Pi vs BeagleBone-Black

I'd like to add another pro for the BeagleBoard Black.

With the exceptions of the integer real time processors PRU-ICSS (not sure at this point why that is), and the PowerVR GPU for

well known reasons, the AM3359 technical documentation from TI is excellent to the point of overwhelming. The Technical Reference

Manual is over 4000 pages. No I did not accidentally add any zeros !

Gary Stewart wrote:

 

With the exceptions of the integer real time processors PRU-ICSS (not sure at this point why that is), and the PowerVR GPU for well known reasons, the AM3359 technical documentation from TI is excellent to the point of overwhelming.

You're right about the proprietary GPU, that seems to be an endemic problem for open source in the industry.  It's not true for the PRU-ICSS though.

The PRU-ICSS is fully documented in the Technical Reference Manual SPRUH73C, with the entirety of chapter 4 (250 pages) devoted to it.  Also, there is a full package of PRU-related materials on Github, including more documentation and source code of the PRU's PASM assembler, a Linux loader, demos, etc.  I've even checked that the assembler compiles and it does.

The BeagleBone materials on Github are at https://github.com/beagleboard/am335x_pru_package

The PRU has been used successfully in quite a number of projects as a quick web search shows, and this long predates the BeagleBone Black since the original BeagleBone uses a slightly different version of the same AM3359 SoC.

Morgaine.

Addendum: Repeating the link to TI's wiki pages on PRU which I gave in my first post on this thread, in case it was missed when looking for docs.  There is a developers' link at the bottom of that first page.

Luc, Mark and Ervin, I agree completely about the pointless digression into realtime Linux.  That's why I didn't respond to the latest salvo, it's clearly a non-productive argument, so I ended the interchange unilaterally.  The merits or otherwise of realtime Linux are entirely irrelevant to the discussion about BBB versus Pi.  I tried to end it through reasoned discussion, but that failed.  Sorry.

In contrast, the BBB's PRUs are entirely relevant in the comparison, because it's a salient built-in feature of the BeagleBones and is so powerful that it has front-page bullet points on beagleboard.org's BBB page.  It's clear that they rate it highly, and not discussing it in a comparison with Pi would be remiss.

Also, let's not forget that even Eben Upton has publicly expressed support for the idea of coupling the Pi to an Arduino.  He's an engineer, and he knows full well that the gains in interface expansion and in realtime performance are really quite enormous when you combine the two.  Even the Gertboard has a microcontroller on-board, and despite not being an RPF product, it certainly has their blessing.

Well, because of its PRUs, the BBB requires no additional microcontroller to achieve the same kind of gains in interface expansion and realtime performance, so this enters very strongly into the comparison.  Pi can handle a small amount of interfacing without additional hardware, whereas BBB can handle a lot more.  Pi can satisfy very very weak realtime requirements with its standard kernel, whereas BBB can meet very hard realtime constraints with its standard kernel because it has a couple of PRUs that are dedicated to I/O.  For ambitious applications, that's a very big deal.

PS. This was about one feature only, where BBB happens have superior functionality.  Both boards do of course have both pros and cons, that's very clear, and it means that there is no "best board".  There is only "best board for your particular requirements", and so the answer will vary with the person.

Morgaine.

> OTOH, for video RasPi's media processor is probably better.  Like Morgaine, I have no need for it so it's not an advantage.

I think the details are still unclear about the BBB's usability for home theatre.

Apparently it mainly uses the cpu for mpeg decoding.  So does that mean that VLC

will be usable (unlike on the RPi where only omxplayer is hardware accelerated?)

It seems to me it is a bit unfair comparing TI's second generation BB to the RPF's

first generation product.  The RPi's big advantage now is that it is in mass production,

but the BBB is just announced and temporarily out of stock, with no clear idea of how

fast production can be ramped.  We have yet to hear when the RPi's educational release

will be or what it will include, but release 3.0 and/or 2nd generation is said to be coming.

I think it's noteworthy that the BBB is FCC/CE certified for sale to residential users,

but the current RPi as far as I know is not.  I think it's also noteworthy that the BBB

claims to support the Microsoft wireless 800 keyboard.  I think it's noteworthy that the

Fedora ARM folks support the BB directly, rather than indirectly through Seneca as a Remix.

coder27 wrote:

 

I think the details are still unclear about the BBB's usability for home theatre.

How welll it will perform in that role remains to be seen, but one thing is absolutely crystal clear.  It was not designed for that purpose, so if it works well as a media centre it will be as a lucky side effect of providing a working X11 desktop or Arduino UI. (*)

I've now read about half of the BBB System Reference Manual, and they make it abundantly clear that the board was developed to support engineers, technical enthusiasts, makers, and educators+students.  Reading between the lines, and from interacting with the BB community directly, there is considerable {concern,hostility,apathy} towards those that jumped on the Pi educational bandwagon purely because they wanted a cheap media centre.  The views vary of course, but I think it's safe to say that nobody considers the BBB to be a media centre platform, even if it works.

That area still belongs entirely to the Pi, and any competition for media centre eyeballs is unlikely to be coming from the BB stable.

