The Raspberry Pi 3 Model B Q&A thread

[gsh]

The problem with those measurements is that they don't measure instantaneous peak power consumption which is extremely important. When your processor kicks off to do something important it can easily triple the power consumption for a few micro seconds. You'll not notice this on a DVM...

But we do assume 1.2A continuous for the USB supplies, so if you've got nothing plugged in there then you're looking at 1.3A min instead... But considering HDDs can pull 2A from a USB connector (when the spec says a maximum of 500mA you have to wonder why PC manufacturers allow this)

[mosespi]

Thanks for the reply Gordon. Almost forgot about peak load. I tell people if they have a pile of USB supplies to try them all, line and load regulation is almost never published and overall power quality unknown. They shouldn't be surprised when a 1A supply works better then the 2A one they got from the dollar store / pound shop. That or buy the recommended one, but that is too easy.

I'll save the what should never be on USB discussion, including my LED lit coffee cup warmer, for another thread

Regards,
-Moses

[Kiefer]

Does the onboard wifi have an activity Led?

Cheers, Harry

[croston]

when someone gets hold of one could you post the revision?

Code: Select all

grep Revision /proc/cpuinfo

thanks!

Revision is a02082

[gkreidl]

Hi guys,

My question is simple i would like to know if the PI3 can play 60 fps 720p videos on YouTube ?

Thx for the answer!

This has always been possible with the right kind of software. Inside the browser (epiphany, kweb3) usually a lower resolution is used.

[alexeames]

The problem with those measurements is that they don't measure instantaneous peak power consumption which is extremely important. When your processor kicks off to do something important it can easily triple the power consumption for a few micro seconds. You'll not notice this on a DVM...

Thanks for this Gordon. I will put a comment on the blog next time I update it in a day or two. The main reason I do these measurements is so that people using battery power can calculate their required capacity.

[mosespi]

I read the BT module is on a UART. Would this be the UART that is on pin 8/10 of the GPIO or a separate UART? Hoping it doesn't use up the UART on the GPIO pins.

On a side note.. FM reception!! Now that would be neat to play with. With some luck it's just a software patch and wire antenna.

Regards,
-Moses

[karrika]

Is the UART on the 40 pin GPIO connector still at the same device address /dev/ttyAMA0?

Can the port still be run with non-standard baud rates like 250k for DMX and 31250 for MIDI? These are working on the other Raspberry Pi models.

I am still waiting for my Raspberry Pi 3 model. Hoping that the serial stuff still works.

[9pi]

The Arasan eMMC block is the only block that can do UHS and this is now connected to the onboard WiFi. The Broadcom SDHOST (which doesn't do UHS modes, but can be overclocked) now talks to the SD card.

Is there register-level documentation available for programming the SDHOST interface? I don't see it in mentioned the "BCM2835 Arm Peripherals" document. It would be useful to be able to adapt Plan 9 to run on the Pi3 without losing access to the SD card.

[gregeric]

Is the UART on the 40 pin GPIO connector still at the same device address /dev/ttyAMA0?

Can the port still be run with non-standard baud rates like 250k for DMX and 31250 for MIDI? These are working on the other Raspberry Pi models.

I am still waiting for my Raspberry Pi 3 model. Hoping that the serial stuff still works.

From what has been said, it's now the other serial peripheral, so /dev/ttyS0.

See viewtopic.php?f=63&t=137932&start=50#p915614 re baud rates.

[gregeric]

The Arasan eMMC block is the only block that can do UHS and this is now connected to the onboard WiFi. The Broadcom SDHOST (which doesn't do UHS modes, but can be overclocked) now talks to the SD card.

Is there register-level documentation available for programming the SDHOST interface? I don't see it in mentioned the "BCM2835 Arm Peripherals" document. It would be useful to be able to adapt Plan 9 to run on the Pi3 without losing access to the SD card.

There are two different linux drivers for it you can use as a reference (an old one and PhilE's shiny new one)... the RPiF engineers only got documentation for it themselves about a year ago (afaicr, mentioned on this forum).

[jamesh]

I read the BT module is on a UART. Would this be the UART that is on pin 8/10 of the GPIO or a separate UART? Hoping it doesn't use up the UART on the GPIO pins.

On a side note.. FM reception!! Now that would be neat to play with. With some luck it's just a software patch and wire antenna.

Regards,
-Moses

I don't believe the FM side of the chip is routed out, so I suspect it's not usable at all (and not modifiable to make it usable)

[PeterO]

FYI : Pi3s ordered from CPC yesterday are arriving via UPS this morning
PeterO

[mikerr]

On a side note.. FM reception!! Now that would be neat to play with. With some luck it's just a software patch and wire antenna.

I don't believe the FM side of the chip is routed out, so I suspect it's not usable at all (and not modifiable to make it usable)

The FM aerial pin apparently isn't routed out - so I guess you'd have to be sitting on a radio mast to receive any signal at all ,
making it effectively unuseable.

