The Raspberry Pi 3 Model B Q&A thread


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by jdb » Mon Feb 29, 2016 7:31 am
You should all know the drill by now:

Read the blog post announcement here:
https://www.raspberrypi.org/blog/raspbe ... 3-on-sale/

Blog comments are likely to have a few of the answers you seek already:
https://www.raspberrypi.org/blog/raspbe ... /#comments

Post otherwise in this thread.

FAQ collated from posts in this thread and around the forum:

Do I really need the uprated 2.5A PSU?
The latest revision of the official power supply (5.1V/2.5A) is recommended for use with Pi 3. As the CPUs are a lot more powerful than previous Pi iterations, they can draw substantial peak currents that may overtax other power supplies. It is unlikely that you will experience issues with the previous official PSU (2A) unless you have additional high-current devices plugged into the USB ports.

What is the available USB port power?
The USB overcurrent switch now has a fixed, unalterable limit of 1.2A.

Why doesn't my Pi 3 ever go faster than 600MHz?
Undervoltage events force a reduction to idle clockspeeds for a substantial time-out period. If you rarely see 1.2GHz while running CPU-intensive applications, check to see if you're getting the small rainbow square in the top-right of the display, or if the PWR LED (red) is blinking.

Why is there an orange/yellow square in the top right of the display?
This indicates that the Pi 3 is throttling CPU speed due to thermal limitations. There is a graceful reduction in ARM clockspeeds if the SoC exceeds 80°C and during this time a yellow square icon is rendered on-screen. Idle clockspeeds (600MHz) are forced if the SoC hits 85°C. If this is an issue for your application, buy a heatsink - even a small one will likely prevent throttling.

My Pi 3 boots but there's no wlan0 device, why?
Use the latest release of Raspbian or an updated OS image for your distribution. You can boot recent Pi 2-compatible releases on a Pi 3, but without Pi 3-specific devicetree information the WiFi/BT chipset won't be recognised by the kernel.

My GPIO-connected UART device is broken on Pi 3, why?
The mini-uart is now routed to GPIO14/15 as the PL011 UART is now used for bluetooth communications. The mini-uart doesn't have a separate clock divisor and uses the core clock frequency. Changes in core clock (e.g. through throttling or idle/load frequency changes) will result in arbitrary modification of the effective baud rate. There's no easy way around this, but as a workaround there is a pi3-disable-bt devicetree overlay in latest rpi-update firmware which reverts this change.

I bought an ARMv8 computer, I want to run ARMv8 code RIGHT NOW!
The Cortex-A53 can run ARMv7 code just fine (in fact, substantially better than Pi 2 due to architectural improvements) and this is where we are staying in terms of supported userspace and kernel for the time being. If you want to roll your own OS/kernel, you can add arm_control=0x200 to /boot/config.txt to boot the cores in ARMv8 state.

BCM43438 supports FM reception, can I hack my Pi to attach an antenna?
No. The FMRX ball on BCM43438 is underneath the chip and surrounded by more important ones that needed to be routed out. PCB technology limits (no micro-vias, no via-in-pad) meant that we couldn't route this pin out at all.

What's the peripheral bus base address on Pi 3?
Same as on Pi 2.
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by gregeric » Mon Feb 29, 2016 7:33 am
SDIO for WiFi I assume, GPIO's 34-39 alt3? Is it a 150Mbps part? iperf results?
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by jdb » Mon Feb 29, 2016 7:36 am
gregeric wrote:SDIO for WiFi I assume, GPIO's 34-39 alt3? Is it a 150Mbps part? iperf results?


Correct, bcm43438 is connected by SDIO for WiFi and UART for bluetooth. We don't do fat channels - 20MHz = 72mbit/s.
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by gregeric » Mon Feb 29, 2016 7:42 am
I guess it performs a little better than the ~42Mbps max I'm getting with an esp8266 over SDIO?
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by RaTTuS » Mon Feb 29, 2016 7:42 am
Congrats on the proper first birthday

ooh 300k Pi3 for sale on first day - I wonder how long they will last
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by Pithagoros » Mon Feb 29, 2016 7:44 am
Apart from clocking up to 1.2GHz and the other architectural improvements, is there a 64 bit Raspbian build in the pipeline, or other plans to take advantage of bigger words?
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by fruitoftheloom » Mon Feb 29, 2016 7:52 am
Pithagoros wrote:Apart from clocking up to 1.2GHz and the other architectural improvements, is there a 64 bit Raspbian build in the pipeline, or other plans to take advantage of bigger words?


over the next few months we will investigate whether there is value in moving to 64-bit mode.

The Blog is a good read :D
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by Pithagoros » Mon Feb 29, 2016 7:53 am
Pithagoros wrote:Apart from clocking up to 1.2GHz and the other architectural improvements, is there a 64 bit Raspbian build in the pipeline, or other plans to take advantage of bigger words?


Ahh OK, official blog says "will investigate" I missed that after I read the 50-60% bit.

"At launch, we are using the same 32-bit Raspbian userland that we use on other Raspberry Pi devices; over the next few months we will investigate whether there is value in moving to 64-bit mode."

