miauto
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Re: ARM9 as a complement of ARM11 RPi system

Tue Aug 23, 2011 9:44 am

Hi,

i was wondering if wouldn't be awesome releasing a ARM9 RPi embedded system apart from the ARM11. ARM9 is a very powerful processor that can run Linux or Android perfectly, and i am sure you could achieve a 15$ pcb with a form factor of a usb memory.

I am sure would be an awesome idea for people that doesn't need an ARM11 power processor (applications that are not power oriented), but needs something with a smaller form factor than a credit card size, and cheaper price of course.

regards!

jamesh
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Re: ARM9 as a complement of ARM11 RPi system

Tue Aug 23, 2011 10:19 am

Quote from miauto on August 23, 2011, 10:44
Hi,

i was wondering if wouldn't be awesome releasing a ARM9 RPi embedded system apart from the ARM11. ARM9 is a very powerful processor that can run Linux or Android perfectly, and i am sure you could achieve a 15$ pcb with a form factor of a usb memory.

I am sure would be an awesome idea for people that doesn't need an ARM11 power processor (applications that are not power oriented), but needs something with a smaller form factor than a credit card size, and cheaper price of course.

regards!

We would need to find a SoC that uses the Arm 9 and still has the multimedia capabilities of the current chip, and as far as I know they are not available. Arm9 is pretty old now, and there is little or no cost difference in silicon to go to 11 over 9, so there would be little cost benefit. You could go for a simple Arm9 core with no GPU which would be cheap (if you can find one), but very slow in comparison to the current design. Arm9 also uses the Armv5 instruction set, which is becoming less well supported (if at all?) by Linux distro's

Check out http://en.wikipedia.org/wiki/A.....chitecture for more Arm details.

Going to the smaller form factor, the cost is pushed towards other components, not really the CPU - smaller pitch parts are much more expensive, and would be required at this sort of size.
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Lob0426
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Re: ARM9 as a complement of ARM11 RPi system

Tue Aug 23, 2011 12:11 pm

A smaller lower powered core could be useful for secondary tasking if you were integrating several devices into a finished product. But having a different instruction set would be a liability.

I ran across a block diagram for the Tegra 2 chipset. It had two A9 cortex cores and an ARM 11 (I believe) core also. It stated that the ARM 11 core was used for low power computing needs and bypassed the cortex processors when they were not needed. This was done to save battery power when using powerful processor cores that are also power hungry. The GPU was available to all three cores I believe.
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jamesh
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Re: ARM9 as a complement of ARM11 RPi system

Tue Aug 23, 2011 8:00 pm

Quote from Lob0426 on August 23, 2011, 13:11
A smaller lower powered core could be useful for secondary tasking if you were integrating several devices into a finished product. But having a different instruction set would be a liability.

I ran across a block diagram for the Tegra 2 chipset. It had two A9 cortex cores and an ARM 11 (I believe) core also. It stated that the ARM 11 core was used for low power computing needs and bypassed the cortex processors when they were not needed. This was done to save battery power when using powerful processor cores that are also power hungry. The GPU was available to all three cores I believe.

A9's sounds about right for the Tegra 2, not sure about the Arm11 though. Certainly feasible. I've heard though that they do run very hot and the power management is a bit iffy i.e. they cannot full at full clock speed for long without getting too hot and running the battery flat. Quite powerful though.
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Lob0426
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Re: ARM9 as a complement of ARM11 RPi system

Tue Aug 23, 2011 10:20 pm

Here is a block diagram of the Tegra 2.
http://www.anandtech.com/show/2911
I stand corrected it is an ARM7 processor.
It does not surprise me that Tegra 2 runs hot. It is a PoP package also so no real way to dissipate heat. At least not inside a phone or tablet. It probably is not the CPU cores that cause the heat. The GPU is probably the culprit there. Having a dual core that drops back to a less powerful single core for everyday tasks is smart. This saves power and heat. Most devices are not used at full power most of the time.

The x86 style multi core processors, above triple core do not really make sense anyway. I very rarely see more than two cores used even during game play. The only real way I have seen a third core work is when I used program affinity settings to force it to the third core. You can not save these affinity settings in non server windows anyway. Also many people do not realize that when an Intel processor goes into turbo mode it shuts off the last core to gain enough headroom in the TDP for it to work. With 8 and 10 core processors on the horizon this is really getting ridiculous. Intel actually stated they were going to reduce the number of cores in their processor a while back. This would have allowed them to turbo the primary and the secondary cores. It would also have gave them more thermal room for more powerful GPU's. When AMD came out with quad and six cores that must have went out the window.

The Tegra 2 using dual A9 cores for performance when needed and Scaling down to a single core when performance is not needed, makes sense. Maybe Intel and AMD need to think things over a bit!
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