Morgaine.

(*) PS. Lucky side effects are not impossible.  BBB has been shown running Quake 3.

> if it works well as a media centre it will be as a lucky side effect of providing a working X11 desktop or Arduino UI. (*)

Or perhaps as a lucky side effect of supporting Android with Flash and/or html5.

The RPF actively encouraged media centre users, and I think they account for

a significant fraction of sales.  I think a lot of folks justify the purchase by saying

"I'll buy it to learn programming, and if that doesn't work out, I can still use it as a

media center."  So quite a successful sales tactic.

Morgaine Dinova wrote:

 

coder27 wrote:

 

I think the details are still unclear about the BBB's usability for home theatre.

 

How welll it will perform in that role remains to be seen, but one thing is absolutely crystal clear.  It was not designed for that purpose, so if it works well as a media centre it will be as a lucky side effect of providing a working X11 desktop or Arduino UI. (*)

 

I've now read about half of the BBB System Reference Manual, and they make it abundantly clear that the board was developed to support engineers, technical enthusiasts, makers, and educators+students.  Reading between the lines, and from interacting with the BB community directly, there is considerable {concern,hostility,apathy} towards those that jumped on the Pi educational bandwagon purely because they wanted a cheap media centre.  The views vary of course, but I think it's safe to say that nobody considers the BBB to be a media centre platform, even if it works.

 

That area still belongs entirely to the Pi, and any competition for media centre eyeballs is unlikely to be coming from the BB stable.

 

Morgaine.

 

(*) PS. Lucky side effects are not impossible.  BBB has been shown running Quake 3.

BBone has a powerful 3D graphics engine.  I don't know how it compares to RasPi -- I hear opinions about RasPi's being better but haven't seen any independent benchmarks.  So BBone is great for synthesizing graphical images.  Now for decoding purchased (or not) video content or video encoding, it's probably true that RasPi is better, but "those frills cost money" -- you may have to purchase licenses for the RasPi Codecs.

Regarding {concern,hostility,apathy}, my own feeling is mostly "pity" as in "here you have a pretty decent GNU/Linuix box and you just want to watch silly videos?"  My chief annoyance with "RasPi as naked Roku2" users is that they made it really hard to get a RasPi when it first came out.  OTOH, those "other users" help drive the price down, which benefits everyone in the long run.  As a free-as-in-freedom proponent, I want to be able to use hardware I buy for whatever I want so I must support the right for others to do the same.

John Beetem wrote:

 

Regarding {concern,hostility,apathy}, my own feeling is mostly "pity" as in "here you have a pretty decent GNU/Linuix box and you just want to watch silly videos?"

I haven't detected "pity", so I'll add yours to the list.

I have noticed a fair bit of ridicule too, although I don't think any of the above 4 accounts for it.  It seems to stem from simple peergroup reinforcement, blowing raspberries at "that other lot" not for any solid reasons but to sound cool in company.  Unfortunately IRC seems to encourage it.  I think it's softened a bit now compared to 9-12 months ago, possibly because a large number of BB owners now have Pi boards too.

I like all the boards, they all have a specific niche where they shine.  Pi-B's niche is narrowing now though.

Morgaine Dinova wrote:

 

Pi-B's niche is narrowing now though.

Indubitably.  When BBone was US$89 plus US$50 for a DVI-D card the combination was 4X a RasPi model B.  Now it's just 30% more (US$45 versus US$35).  If you're a teenager, that's a lot fewer cars to wash or lawns to mow.  Teen geeks should charge more for resetting digital clocks after power failures.

IMO BBone Black is the clear winner for a maker.  RasPi is IMO still better for a newbie mostly interested in software or very simple hardware.

John Beetem wrote:

 

When BBone was US$89 plus US$50 for a DVI-D card the combination was 4X a RasPi model B.  Now it's just 30% more (US$45 versus US$35).

For the basic package prices, sure.  But these prices don't reflect the actual investment needed before you can use the boards.  For BBB you need nothing more at all if you use it tethered to a PC, because it has the O/S preloaded in the eMMC device, comes with a USB cable, and appears as a USB storage device as well as being powered through the cable.  Pull it out of the box, plug it in, it works --- instant gratification.

The Pi doesn't come with any leads, and can't be used in that tethered mode, and doesn't come with an SD card anyway, so you can't use it in BBB's "minimum investment" mode.  To compare working systems fairly, you have to add to the price of the Pi a PSU (or at least a USB lead) and an SD card, and the gratification is not instant because the newbie "hurdle" of writing the SD card still has to be overcome.  Viewed that way, the Pi model B isn't cheaper than the BBB, it's either the same or more expensive, depending on the quality of accessories you buy.  For beginners, it's also a lot more hassle, and that's assuming that the  PSU and SD card that the newbie buys will actually work with the idiosyncratic little board, which is far from certain.

So, I don't think that "cheaper" is actually correct for Pi unless viewed very narrowly, since it won't run as supplied.  And "easier" is debateable too.  Pi is the clear leader as a media centre.  In all other applications, it now has one direct and very able competitor, as well as a swarm of others just outside its price niche.

