Raspberry Pi - Hardware Flaws and Fixups?

It is not an issue of liking it or not, I remember reading numerous reports (you can google for it) of customers complaining about issues with the microUSB connector in several products, such as the Nokia N900, Nokia E7, HTC EVO, BlackBerry PB, etc. Some people even admit that is their fault when the connector is not lined up properly (ie. upside down) and by insisting and putting extra pressure the surface mount female jack gets removed from the pcb or if the traces are too thin they get cut due the mechanical stress.

About availablity of power supplies, nowadays you can find zillions like the one distributed with the Roku box which uses a standard DC jack, they sell them for $9.99, but you can find many other sources with a $5-$10 price range.

I agree with GizmoB73, not intended to be criticism, being the main target user school kids, anything that make the boards more reliable and child proof IMHO is a plus.

Didn't check, but in large volumes I'd also look at what is the cost difference between a decent DC jack and the microUSB.

The problem with micro USB is when you apply some vertical force on the plug,  a small force to the connector may produce a significant force on the tracks of the pcb, welding holds, but the tracks come off.

Generally, the design of housing will prevent it.

Hey GizmoB73,still connected, did you give up with the media player ?

Is XBMC ok ?

Did you get some help or info from the foundation about the low frame rate and the lack of sound ?

Maybe Pete has the solution.

It's certainly something I worried about.  The micro USB's are a bit of issue because they latch the connector in, and the amount of force you require to extract it is significant. The only problems I have had reported is when trying to extract they have used the electrolytic cap on the PSU input as a counter point to hold the board and broken that off. Interestingly they all still work perfectly - just look a little sad.

I deliberately chose one that had through hole anchor pins on it as I could see that the fully surface mount ones are (well to be blunt) - rubbish in terms of abuse withstand.  To mitigate against users trying to force the connector in upside down the part also has a solder land under the front of the connector which solders the formed body together and also to the board. We also chose an HDMI socket that had good through hole retaining pegs for similar reasons.

In terms of why we chose micro USB - simply the wide range of cheap phone charger that now exist and the standardisation of voltage supply spec that saves us another regulator.

Right call? - time will tell (still need to move that cap though)!

Cheers

Pete

Thanks for the follow up Pete. As you said time will tell, and hope you guys can sail smoothly through the compliance tests and put the boards on people's hands, that will really be the ultimate test.

Good call on the HDMI one, yes those cables can put a lot of tension on the connector.

Cheers

Jorge

I'd agree the 2.5mm jack is more robust, but it's a bit *too* common. My company's first product that used a 2.5mm jack, running on 5V and it ended up being bundled by some retailer with a completely different product that used the same jack but came with a 24 V supply(!) and you can guess the results. That quickly got fixed with a redesign but the protection circuit cost some money and board space.

Jacques, I am mobile at present with no access to the Pi.

I will try what I can when I return next week.  I have three Mede8ers around the house running from a NAS so the XBMC is an amusement, not something I really expect to be using.

Yes, I guess that one of the side effects of using USB connectors is that you have some guarantee that the input will be ~5V to meet the USB standard.

For some of the projects I've been working on lately I started using the TI SWIFT step down DC-DC converters, such as the TPS54231, it provides a wide input range and is highly efficient, obviously you need a source higher than 5V but I added a full bridge rectifier so you can get AC/DC input not worrying about polarity, but as you said it represents additional cost and board space.

I also asked Pete if they ever considered using a power management IC, I believe that Eben at some time mentioned that the plan was to use a buck regulator.

I know cost is a big issue, but there are some IC's that can take multiple power sources, include a LiPo charger and multiple outputs with protection.

Good job Pete, it seems that you have choosen the best USB connector.

Ready for a Mars mission

I do worry about the robustness of the micro-USB connector.  How many connect/disconnect cycles are they rated for?  Remember that the Rpi has no power switch, so the connector and its mounting area will inevitably suffer a lot of abuse.

According to http://en.wikipedia.org/wiki/USB#Mini_and_Micro_connectors, micro USB connectors are rated for 10,000 cycles, compared to 1500 for a standard size USB connector.  Personally, I find this dubious given how well some cheap cables adhere to standards, but if it's right you can plug and unplug your RasPi three times a day for 10 years :-)