But really, if you are going to call it a 64 bit SBC then........
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by RaTTuS » Mon Feb 29, 2016 7:54 am
Pithagoros wrote:Apart from clocking up to 1.2GHz and the other architectural improvements, is there a 64 bit Raspbian build in the pipeline, or other plans to take advantage of bigger words?

to quote
At launch, we are using the same 32-bit Raspbian userland that we use on other Raspberry Pi devices; over the next few months we will investigate whether there is value in moving to 64-bit mode.
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by shuckle » Mon Feb 29, 2016 7:55 am
Is there any changes to USB and wired ethernet?
Still USB2?
Still Ethernet using USB?
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by fruitoftheloom » Mon Feb 29, 2016 7:59 am
shuckle wrote:Is there any changes to USB and wired ethernet?
Still USB2?
Still Ethernet using USB?

That is covered in the BLOG ;)

All of the connectors are in the same place and have the same functionality
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by Paul Webster » Mon Feb 29, 2016 8:02 am
jdb wrote: bcm43438 is connected by SDIO for WiFi and UART for bluetooth. We don't do fat channels - 20MHz = 72mbit/s.

Looks like BCM43438 also has FM radio capability. Is there a chance of accessing it? If yes, is there a way to connect an external antenna?
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by bennettp123 » Mon Feb 29, 2016 8:04 am
https://www.raspberrypi.org/blog/raspberry-pi-3-on-sale wrote:has been replaced by a custom-hardened 1.2GHz 64-bit quad-core ARM Cortex-A53


What does “custom-hardened” mean in this context?
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by Paul Webster » Mon Feb 29, 2016 8:05 am
gregeric wrote:I guess it performs a little better than the ~42Mbps max I'm getting with an esp8266 over SDIO?

I saw a benchmark showing it as a bit under 40Mbps - see Pimoroni blog post http://blog.pimoroni.com/raspberry-pi-3/
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by fruitoftheloom » Mon Feb 29, 2016 8:08 am
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by jdb » Mon Feb 29, 2016 8:08 am
Paul Webster wrote:Looks like BCM43438 also has FM radio capability. Is there a chance of accessing it? If yes, is there a way to connect an external antenna?


Nope and nope. PCB technology limits mean that we couldn't route out the FM antenna pin. It's left disconnected underneath the chip, unfortunately.
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by ric96 » Mon Feb 29, 2016 8:10 am
Happy birthday and Congratulations!!! :D

Just a suggestion though:
I do realise that it takes a lot of work to maintain an separate repository and the idea of having a separate armv7 repo was dropped for the same reason. But I think that it just might be worthwhile to have a separate 64bit repo due to the huge performance bump. But of course only if its financially viable.
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by Pithagoros » Mon Feb 29, 2016 8:11 am
RaTTuS wrote:
Pithagoros wrote:Apart from clocking up to 1.2GHz and the other architectural improvements, is there a 64 bit Raspbian build in the pipeline, or other plans to take advantage of bigger words?

to quote
At launch, we are using the same 32-bit Raspbian userland that we use on other Raspberry Pi devices; over the next few months we will investigate whether there is value in moving to 64-bit mode.


Much more information about this from Eben in this podcast:
http://thepipodcast.com/the-pi-podcast-16-raspberry-pi-3-special-with-eben-upton/
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by lumsdot » Mon Feb 29, 2016 8:22 am
Will the pi3 be powerful enough to run a webrowser which can cope with heavy java/ javascript pages.
If it can do that , you will sell loads.
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by 0xFF » Mon Feb 29, 2016 8:27 am
Is it possible to hack with soldering iron to use external Wifi antena?
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by rpdom » Mon Feb 29, 2016 8:28 am
ric96 wrote:I think that it just might be worthwhile to have a separate 64bit repo due to the huge performance bump.

For the most part you could probably use the Debian arm64 repos for all the apps instead of the Raspbian ones, then the RPF could add their own arm64 for the Pi specific stuff that is held on the raspberrypi.org servers. The main work would be building 64 bit image files. NOOBS could stay as it is, but perhaps detect that it is running on a 64 bit system and give the option of downloading 64 bit versions of the available OSen.
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by jdb » Mon Feb 29, 2016 8:29 am
0xFF wrote:Is it possible to hack with soldering iron to use external Wifi antena?


Yes. There is an option component and a footprint for a u.FL connector on the underside of the board.
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by cjan » Mon Feb 29, 2016 8:34 am
1g of ram, 64bit cpu, what is point? more ram eating?
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by hippy » Mon Feb 29, 2016 8:36 am
I'm going to be the first to ask to get it out of the way ...

Will the full schematics of the Pi 3B be released ?
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by ric96 » Mon Feb 29, 2016 8:38 am
jdb wrote:
0xFF wrote:Is it possible to hack with soldering iron to use external Wifi antena?


Yes. There is an option component and a footprint for a u.FL connector on the underside of the board.

Is it the bit under the hdmi port? Guessing from the fcc images.
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