The Future of Pyra's CPU


levi

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I think the tape you're looking at it not the heat conductive tape, it's an insulator to stop the CPU heating up the battery compartment. I'm not sure what the solution is to attach the CPU to the heat sink block that lives next to one of the USB type-A ports, but perhaps when you get a new board it might already be attached to it's specified radiator.
 
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levi

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You're in a dark maze. You can just make out exits to the North and East. A new compute module arrives and blocks your path!


This is worth posting because of the new form factor. No longer do the compute modules need a bulky SODIMM connector to be attached to another board, what they've gone for looks rather similar to the connectors used already to connect the Pyra CPU board to it's parent board, although the spacing it entirely different, so would require a redesign.

In terms of grunt, it's based around quad 1.5GHz 'little' 64-bit processors, so less efficient than the A15 cores in the Pyra although with four of them it might be worth playing with. It also offers OpenGLES3.x via a binary blob and various video decode options that might be worth considering. And of course, assuming this form factor isn't a flash in the pan, it could be interesting when the CM5 comes around, assuming that's an actual step ahead of what we already have in our Pyras.

TLDR; have a video:
 

levi

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Yeah, though I wouldn't say it's worth it just for a Pi4 level of performance. Sure it's got some more graphics ability, but I wouldn't say it's enough to make it a saleable upgrade. What is important, however, or hopefully will be is that if they stick with this form factor for the Pi5 compute module and on, it might be worth playing around with this Pi4 computer module to be ready for that eventuality.
 

pyrat

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But isn't the RPi4 SOC (BCN2711) compromised by needing blobs to boot ? And how hard is the SOC to obtain anyway ? Or do you mean using the whole compute module ?

Anyway, I don't see how the compute module would help. Even if thermally and physically could fit (no idea), one would still need to adapt the connector to plug it to the mainboard, no ?
Is that feasible ? cheap?

Rpi4 CM alone is 40x55x5-7 mm That'd be wider than the Pyra CPU board ? Would there be place for connectors ?

I don't see it
 

Robert Taylor

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Great point. Looks like ED was ahead of the curve on a number of levels. Pyrat, I think it is fairly obvious that it was a post of the direction that some components are taking and how they look a lot like what ED has already accomplished. The idea is that perhaps in the future something in this genral direction might pop up that we can use / adapth.
 

TrashyMG

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But isn't the RPi4 SOC (BCN2711) compromised by needing blobs to boot ? And how hard is the SOC to obtain anyway ? Or do you mean using the whole compute module ?

Anyway, I don't see how the compute module would help. Even if thermally and physically could fit (no idea), one would still need to adapt the connector to plug it to the mainboard, no ?
Is that feasible ? cheap?

Rpi4 CM alone is 40x55x5-7 mm That'd be wider than the Pyra CPU board ? Would there be place for connectors ?

I don't see it
I think he means using the whole compute module, yes it would be bigger than the Pyra CPU board... still it would likely need an entirely new main board to work.
 

levi

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I don't have the dimensions of the Pyra CPU board, but the entire Pyra is 139mm wide according to wikipedia. I doubt the CPU board currently specified is smaller than 55mm although I couldn't be sure.

You'd still need a main board which has all the extra modules and connectors on. Modify that board to fit the placement of the connectors on the Pi4CM and hopefully future more applicable upgrades.

Yes, it needs binary blobs, but then so does the OMAP5 based CPU board; not to boot, but for graphics at the very least. But it simplified development costs considerably, and as documented in the video I linked should also reduce compliance costs. That fact you can't even boot the board without the use of blobs might limit the audience for these devices slightly, but the RPi has a much bigger community than we have here, so I'd suggest a hell of a lot of people don't actually care about that so much. Plus if this became known as a use of the RPi CM we might get more hits from the RPi forum and promotion from RPi sites.

I dunno personally. I do quite like the work that hns and daveshah and others have done to bring this project to fruition, but if we could be prearmed for the RPiCM5 and could make units available within weeks of the new CM being released to retail, it could make ED a lot of money, I tend to think.

Edit: Here's a photo of a dummy board. It looks to me to be about three times as wide as it is tall, and about half of the main PCB's height. That resolved out at 132x43mm, so the Pi4CM is taller by about 17mm, so would likely need to run over the top of the SD card cages, but there seems to be no likelihood of the CM board being any wider than the current CPU board.

Edit2: Or maybe spin the CM by 90 degrees if it's really taller than it is wide.
 
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ToastBucket

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In terms of grunt, it's based around quad 1.5GHz 'little' 64-bit processors, so less efficient than the A15 cores in the Pyra although with four of them it might be worth playing with.
4xA72s is a huge upgrade in terms of raw power from the A15s but yes they are more power hungry than other cores. It could be comparable to A15s though, they are very inefficient cores. A72s are actually part of the big cluster in a big.LITTLE combo, there’s just no LITTLE on the BCM2711.

