USB discussions getting a bit heated

I gather that 8 endpoints is a hardware limit because a Foundation or Broadcom person said that they found it in the Verilog for the SoC's USB controller, IIRC.  The interrupt rate issue is completely separate from that.

Eeewww... a limitation that's hard coded into silicon is going to be difficult   It's what comes of never being designed for what it's being asked to do. 

The model A with SPI ethernet is looking more and  more appealing.   However, with the pragmatic hat on for a moment, if the interrupt rate problem can be resolved it still mostly meets the design goal for a small educational device with wired ethernet, mouse & keyboard. I say mostly as there's a lot to be said for being able to save stuff to a usb key as well as the sd-card, but still, it's not completely fatal - inconvenient yes.

It is going to be really hard, making USB OTG work as a "host" if you excuse my French is a "***" ...

I found some documentation from Synopsys (http://www.synopsys.com/dw/ipdir.php?ds=dwc_usb_2_0_hs_otg) but didn't have time yet to even browse through it.

-J

The model A with SPI ethernet is looking more and  more appealing.   However, with the pragmatic hat on for a moment, if the interrupt rate problem can be resolved it still mostly meets the design goal for a small educational device with wired ethernet, mouse & keyboard. I say mostly as there's a lot to be said for being able to save stuff to a usb key as well as the sd-card, but still, it's not completely fatal - inconvenient yes.

Hmmm, that would be some interesting project to try, as far as I remember there are some Linux drivers for the Microchip standalone Ethernet controllers, obviously don't expect to power the thing from the regular 3V3 power supply.

I used to produce this board based on the ENC424J600

I'll put on my to-do list of things to try in my protoboard setup... Good idea selsinork

-J

selsinork + jamodio:  TCP offload and USB offload beckons, as you are both suggesting.

It's certainly an engineering solution to the problem, but the trouble is, what's left of the Pi if you have to add those externally?  Just a standalone multimedia chip with SD card and low-end ARM.  It's no longer appealing for $35, and doesn't even make any sense in a networked world.

Ohh no, it is just for experimenting. I'd rather put more time/money on Beagle or Panda boards, I'm waiting for the guys from Olimex that said their board should be about ready in September.

If RPF does not come up with a decent solution which may require to dig deep into the design, besides being an interesting gadget to tinker with and some stuff that can be donde with model A, asuming you can hookup a keyboard and a mouse that works with an external hub, IMHO the thing is dead.

-J

It's no longer appealing for $35, and doesn't even make any sense in a networked world.

Ok, but... Alternatives ?   With reliable, even if slow, ethernet it still works for me. If we offload anything much then the model A is obviously a better starting point.

If usb can be fixed - within limits of the silicon - that's better. But as you keep saying, it needs to be reliable and 'just work'.

obviously don't expect to power the thing from the regular 3V3 power supply.

What, no 1.8v version that I can power from the lan9512 ? 

Nice looking board..  I know it'll work - Chris Boot and Simon Arlott were using them along with sd-card on spi during their 3.5 kernel efforts.

Hmmm another alternative would be, based on something close to the current design but fixing the power supply issues and other things that Pete may have on the list, os for the distributors to bundle the board with a power supply, keyboard and mouse that were proven towork at an attractive price, and it can still be a low cost platform for education.

But a that time, I'd guess that some Linux distro would be running on the APC board, yes sans GPIO now and a bigger board but you get other features ...

-J

selsinork wrote:

 

Ok, but... Alternatives ?

Zillions of alternatives, as long as one is free to choose designs and components in response to functional requirements.  Unfortunately RPF is driven more by politics and facial egg than by engineering so it's academic, but anyway ....

The simplest solution is to use the most appropriate SoC or SoCs for Pi version 2.  If the BCM2835 is still the best multimedia device available, fine, use it, but it's crap for USB, networking, and computing, so put another SoC next to it to do those functions better.

This is no theory, I'm looking at the basis of a solution here on my table.  Since the BeagleBone's TI AM3358/9 SoC costs $5 in volume, throw away the Pi's LAN9512 and add the TI SoC instead.  That would give the Pi a more powerful Cortex-A8, on-chip Ethernet MAC, two on-chip USB (one host and one OTG I think), and a zillion hardware ways of interfacing to the BCM2835 for multimedia.

It's totally pointless even thinking about it though.  RPF has all the mobility of a block of granite entombed in an ancient lava flow.

Morgaine.

If the BCM2835 is still the best multimedia device available, fine, use it,

I'm still uncertain how that matters. Right now all that potential still hasn't found an outlet. Lack of codecs prevents serious multimedia use and lack of accelerated X driver means you get no benefit elsewhere. Those things are being worked on, but without a timetable. So it could still be the best unused multimedia device in 5 years.

Since the BeagleBone's TI AM3358/9 SoC costs $5 in volume, throw away the LAN9512 and add the TI SoC instead.

Hmm. I'd be tempted to throw away much more.  I know it's been commented on before, but if that thing is $5 why hasn't someone done something like the Pi at equivalent cost using it ?  Or alternatively is the BCM2835 available to RPF at significantly less ?