Miles mentioned there'd be another version of the Xino Basic for Atmel AVR (Arduino) board fairly soon - two months ago, he estimated two to four months, so any day now :

openmicros.org/index.php/component/kunena/2-microcontrollers/1477-xino-basic-arduino-power-connection-a-regulators?Itemid=0

A couple of the reviewers mentioned problems using the ICSP connections on the current v1.5 board, and anyone who's wanted to use them will have noticed the same problems. Firstly, you have to choose whether you want to use the 5 pin Xino connector, or the 6 pin ICSP because they overlap... I want to use both, so a workaround is needed at the moment. Secondly, the ICSP pins aren't in the right order!

I hope the next version addresses these problems. That's the biggest shortcoming with v1.5. The ICSP header has to be in the same place it is now, for compatibility with other boards, but the 5 pin Xino connector could be moved over a little.

Another change I'd like to see is a jumper or two to disconnect the output side of the power regulators from the power rails. That would let me fit the regulator chips but disconnect them completely when I want to use battery power, rather than applying battery power to the output terminals of the regulators, which is maybe not such a good idea.

Does anyone else have changes they'd like to see in the next version?

I'd quite like it if the holes for the shield connectors were slightly smaller, for a better fit. That would mean any mistake in aligning the headers would be less of a problem. I can see it could limit the choice of headers, but that shouldn't be a problem since Ciseco supply those with the board.

I have both ICSP-header and 5-pin header (even extended to 6-pins for RTS) in place. To do this, I moved the 5-pinheader to the bottom. Here a picture:


I moved the plastic on the ICSP-header a bit down before soldering to avoid the pins from coming through the holes at the bottom. They are flat now to keep place for the 5-pins header. As the holes are plated, it's still OK to solder.
I wasn't aware of wrong positions of ICSP-header, that's nasty. I need to check, but it should be 100% as the UNO.

Adding battery should be no issue if you take out the power-jumper. That will allow to connect battery plus to the middle pin keeping the regulators out of the circuit. I guess it would even be possible to add a 3rd pin to switch to battery.

In general the design is really great and flexible already. Minor improvements are possible but I'm already really happy with it.

Good work on the ICSP header and Xino connector, Joost. I considered doing something along those lines but the wiring of the ICSP header (on v1.5) does appear to be wrong, so I didn't bother. I'd definitely describe what you've done as a work around though. My work around is a prototyping shield with an ICSP header fitted to that.

Yes, it's a great design, but it still needs a bit of refinement. Improvements to it will mean more repeat sales for Ciseco, so I don't see any harm in asking for them.

The 5V/3.3V header you mentioned only feeds power to the MCU and the power LED - I wondered about that too. The 5V and 3.3V rails are connected to the output side of the regulators, so a jumper would be needed to break each one, I think, to allow the regulators to be fitted but bypassed for battery power.

Incidentally, Vin on the header socket, doesn't appear to be wired to anything. I guess that's left as an exercise for the buyer. I'd prefer that to be wired to the actual power source in use - either batteries if those are connected, or the input to the regulators.

I could do some track cutting and fit jumper blocks in the prototyping area to get the power connections how I want them (and I may do that), but it seems a shame to use up part of that area doing it.

(ignore this post - the forum engine got me again - told me it was too long but posted it twice)

I've popped changes in for the connectors so far, will look at the rest.

Putting 3v3 "into" the regulator (or the 5) will do no harm, you don't need jumpers to disconect them

Cool. Thanks, Miles.

The Arduino Uno datasheet advises against feeding power to the 5V or 3.3V line, so I thought damaging the regulators might be the reason. I've never seen any mention of a problem in voltage regulator datasheets, but they wouldn't be expecting you to do that, I guess.

arduino.cc/en/Main/ArduinoBoardUno : "Supplying voltage via the 5V or 3.3V pins bypasses the regulator, and can damage your board. We don't advise it."

Maybe they're talking about powering it from a source that isn't guaranteed to be 5V/3.3V or less?

Incidentally, your forum software has taken to telling me my posts are too long, but then posting them anyway (hence the double post yesterday). No matter how long it is, it tells me it's 52 letters and can only be 50 letters max. Maybe it only does it with Opera.

I bet they are being cautious because doubtlessly someone would hurl 5v (or more) into the 3v3 side and pop something.

That would make sense, yes.

I take it there'd only be a very small leakage current back through the regulators?

Never measured it, if I was looking for ultimate frugality I'd look not to use linear regs at all. Why not put you own jumper (or switch) on the proto area and desolder the output leg on the reg to the jumper and then back to the board?

I'll probably do that the first time I decide to run them via regulators. It would be nice to leave the whole of the prototyping area free for prototyping though.

It looks like there's a bit of room left around the regulators to add another jumper, but maybe not many people would care. I guess a lot of people are happy to commit to it being either battery powered or external powered anyway. I like things to be flexible, but that's just me.

On Xino #1, I fitted the caps and the 3V3 regulator but left off the 5V one. I have the MCU power jumper set to 5V, so the 3V3 regulator isn't in use - but I could use it if I needed to, say for an SD card shield. On Xino #2, I fitted the caps for the regulators but left both off for now. Both of them have only ever run on batteries or USB power, so far.


On a separate, but kind of related topic; would it be possible to offer a second type of ProtoX shield, that's all 0.1" spaced pad board? My hands aren't steady enough to solder SMT chips, so I'll never use those parts of them. A bit more usable area for the ham fisted would be great.