Interesting "Competitors" for the Raspberry Pi

The parallela sounds and looks cool but we are talking about a major project that includes sillicon rebake and that probably is 6-12months away from mass production.

Meanwhile while there are other developments that are not exactly comparable to the R-Pi, they are slowly but steady making progress, like the OLinuXino boards from Olimex. I'm testing both the micro and maxi using the Freescale iMX233 application processor SoC (fully documented by the way,) waiting for the A13 one and they also have under development one using the A10. The iMX233 Maxi uses also the LAN9512 and I didn't find any issues with it yet (and BTW the connectors are properly aligned and it has a nice swtiching power supply, the board is slightly bigger than the R-pi, no HDMI/VGA tough.)

I also recently got a TI AM335x Starter Kit, you will start to see more stuff based on the AM335x and TI will get more agressive to dettach the OMAP from some applications and put it on boards similar to the R-Pi.

Still the R-pi continues to be a good idea, unfortunatelly with an associated plan badly executed and with more focus on hype and promotion than really make it a strong and solid "product" with the participation of a community that is eager and able to contribute.

No schematics, no Gerbers, major concern is "cloning" .... I'd not clone something that is not working properly ...

-J

At least it looks like Olimex is taking the problems from people using their boards seriously.

Their Forum is an example of what a forum should be like.

The supply dip when you connect an usb device is a known fact. It might be hard to notice it on a scope, unless you have a good memory scope and are able to trigger it properly. The issue happens more frequently on the newer boards with the usb polyfuses removed. If you look at the Pi schematics, there aren't much buffer capacitors on the 5V supply rail. (just 1 small capacitor). I guess we get what we payed for.

It looks like a lot of the Pi usb issues are caused by timing.

As linux isn't a real time OS, and as stated before that the cpu can become heavy loaded, I doubt they will ever be able to fully fix the issue.

Besides the usb, there are other dissapointing things. One mentionned already is the fact that X11 isn't hardware accelerated.

Another one is the poor quality of the analog audio output. A third one is the fact that you need to properly shutdown the system to avoid sd card corruption. This makes it difficult to use the Pi as an embedded solution. A fourth one is the critical power requirement of the board.

Some of those can be resolved, but all solutions make your cheap solution (not so cheap) anymore.

I know it's a little off topic, but these points are worth checking when seeking for "Competitors" and might rectify a higher price.

Jonathan Garrish wrote:

 

1) The hardware: ARM - not so much a platform as a sprawl. It's overwhelmingly used to power consumer devices, so maturity, backward compatibility, future security and all the other stuff that a community needs to get a piece of hardware to do something interesting just isn't there. Your chosen software may not even have an ARM port. Obviously this is no barrier for the dedicated geek with access to source code, but it's a faff. The fact that ARM is such a mess certainly doesn't encourage software developers to embrace it...

 

2) The software: ... but as ARM is so splintered I really don't see the situation changing any time soon for consumers who want an ARM P.C. for general duties and want it to work out of the box without having to constantly *** around in terminal.

ARM has an interesting history.  As I recall it, the previous time ARM had a presence in general-purpose computing was with the Acorn, back when ARM stood for Acorn RISC Machine and the ARM2 processor was indeed RISC.  Then they made it big in the Apple Newton, which I don't think of as a general-purpose computer.  At this point they became Advanced RISC Machines, reflecting advances (and increased complexity) in the architecture.  They had a corporate mind-set of low power consumption, so when a 32-bit processor was needed for cell phones ARM was the obvious choice.  Again, we're talking embedded applications, not general-purpose computers.

In embedded applications you're running built-in software, so the problems with multiple versions of ARM aren't so serious.  You know what version of ARM the product has, and you can compile and optimize for that architecture.  Since every one of your 1 million users are going to be running that same software, it's worth buying the best ARM compiler you can and worth spending the time to use performance-tuning software to find the bottlenecks and rewrite them in ASM.  I've heard that GCC does a poor job with ARM architecture by not making effective use of conditional execution of instructions.  Instead it uses conditional branches, which can destroy performance in a processor with long pipelines.

Now we're seeing ARM once again being used as a general-purpose computer, using inexpensive compilers that probably haven't been tuned for it.  However, with 0.5 million RasPis out there and 1.0 million estimated for the first year of sales, there's finally an incentive to get in there and make decent ARM code generators.  So I don't see compiling for ARM as a long-term problem.

ARM has a huge for a laptop application: very low power consumption so long battery life.  I've never bought an x86 laptop because IMO it's silly to use a laptop that warms your lap, or worse, needs a fan pad.  I just put together my first laptop: a RasPi with Atrix Lapdock   ARMs are fast enough for decent laptop/desktop performance, as long as they have enough memory for your target applications and decent mass storage performance.  The software will catch up.

