I’m working on the set-up of the pixl board with an Ergo Jr and a Raspberry Pi 2. So far everything works well but it becomes a little bit more strange when I tried to plug LiPo battery on it.
For what I know lipo batterry most common connection are with + to the right of the keyed connector and - to the left. It’s the same on standard LiPo charger like Adafruit one and many others. Anyhow and according to the schematics it’s the opposite on the Pixl Board… is it a real choice or a kind of mistage ???
The other question concern the charging of those LiPo, it doesn’t seem possible to charge them via the DC power supply and I wonder if an onboard charging circuit has been considered at one point ?
Sylvain, can you please provide some details about the LiPo battery you use? I believe you are using a 1S LiPo (1 cell = 3.7V) which will not work with Pixl. You will need a 2S battery (7.4V).
And no, for the time being the Pixl only converts the 7.4V from the battery to 5V for Raspberry Pi and passes 7.4V to the Dynamixel bus. No support for charging for the time being - and I doubt there will ever be because it would complicate the design significantly (charging a 2S is totally different than a 1S LiPo).
I use two 3.7v battery. Power supplying and battery system are not what I know best but I was thinking that basically a 2-cell battery is just 2 x 1-cell in serie and so far that the two header on the pixl board was intend to plug those two batteries.
First of all I apologize in advance for my bad English.
That’s normal, the two battery connector was designed to be used with the Robotis battery (http://www.robotis.us/li-ion-battery-charger-set-lbb-040/).
And these batteries don’t have the same polarity as standard Lipo battery as you can see in this picture:
It was a choice for the Poppy team to have a compatibility with the Robotis robot, but we definitely have to communicate about this issue to prevent problems.
For your problem I have two solutions: you can try to unsolder the two connectors and resold them in the right way. Actually, this is the pixel board pinout for the connector :
Hello and thanks a lot for this precise answer. The unsolder solution is what I’ve tried before repporting on the forum. Unfortunately the connector cases is not symetrical and it was not possible to resolder them properly the other way.
I’ll give a try to the optionnal connector or take time to design a new board with integrated charging system. It seems in my capacities and funny to do it juste time eating so I’ll see if I find time.
Ok, good initiative, keep us in touch about your board design if you want some feedback.
The actual project (schematic, routing and bill of material can be found on CircuitMaker).
If you ever have a problem about this way I can send you a zip folder containing everything you need).
