tufty wrote:This is part of why the first 10k were intended to be developer boards - to knock out the remaining hardware and software bugs. IMO it's probably time to bring out a revised board, go back to switchmode for the regulators, and knock the stupid USB charger idea on the head. Before half a million buggy boards finish hitting the street.
Agreed. But if I had ownership of the issue, had to find a solution, I'd say there is no easy solution beyond documenting the (unintended pun) current characteristics of the board and potential issues with it.
It doesn't matter if the solution is easy or not. The problem exists, and it's going to be a killer for getting devices into schools, even if the wailing of hundreds of thousands of new, and now disappointed, owners doesn't do that first.
The idea behind the USB PSU was that pretty much everyone has one, those that don't can easily and cheaply get one, and that they can be relied on to provide enough juice for the Pi. The problem with that is that a large proportion of USB chargers (even OEM ones shipped with curent-model, although "basic", smartphones, if my quick check at the phone shop is anything to go by) do not put out enough juice for the Pi; of those that do, it appears to be a lottery as to whether they push out enough, and well enough regulated, juice for Pi + a couple of low-power USB devices. FWIW, in my quick straw poll at the phone shop, before the bloke got bored of showing me chargers, out of 12 OEM and 3 aftermarket chargers, I only found 3 OEM chargers that were labelled as putting out more than 500mA and only one aftermarket one.
What this means for schools is that they will have to shell out for name brand (or at least have to pay name brand prices) for PSUs. This was probably the case anyway, except that, instead of getting cheap, "throwaway" units, they are going to have to spend potentially more than the Pi itself on a PSU (which, of course, will charge little Johnny's smartphone faster than the one he has at home, and may well "grow legs")
USB devices are also a problem. I don't personally have a single USB keyboard that I have any confidence will work with a Pi (when I eventually get one). Every USB keyboard I have has a built-in hub. Hell, every mouse
I have asks for 100mA (with the possible exception of the old logitech ball mouse that got retired because its rollers were jammed). It doesn't matter for me, because I don't anticipate using any USB devices on the Pi for a very long time.
What this means for schools is that they may well have to shell out either for new keyboards (and maybe mice), or for powered USB hubs (which don't appear to be the universal panacea to USB issues we were led to believe either). But they won't know for sure until after they have purchased X Pis and found that their existing kit doesn't work with it. Noice. This also means that the idea of sending little Johnny and Janet home with a Pi in their respective pockets is pretty much out of the question, unless you also hand them a "guaranteed in spec" charger, keyboard and mouse (or hub), because you can't guarantee that, even if they have something that nominally "should work" at home, it's actually in spec.
USB devices as simple as keyboards and mice should "just work" when plugged directly into the Pi. As it stands, it appears that the Pi is very broken for a significant number of people. And the longer we wait, the more significant that number of people is going to be.
"Raspberry Pi : An ARM GNU/Linux box for $25. If you're lucky, it might even work!" isn't much of a slogan