Morgaine Dinova wrote:

 

George, it's no different to hobbiest suppliers often providing a semi-populated board containing only the SMT components for the design already placed, in order to support those enthusiasts who like to construct but for whom soldering SMT is difficult.  There are many such people, even today with the wide presence of SMT.

 

Likewise, soldering BGA would be problematic for the majority of hardware enthusiasts, so providing the BGA part on a plugin module would play a similar role.  The rest of the board would be constructable by the majority of enthusiasts using their more common building skills, which does not include handling BGA.

I don't mind SMT, as long as lead pitch isn't below 1 mm.  I really like the EOMA-68 form factor, which uses a PCMCIA 68-pin connector.  Then you design and build a base board with your custom thingummies, and plug in the EOMA module to provide computing.  Next year, you plug in the next generation module with twice the computing, keeping your base board.

I like SODIMM connectors except for the fine pitch, because they have reliable high-pressure contacts.  I might be convinced to use an SODIMM-144 connector (0.8 mm pitch), but fuggeddabout an SODIMM-200 with 0.6 mm pitch.

John Beetem wrote:

 

I like SODIMM connectors except for the fine pitch, because they have reliable high-pressure contacts.  I might be convinced to use an SODIMM-144 connector (0.8 mm pitch), but fuggeddabout an SODIMM-200 with 0.6 mm pitch.

There are already a few companies using the SO-DIMM-200 and it's mainly used because you almost need all of those pins to get all of the signals out off of the processor. They aren't that bad to solder because most of them have mounting feet which lock there posistion down on the board and then you only need to add solder. But if "we" went this route, wouldn't you want to provide a low cost baseboard that brings all the signals out anyways? If you're trying to reach economy of scale, what percentage of people are really going to care that they might not be able to solder their own connector? Did millions of people not buy the RPi because they couldn't solder the parts themselves? Or for that matter, how many people are even building their own Arduino boards even though you could? If you price a board at ~$50 I don't think too many people are going to go, oh, that's too much, I could solder those parts down and save $5. Look at what TI has done with their launchpad boards, how can you beat a $5 development board? Let people buy the base and fiddle with their own stuff.

George Ioakimedes wrote:

 

John Beetem wrote:

 

I like SODIMM connectors except for the fine pitch, because they have reliable high-pressure contacts.  I might be convinced to use an SODIMM-144 connector (0.8 mm pitch), but fuggeddabout an SODIMM-200 with 0.6 mm pitch.

 

There are already a few companies using the SO-DIMM-200 and it's mainly used because you almost need all of those pins to get all of the signals out off of the processor. They aren't that bad to solder because most of them have mounting feet which lock there posistion down on the board and then you only need to add solder. But if "we" went this route, wouldn't you want to provide a low cost baseboard that brings all the signals out anyways? If you're trying to reach economy of scale, what percentage of people are really going to care that they might not be able to solder their own connector? Did millions of people not buy the RPi because they couldn't solder the parts themselves? Or for that matter, how many people are even building their own Arduino boards even though you could? If you price a board at ~$50 I don't think too many people are going to go, oh, that's too much, I could solder those parts down and save $5. Look at what TI has done with their launchpad boards, how can you beat a $5 development board? Let people buy the base and fiddle with their own stuff.

I'm not interested in soldering to save money.  That concept went away a few years before Heathkit went out of business.  The reason I'm interested in 1mm+ pitch is so I can create custom baseboards with specialized interfaces and assemble them myself, and then plug in a module that has all the fine pitch and BGA components, such as Variscite SODIMM-200 or Gumstix.  However, both of those require fine-pitch connectors.  Now, it may be that in addition to low-cost PCBs you can find places that will also solder down a few fine-pitch components as well.  Unless such exist, I either need 1mm+ pins or I'll just buy a BeagleBone or Cubieboard or ST Discovery or whatever and make the case tall enough to fit it.

John Beetem wrote:

 

I really like the EOMA-68 form factor, which uses a PCMCIA 68-pin connector.  Then you design and build a base board with your custom thingummies, and plug in the EOMA module to provide computing.  Next year, you plug in the next generation module with twice the computing, keeping your base board.

Me too.  What's more, it's very appealing for making clusters, since such a large number of vertically-oriented EOMA-68 modules can be placed side by aside in a horizontal rack.

This is the age of multicore, allegedly.  We should not be building general purpose computers of any ilk with single CPUs anymore, it will count against our karma at the pearly gates.

