I've just found, somewhat accidentally (EDIT: well, maybe not accidentally - more out of curiosity), that the DC-IN connector happens to be the same size as a standard 2-pin fan connector. When plugged in, the fan spins very well and in the correct direction. This will greatly simplify adding a fan for me rather than adding a J4 connector and modifying the wiring for the fan. Is there any potential issue with this? I don't see how but figured it was worth asking. The fan is a 12v 0.05A 40mm. This is mostly an informational post but if anyone sees good reason to avoid using the DC-IN to power the fan please let me know
Looks like some bad labeling - typically, when they say "-IN" its an "input" - so if that were right, this should've been the equivalent of a 12V DC-input in place of the external/barrel jack connection. If it is providing 12V out (from the 12V barrel jack input VIN), then it should've been marked DC-OUT, no ;?) Unfortunately, especially in the case of some jumpers, the use of non-std sizes and the lack of proper documentation, is causing unnecessary experimentation and waste of time :-( All "I/O" should be well documented, for obvious reasons. We cannot peek into the designers brains to figure intent /v
well actually the DC-IN is a correct label. That port is not intended as a DC-output, however, as you noticed it will serve that purpose if the UDOO is powered from the DC Barrel jack. That port is intended to hook up an external battery or power supply using a JST connector. the circuitry of the board shares the + and - lines with the barrel jack so what happens is when you apply power via the barrel jack its measurable from the DC-IN and vise-versa. so when you power the barrel jack the DC-IN pins have power which can be used as an output, but that is a byproduct of the design, not its intended use/design
Thanks for the clarification. I was confused between this and the "Ext. Bat. J1" (also a different JST type) connector... If J1 is meant for an RTC coin-cell, may be it should be labelled such and not "Ext. Bat." - just a thought... thanks, /v
yes that is correct the ex-bat is meant to power the RTC the DC-IN is meant as an alternative DC-IN, this could be from a batter, bench supply, or any desired wall source with a JST vs barrel connection. So the labels could be changed, but as you see changing it to batt-in or something might imply its only for a battery, or even imply that it may charge the battery too, which its not designed to do.. so for right now DC-IN still make sense.
Thanks for the clarification DracoLlosa! It was a nice surprise - since I have no intention of running my UDOO off of a battery this works out very well and makes adding a fan quick and easy. Seems it'd be possible to add a second fan through the "normal" fan connector that comes on the UDOO as well if it were needed