I like all the boards, they all have a specific niche where they shine.  Pi-B's niche is narrowing now though.

The intended R-Pi market was always very narrowly defined (very low cost computer used to teach kids about computers). The RPF vastly underestimated its

"geek appeal" and this is the primary reason sales took off to levels well beyond the RPFs original expectations. I don't think that will last but due to that popularity

it has actually increased its niche to cover several other areas, using it HD video applications is probably one that it is better suited for. The  availability of a HD

video camea will also help here. Its success and fierce competition in the SOC markets will probably create direct competitors and it will have to keep improving

to stay ahead of them. Something I'm not sure a non-profit organization can do.

The BB Black is aimed at completely different market. It is a more general purpose platform with a large number of multi-purpose I/O pins available and aimed

primarily at computer professionals. Its more general purpose nature give it a much wider range of possible applications right from the start. There is a lot of hardware

crossover between the two but this is true on almost every modern ARM SOCs since they almost all include a long list of the same features.

From John Beetum:

BBone has a powerful 3D graphics engine.  I don't know how it compares to RasPi -- I hear opinions about RasPi's being better but haven't seen any independent benchmarks.  So BBone is great for synthesizing graphical images.  Now for decoding purchased (or not) video content or video encoding, it's probably true that RasPi is better, but "those frills cost money" -- you may have to purchase licenses for the RasPi Codecs.

It is definitely much better than the GPU in the R-Pi. The main drawback I see for the BB Black as far as video goes is the 16 bit memory data bus vs 32 bit for the Pi. Both share

the RAM with the ARM core and the GPU, and video applications require RAM access for display as well as display data processing so it is hard to see how this would not have

a negative impact on the BB Black in most video applications. I pretty sure the R-Pi can also play Quake Three but I'm not sure what market this helps either of them with.

Does TI already have a license for the codecs ? Otherwise they would have to be bought to use them for the BB Black too.

> The intended R-Pi market was always very narrowly defined (very low cost computer used to teach kids about computers).

Education was the stated goal of the RPF, but not necessarily their marketing focus prior to

the yet-to-be-released educational release.  I see a lot more marketing effort focused on

Maker Faire venues than educational venues.   Early on, they hired an educational person,

but quickly let her go without a replacement until recently.

> The main drawback I see for the BB Black as far as video goes is the 16 bit memory data bus vs 32 bit for the Pi.

I think you also need to consider memory caches and data paths.

On the RPi, the cpu has to go through the gpu to access memory and cache.

I suspect the BBB has a better caching system.   There are memory benchmarks

that might be useful, such as

http://lmbench.sourceforge.net/

> The intended R-Pi market was always very narrowly defined (very low cost computer used to teach kids about computers).

Education was the stated goal of the RPF, but not necessarily their marketing focus prior to

the yet-to-be-released educational release.  I see a lot more marketing effort focused on

Maker Faire venues than educational venues.   Early on, they hired an educational person,

but quickly let her go without a replacement until recently.

> The main drawback I see for the BB Black as far as video goes is the 16 bit memory data bus vs 32 bit for the Pi.

I think you also need to consider memory caches and data paths.

On the RPi, the cpu has to go through the gpu to access memory and cache.

I suspect the BBB has a better caching system.   There are memory benchmarks

that might be useful, such as

http://lmbench.sourceforge.net/

coder27 wrote:

> The intended R-Pi market was always very narrowly defined (very low cost computer used to teach kids about computers).

Education was the stated goal of the RPF, but not necessarily their marketing focus prior to

the yet-to-be-released educational release.  I see a lot more marketing effort focused on

Maker Faire venues than educational venues.   Early on, they hired an educational person,

but quickly let her go without a replacement until recently.

> The main drawback I see for the BB Black as far as video goes is the 16 bit memory data bus vs 32 bit for the Pi.

I think you also need to consider memory caches and data paths.

On the RPi, the cpu has to go through the gpu to access memory and cache.

I suspect the BBB has a better caching system.   There are memory benchmarks

that might be useful, such as

The focus still seems to pretty heavy on education however given the new opportunities that opened up, things changed. I still see a heavy interest

from the RPF in education though. They just seem to be relying more on outside help and they always said that they wanted that too.

I do consider caches and data paths but I assume they both have video and CPU caches so I see no advantage either way there. Displaying video

must have top priority otherwise the display will have artifacts and that would not do at all. For this reason it makes sense that the memory path to

the CPU in the Pi runs through the video section first. Sooner or later (and probably fairly often) there is going to a miss in all caches and filling sets

of tag lines (video first, always) through a 16 bit data path is a major bottleneck. Even with the 32 bit data path I'm fairly confident that this is a major

reason as to why the Pi seems sluggish most of the time even when it is overclocked to 1 GHz. I don't see how a 16 bit data path can be made to

improve that.

I will never been a big fan of the CPU and video sharing memory on motherboards. For low cost solutions using SOC's it makes more sense but at

a (literally) noticeable cost.