[offtopic]Some cheap and tiny ARM devices.

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D.J.Peters
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[offtopic]Some cheap and tiny ARM devices.

Postby D.J.Peters » Nov 28, 2015 18:53

I ordered a new toy Raspberry PI Zero to day.
Image
65 x 30 x 5 mm only 160 mAh with HDMI Full HD display enabled 512 MB max 1 GHz GPU core included.

youtube: https://www.youtube.com/watch?v=NFFQmdUc5Vg

Perfect for FreeBASIC :-)

Joshy
Last edited by D.J.Peters on Jan 23, 2016 22:08, edited 2 times in total.
sean_vn
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Re: 5$ Raspberry PI Zero

Postby sean_vn » Nov 29, 2015 4:57

I knew Mr Peters would note that first. So for $500 dollars you get 100 cores and 50 Gbytes. For $50,000 you get 10,000 cores and 5 Tbytes + a big electricity bill. On the other hand Samsung have started selling 128GB DDR4 DIMMs if you want to get extreme with memory.
With the raspberry pi's I'm sure inter-board communication would end being rather slow, but the sum memory bandwidth would be massive, the actual amount of data per second you could shift between the memory and the cores would be really extreme.
On the other hand a server board with 128Gb DIMM's would be more energy efficient for mass fast memory.
http://www.theregister.co.uk/2015/11/26/time_for_a_new_ram_cram_plan_as_128gb_ddr4_dimms_land/
Last edited by sean_vn on Nov 29, 2015 5:32, edited 1 time in total.
sean_vn
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Re: 5$ Raspberry PI Zero

Postby sean_vn » Nov 29, 2015 5:29

Well at 160 mA the power bill wouldn't be too bad and your house would be nice and warm in winter.
With 10,000 you could read through 5 Tbytes in about .5 of a second.
With 5 Tbytes on a server board it would take 10's of seconds to read through all that memory.
D.J.Peters
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Re: 5$ Raspberry PI Zero

Postby D.J.Peters » Nov 29, 2015 5:55

With the WiFi Transceiver ESP8266 it's perfect for small outdoor projects it use the RAM chip as CPU cooler. ;-)
(CPU is mounted under the RAM)

Joshy
marcov
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Re: 5$ Raspberry PI Zero

Postby marcov » Nov 29, 2015 10:48

sean_vn wrote:Well at 160 mA the power bill wouldn't be too bad and your house would be nice and warm in winter.
With 10,000 you could read through 5 Tbytes in about .5 of a second.


If I calculate that, I find myself at 5/s. 5TB/10000=100MB. 500MB is larger than the 8kb cache, so the effective speed of about .1 GB/s=100MB/s(*) applies. Could be a factor 2 better though since it was a move not read benchmark.

Note that I pick RPI1 not RPI2 values because afaik the Zero is a RPI1 CPU (says armv6 in description)

With 5 Tbytes on a server board it would take 10's of seconds to read through all that memory.


A recent PC can search through memory at about 5GB/s I guess. Can maybe get up into the low tens for search only. But that is a 100W part. (system, not CPU). Your pi does .16*5V=.8W. so you can have about 100 PIs for such system.

So it about evens out. (though the PIs also have to factor in PSU overhead, that is already factored in the PC). My guess that the PC would be better even, since the 100W is a peak, not continuous number, and definitely more compact.


(*) bottom rows of http://www.roylongbottom.org.uk/Raspber ... tm#anchor9
D.J.Peters
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Re: 5$ Raspberry PI Zero

Postby D.J.Peters » Nov 29, 2015 12:36

@marcov thank you for sharing the benchmark results.

One question I can't believe the slow OpenGL ES results.

How many shared RAM are setup for OpenGL ES benchmark or is it a fixed size on the PI hardware design ?