I know it’s fun to toy with the idea, but this will never be used in the Pyra :) Required documentation is locked down through business contracts between Broadcom and the Pi Foundation. Most importantly, boot procedure is obfuscated, which is particularly problematic for us because we need to perform very specific operations early in the boot process in order to manage some of the power management design.

if we could get our hands on some RK3399’s we may be able to leverage some of the work being done on the pine book pro as well as contribute back to their project. We could potentially have the option of running Manjaro on the Pyra too, in that case which would be sweet.
 

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if we could get our hands on some RK3399’s we may be able to leverage some of the work being done on the pine book pro as well as contribute back to their project. We could potentially have the option of running Manjaro on the Pyra too, in that case which would be sweet.
It has been suggested as a feasible candidate before :)
Manjaro on my pinebook pro is pretty decent. Though not perfect yet, I can already do a lot of "big computer things" on it.
I think it would be ideal if we could merge the efforts from both communities somewhat.
 
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RZR

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4xA72s is a huge upgrade in terms of raw power from the A15s but yes they are more power hungry than other cores. It could be comparable to A15s though, they are very inefficient cores. A72s are actually part of the big cluster in a big.LITTLE combo, there’s just no LITTLE on the BCM2711.

I know it’s fun to toy with the idea, but this will never be used in the Pyra :) Required documentation is locked down through business contracts between Broadcom and the Pi Foundation. Most importantly, boot procedure is obfuscated, which is particularly problematic for us because we need to perform very specific operations early in the boot process in order to manage some of the power management design.

if we could get our hands on some RK3399’s we may be able to leverage some of the work being done on the pine book pro as well as contribute back to their project. We could potentially have the option of running Manjaro on the Pyra too, in that case which would be sweet.
What is the problem on getting the RK3399?? Package quantity for that chip is 600 uds, so I suppose it enters whiting Pyra's production numbers.

And another question, these SOC, cannot be ordered without the IHS?? If the Pyra already has a heat spreader then there's no need for the integrated one, and it saves 1mm or so of thickness...
 

EvilDragon

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The RK3399 seems to be WAY too big. We had space issues with the OMAP5 (we originally planned to use the way smaller OMAP5430, but that one never went into production).
So fitting the 23x23mm with 1mm thickness into the little space we have seems impossible.

The best candidate right now seems to be the i.MX8M Nano.
 

EvilDragon

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Pyra's wifi/bt/cellular will likely need blobs. The sgx is a blob too
Yes, but you don't need that to boot. You can use the system without them, you would just be missing these features.
Wifi / BT could be done with a USB stick, for example, and not everyone needs the SGX.

The "to boot" is pretty horrible, in my opinion.
 

Phlyra

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The RK3399 seems to be WAY too big. We had space issues with the OMAP5

So fitting the 23x23mm with 1mm thickness into the little space we have seems impossible.

The best candidate right now seems to be the i.MX8M Nano.
So we’d be looking for something smaller than the current smallest module (35 x 40mm)?
http://linuxgizmos.com/linux-driven-i-mx8m-nano-module-is-smallest-yet/
Feel free to shoot me down/ignore me since I know you have more important things to deal with atm and I really know nothing about this, just flailing around in hope lol.
 

Alec

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What about RK3328? It's 14X14 by 0.65mm (same area but 0.15mm taller than the i.MX8M Nano), and similar specs.

I was really impressed with Rock64 because it's the first board I had where I built the latest mainline kernel and everything just worked. RockChip contributes directly upstream.

It also has Mali-450 GPU which now has open-source 3d drivers in the kernel (never tried them though, I use it as a server).
 

ToastBucket

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The RK3399 seems to be WAY too big. We had space issues with the OMAP5 (we originally planned to use the way smaller OMAP5430, but that one never went into production).
So fitting the 23x23mm with 1mm thickness into the little space we have seems impossible.

The best candidate right now seems to be the i.MX8M Nano.
Thats a bit of a bummer. With the iMX8M nano our battery life will likely go through the roof, but we'll likely be sacrificing a good amount of raw power limiting tasks like web browsing. Its hard to do a full comparison because there's a lot of differences between these core families, but a big one is the A53's are missing out-of-order execution which we see on the A15's. The Nano is also missing the VPU (so we lose multimedia decode/encode) and HDMI. Is there a reason the 8M is not an option in place of the 8M nano? I haven't looked at the physical size difference. I remember looking at the 8M and it was similar in size to the OMAP5.

All in all, it would be nice to get something with at least one A7x core for larger load tasks. Also a Mali GPU would be great as we are starting to get in-tree kernel support for Mali GPUs.

What are the restrictions on size? The RK3399 datasheet says the chip is 21mmx21mmx1.51mm. So may be a bit tall, but its smaller than 23mmx23mm.


How about RK3288 with quad core cortex A17 with Mali T-764 GPU in 19x19, 0.65mm.
I'm a bit hesitant to go with an A17. It's already just as obsolete than the A15. And to be honest, this is the only SOC I've actually seen sporting one, so I'm not very hopeful for good support for the A17 in the kernel.
 

RZR

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The OMAP 5432 is indeed a tight fit:


OMAP 5430 -> 14mmx14mmx0.4mm
OMAP 5432 -> 17mmx17mmx0.5mm

And this goes against the MOBO+heat spreader, so there must not be a lot of room regarding pitch.
 
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