldered. The insulation starts to melt as soon as you heat the wire a bit too much. Moreover the result is fragile. The wires can be torn off quite easily, and once it is soldered the cable cannot be disconnected.
There is an alternate method based on Board2Board-127 connectors available on Yoctopuce shop.
You need Board2Board-127 connectors
The idea is to solder one the connector to the board, which is much easier than soldering those four tiny wires. The other connector must then be soldered on the USB cable.
One connector on the board
The other one on the USB cable
You will get a fragile assembly on your USB cable but a protection can be made quite easily. You just need a hot glue gun.
Go near a water point and put a small amount of hot glue on the wire. Wet your fingers and start to model the glue while it's still hot. Having wet fingers will prevent the glue from sticking on them and you won't burn yourself. If you work fast enough, you will get a nice little USB plug of the shape you want.
Wires are protected with hot glue.
Et voila! in a matter of minutes you made yourself a quite compact USB connection. Be careful though, this connection is no more foolproof: if you plug it the wrong way, this will cause a disaster..