Joshy
sean_vn
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Re: 5$ Raspberry PI Zero

Postby sean_vn » Nov 29, 2015 14:21

Yeh, I was just guesstimating.
It really just depends on the bus speed of the memory (in decade of magnitude terms):
When I look at wikipedia https://en.wikipedia.org/wiki/DIMM I don't see that much difference between the high end ddr2 and ddr4. Well it's not decades of magnitude difference. I don't own a rpi or a high end PC so I can't just go and run the very simple tests I would need to run to actually see.
I looked at the test result page indicated. I'm not too sure about the setup there or how to interpret the results . 100 Mbytes per second would be really slow. But then I see neon SIMD loads at 700 Mbytes per second.
Maybe Intel always win.
If it was .5 of a second (or 1 second) for 5 Tbytes versus 1000 seconds on a server board then for certain specialized applications you could build a kind of mini-mega system. I'll take your word for it that it isn't that way.
Last edited by sean_vn on Nov 29, 2015 14:53, edited 1 time in total.
sean_vn
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Re: 5$ Raspberry PI Zero

Postby sean_vn » Nov 29, 2015 14:49

Note to self: Intel always win.
sean_vn
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Re: 5$ Raspberry PI Zero

Postby sean_vn » Nov 29, 2015 15:09

One thing I did think of in relation the rpi is that if you want moderately fast access to massive amounts memory. Such as say 10 of those Samsung 128 Gbyte DIMMs then the easy part is a wiring exercise between the rpi board and the DIMM's, maybe you would have to create a simple latch circuit or whatever. The hard part would be reading the datasheet and understanding all the internal registers etc that actually exist on a modern memory chip. I guess you would be down to 50 million transactions per second. You could still do things you simply couldn't do with a hard drive with 10ms latency.
If it is 100Mbytes per second with rpi , remind me not to buy one. One hour later the web page will have rendered.
Dr_D
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Re: 5$ Raspberry PI Zero

Postby Dr_D » Nov 29, 2015 21:53

Drago
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Re: 5$ Raspberry PI Zero

Postby Drago » Nov 29, 2015 22:28

Dear Joshy,

yes this Pi could be really great. I orderd 3 pi zero at reichelt. Looking forward to get them in December.

As I am always looking to extend my TimeTracking program for out RunningEvent I thought this little Pi with some Transceiver (maybe the one you mentioned) would fine to track some Split Times.

Did you do some test with this Transciever? I think I'll need to reach a distance up to 2 or 3 km.

Beside that i am still looking for some affordable RFID Reciever (UHF) including AntennaGates to Track the Finisher at the finish line.
I know there are a lot of RFID Reciever, but the finish line is about 2 or 3 meters wide.... this wil make the Antennas expensive I think.
Have anyone seen such (affordable) devices that I can connect to my PI2?

Greetings
Rainer
D.J.Peters
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Re: 5$ Raspberry PI Zero

Postby D.J.Peters » Nov 30, 2015 0:12

@Drago esp8266 Raspberry PI getting started and connect esp8266 to raspberry pi

I self tested the WiFi chip with an ordinary 8-bit MC in my garden of course not 4x4 Km :-)

Some people have test it successful with distances of 3,800 - 4,300 m.

I have 3 version of the ESP8266 two has the antenna as tracks on the board
and one with WiFi antenna connector.

If space isn't a problem for your project get a chip with external antenna.

You can get a ESP8266 bundle with antenna 7-8 € on eBay.

Joshy
sean_vn
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Re: 5$ Raspberry PI Zero

Postby sean_vn » Nov 30, 2015 4:16

The 100 Mbytes per second for DRAM read is really fishy. That's 25 million 32 bit integers per second. I think a 68000 CPU from 25 years ago could nearly equal that. Well, I can't say. Maybe they wired it up to an 8 bit DRAM chip, an 8-bit channel.
marcov
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Re: 5$ Raspberry PI Zero

Postby marcov » Nov 30, 2015 11:09

sean_vn wrote:Yeh, I was just guesstimating.
. 100 Mbytes per second would be really slow. But then I see neon SIMD loads at 700 Mbytes per second.


Afaik RPI1 (and thus Zero) has no Neon. And RPI2 has a different power envelope.

Maybe Intel always win.
If it was .5 of a second (or 1 second) for 5 Tbytes versus 1000 seconds on a server board then for certain specialized applications you could build a kind of mini-mega system. I'll take your word for it that it isn't that way.


I don't think that heaps of RPI will ever beat something. Maybe similar hardware on boards integrated deeply together and sharing one PSU, but never 1000 RPIs with 1000 different usb power adapters.

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