[RaTTuS]

FYI : Pi3s ordered from CPC yesterday are arriving via UPS this morning
PeterO

damn you
mine ordered yesterday : 7:30 pimoroni is still being prepared for dispatch
cpc one ordered yesterday @ 9:16 says it's complete but I'm still awaiting delivery

[9pi]

Is there register-level documentation available for programming the SDHOST interface? I don't see it in mentioned the "BCM2835 Arm Peripherals" document. It would be useful to be able to adapt Plan 9 to run on the Pi3 without losing access to the SD card.

There are two different linux drivers for it you can use as a reference (an old one and PhilE's shiny new one)... the RPiF engineers only got documentation for it themselves about a year ago (afaicr, mentioned on this forum).

Thanks, I'm aware that there are linux drivers. In my experience, reverse engineering driver code, and inferring a device specification from it, is much more work than writing a simple new driver from scratch from a concise spec. Separating out what is essential to the operation to the device, from the particularities of interfacing with the rest of the existing operating system context, can add a huge extra burden of complexity.

The Plan 9 driver for the Arasan MMC interface was easy to produce, thanks to the clear register-level description in the BCM2835 document. That's why I'm hoping to find a similar writeup for the SDHOST interface.

Suppose Broadcom had told the Foundation engineers "You can't have the interface documentation, but here's some example Plan 9 code which should allow you to figure it out". Somehow I don't think they would have been thrilled.

[ssvb]

Maybe raspi.tv will update their page soon. I find it pretty accurate. As found here: http://raspi.tv/2015/raspberry-pi2-powe ... easurement

One problem is that they are using a very light workload when measuring power consumption. Also the "sysbench --test=cpu --cpu-max-prime=20000 --num-threads X run" test mentioned at http://blog.pimoroni.com/raspberry-pi-3/ is very far from being the heaviest task for the CPU. If you want to check a realistic peak power consumption using real heavy applications, then NEON optimized video transcoding or running a NEON optimized litecoin miner would be among the heaviest ones.

Also a synthetic NEON optimized cpuburn implementation tuned for Cortex-A53 can be found here: https://raw.githubusercontent.com/ssvb/ ... burn-a53.S
It is somewhat more power hungry than real NEON applications, but the whole point is to stress the cooling system and the PSU to ensure that there is at least a bit of safety headroom (because there is also the GPU which might be used simultaneously with the CPU). I have been told in the #odroid irc channel that it took ~2 minutes to run it until throttling on an ODROID-C2 board, which uses quad Cortex-A53 clocked at 2GHz but has a heatsink. It would be interesting to know how the Raspberry Pi 3 can handle this cpuburn-a53 test.

[DougieLawson]

FYI : Pi3s ordered from CPC yesterday are arriving via UPS this morning
PeterO

damn you
mine ordered yesterday : 7:30 pimoroni is still being prepared for dispatch
cpc one ordered yesterday @ 9:16 says it's complete but I'm still awaiting delivery

My one ordered from RS yesterday shows that it's on a Royal Mail van for delivery right now. (Which is a whole lot better than my first RPi in 2012 which took ten weeks for RS to deliver it.)

I just wonder how fast it will run the Hercules mainframe emulator (and whether I can squeeze any extra performance by rebuilding Herc with any special compiler options). That'll be the first test after I've mounted it on my RPF touch screen.

[Pithagoros]

I have one ordered from PiHut yesterday, was delivered this morning.
Ordered 0717, shipping confirmation 1339.

Still in its box though, because of my day job.

[Massi]

in italy RS and farnell have changed their policy (with pi2 i could buy straight from RS) and they sell to retail customers only using other resellers with a "easy" 9€ dispatch cost from France
So this is definitely my destiny

[mikerr]

Is the WifF 2.4GHz only ?

[HankB]

They shouldn't be surprised when a 1A supply works better then the 2A one they got from the dollar store / pound shop.

Indeed!
I bought a cheap powered USB hub from Amazon and plugged a heavy duty load into it. Between the load and hub I included one of those cheap (~15$US) USB meters. Voltage and current wandered a bit with voltage dropping below 4.4V (minimum spec for USB 2.0.) Current draw was low too at (IIRC) about 160 mA. Rating on the power supply was 1000 mA at 5V and it fell far short.

Your point is well taken. I also find it useful to have a USB volt/current meter so I can see what is going on. For example I know that my Pi2B uses about 220 mA driving my 'fireplace video.'

As for the Pi3B, this is exciting. (And I'm so glad I managed to snap up one of those Pi2Bs on sale at Amazon on Sunday. ) Is there a mention of vendors for this device anywhere? Will it be generally available like the Pi2B or will a small handful of suppliers carry it like the Pi0? (And incidentally the Chicago/Central Microcenter shows stock for the Pi0 right now.)

Thanks!

[fruitoftheloom]

Is the WifF 2.4GHz only ?

Yes according the Official Blog

[lb]

Does the WiFi chipset support channel 13 (in regions where it is allowed)? I can't find any clear info on this.

[mikerr]

Is the Wifi 2.4GHz only ?

Yes according the Official Blog

It actually only says 802.11n - which is in the real world is not exclusively 2.4GHz and can be on 5Ghz too.

Ok, the pi is 2.4GHz only.