Morgaine Dinova wrote:

 

Me too.  What's more, it's very appealing for making clusters, since such a large number of vertically-oriented EOMA-68 modules can be placed side by aside in a horizontal rack.

 

This is the age of multicore, allegedly.  We should not be building general purpose computers of any ilk with single CPUs anymore, it will count against our karma at the pearly gates.

Yes, a EOMA-68 cluster sounds great!  It would look something like the inside of the HAL-9000 in 2001: A Space Odyssey

The lesson of multicore: if RasPi had a multicore SoC, one core could handle USB properly and one could run X server full time, eliminating two serious performance issues.

I totally agree with a multicore processor but I fail to see how you think 68 pins is near enough. If we're considering the embedded space then you can't ignore direct connection to an LCD which means 24 pins just for RGB, then there's Ethernet, USB, SPI, PWM, and on and on. You guys were complaining about wanting an easy method to solder devices but it's specialized equipment to weld those PCMCIA clam shells together.

George Ioakimedes wrote:

 

I totally agree with a multicore processor but I fail to see how you think 68 pins is near enough. If we're considering the embedded space then you can't ignore direct connection to an LCD which means 24 pins just for RGB, then there's Ethernet, USB, SPI, PWM, and on and on. You guys were complaining about wanting an easy method to solder devices but it's specialized equipment to weld those PCMCIA clam shells together.

The pincount on a processor module within a multiprocessing cluster isn't really related to all those things you mention, for a variety of interrelated reasons:

• Memory should be local to each processor module because global memory doesn't scale beyond very small processor numbers.
• I/O isn't done on processor modules because all processors need to access it symmetrically without bothering other processors.
• Realtime I/O should be handled by dedicated microcontrollers, not by a  *nix kernel which is very bad at it.
• Microcontrollers provide large numbers of GPIOs and are dirt cheap, so microcontroller-based I/O modules should do all the I/O.
• Communication between processor modules and I/O modules is best done as high-speed serial messaging.
• Serial message communication doesn't need a lot of pins and is topologically very flexible.  Remember the transputer.

I suspect we have completely different designs in mind and hence we are talking about different things.

Morgaine.

I really like the EOMA-68 form factor, which uses a PCMCIA 68-pin connector.

As someone who used to have to solder pcmcia connectors on some early Thinkpads - 386 vintage, I know I never want to have to do it again.  Besides, if you look in a modern laptop that still has pcmcia the pitch has reduced down to the sub 1mm problem you entioned in another post.

It's certainly one thing I don't like - fine pitch connectors. From the experimenters perspective you either need easily available, cheap, and can be hand soldered without requiring solder paste hot air and/or liquid flux.  While those requirements won't put some of us off, they significantly reduce the accessibility for most people.

Or else you need a cheaply available adapter board to go from the fine pitch connector to something more useable - and a bigger case

selsinork wrote:

 

Or else you need a cheaply available adapter board to go from the fine pitch connector to something more useable - and a bigger case

Well I have no shortage of DIN41612 connectors.

More seriously, what are the major options in high pinout connectors these days without dropping below 0.1" pitch?  While DIN41612 is still available and viable, I assume that there are more modern alternatives, not to mention cheaper as well.  "Industrial strength" is probably not needed here.

selsinork wrote:

 

Or else you need a cheaply available adapter board to go from the fine pitch connector to something more useable - and a bigger case

Well I have no shortage of DIN41612 connectors.

More seriously, what are the major options in high pinout connectors these days without dropping below 0.1" pitch?  While DIN41612 is still available and viable, I assume that there are more modern alternatives, not to mention cheaper as well.  "Industrial strength" is probably not needed here.

More seriously, what are the major options in high pinout connectors these days without dropping below 0.1" pitch? 

I really don't know a good answer to that. Number of needed connections vs size of the connector is always going to be an issue. Need 200 connections and your DIN41612 connectors make for a huge board.  OTOH, I recently mistakenly ordered some 1.27mm pin headers instead of 2.54mm recently, but they're tiny, fragile and most likely need a professionally produced TPH multi-layer PCB to be able to route a lot of signals away from the connector.

Morgaine Dinova wrote:

 

More seriously, what are the major options in high pinout connectors these days without dropping below 0.1" pitch?  While DIN41612 is still available and viable, I assume that there are more modern alternatives, not to mention cheaper as well.  "Industrial strength" is probably not needed here.

I think Cubieboard does a good job with their connectors.  They have two 48-pin 2mm pitch connectors, so it's easy to make a base board with low-profile Samtec 2mm sockets (e.g., CLT and SMM series).  Not as low profile as EOMA-68 but you do get 96 pins.

http://linux-sunxi.org/Cubieboard