ShiftPlusOne
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Re: The Raspberry Pi Model B+ Q&A thread

Mon Jul 14, 2014 12:07 pm

joan wrote:
ShiftPlusOne wrote: ...
Not sure what you mean, but I'm going to go with 'yes'. =)
I'm trying to find out what works if you supply power via the P1 header.

Yes, GPIO and CPUs.
No, USB.

Will everything else work, Ethernet, HDMI, audio, composite video, i,e, is it just the USB ports which won't work if you power via P1 rather than the microUSB?
Oh no, that's not what I meant. Everything works fine, you're just bypassing input protection, as jdb pointed out.

I was just reiterating that you can't power it by backfeeding over usb.

Sorry, I was being too terse there.

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Second I2C bus

Mon Jul 14, 2014 12:09 pm

Hi Group,

I just looked at the pin assignments of the new B+, and I could not find the second I2C bus (the one that used to be on P5). Does that mean that the B+ exposes only one I2C bus?

Cheers
Jens
Last edited by JensKrueger on Mon Jul 14, 2014 12:09 pm, edited 1 time in total.

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Re: The Raspberry Pi Model B+ Q&A thread

Mon Jul 14, 2014 12:09 pm

redhawk wrote:
One of the launch videos does show a Raspi break out board mating to the new header without issue
What's the URL for the launch video??

Richard S.
I think they're talking about mine...

http://youtu.be/iP3RxoxYMFw

Where it shows the B+ with a RasPiO Breakout on it. Fits perfectly. :)
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Re: The Raspberry Pi Model B+ Q&A thread

Mon Jul 14, 2014 12:11 pm

Thanks. It was made clear in some subsequent posts which I didn't notice.

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Re: Second I2C bus

Mon Jul 14, 2014 12:20 pm

JensKrueger wrote:Hi Group,

I just looked at the pin assignments of the new B+, and I could not find the second I2C bus (the one that used to be on P5). Does that mean that the B+ exposes only one I2C bus?

Cheers
Jens
See the beginning of this topic:
http://www.raspberrypi.org/forums/viewt ... 92#p577692

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Re: The Raspberry Pi Model B+ Q&A thread

Mon Jul 14, 2014 12:34 pm

sorry must have overlooked that, and wow, that was a quick response :-)

Thanks!

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Re: The Raspberry Pi Model B+ Q&A thread

Mon Jul 14, 2014 12:54 pm

does the change in sdcard also improve read/write speeds??
what is the use of the two gpio pins that "should not" be used??
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Re: The Raspberry Pi Model B+ Q&A thread

Mon Jul 14, 2014 12:57 pm

ric96 wrote:does the change in sdcard also improve read/write speeds??
what is the use of the two gpio pins that "should not" be used??
The choice of slot does not affect sd card speed.

The pins in question have already been discussed in this thread and the one below.
http://www.raspberrypi.org/forums/viewt ... 44&t=81733

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Re: The Raspberry Pi Model B+ Q&A thread

Mon Jul 14, 2014 1:09 pm

Excited about using this one - USB HDD compatibility and tidier port layout makes for a nice HTPC.

Curious as to whether we can expect the model A to be upgraded to an improved power supply any time soon?

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Re: Second I2C bus

Mon Jul 14, 2014 1:12 pm

PiGraham wrote:
JensKrueger wrote:Hi Group,

I just looked at the pin assignments of the new B+, and I could not find the second I2C bus (the one that used to be on P5). Does that mean that the B+ exposes only one I2C bus?

Cheers
Jens
See the beginning of this topic:
http://www.raspberrypi.org/forums/viewt ... 92#p577692
According to the pinout below, the sda0 scl0 (GPIO0 and GPIO1 aka ID_SC and ID_SD) pins are not to be used for anything other than the eeprom. That means that we lose I2C-0...officially.


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Re: The Raspberry Pi Model B+ Q&A thread

Mon Jul 14, 2014 1:13 pm

If anyone has a B+ board, there is a hidden config option:

Code: Select all

safe_mode_gpio=4
By default the USB ports are limited to 600mA.
With the new option, this is increased to 1200mA.

Note: this was just for internal testing. In the next firmware update this will be renamed to

Code: Select all

max_usb_current=1
The idea is you only set this option if you know you have a good (e.g. 2A) power supply.

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Re: Second I2C bus

Mon Jul 14, 2014 1:18 pm

Richard-TX wrote:
PiGraham wrote:
JensKrueger wrote:Hi Group,

I just looked at the pin assignments of the new B+, and I could not find the second I2C bus (the one that used to be on P5). Does that mean that the B+ exposes only one I2C bus?

Cheers
Jens
See the beginning of this topic:
http://www.raspberrypi.org/forums/viewt ... 92#p577692
According to the pinout below, the sda0 scl0 (GPIO0 and GPIO1 aka ID_SC and ID_SD) pins are not to be used for anything other than the eeprom. That means that we lose I2C-0...officially.


Image
Isn't that port available on the camera connector?
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Re: The Raspberry Pi Model B+ Q&A thread

Mon Jul 14, 2014 1:22 pm

Heater wrote:I would say the new 40 pin header is backwards compatible enough. One of the launch videos does show a Raspi break out board mating to the new header without issue. I'm sure such connectors can be used everywhere else.

I guess to be truly backward compatible as you suggest would require keeping the old header and adding a new one nearby leaving enough space for any old connectors. I very glad the expansion was not done that way. the 40 pin header solution is far more elegant.
I would have liked to have seen a pin (or 2) of the 40 removed to make a key to stop the connector being misaligned or reversed, and maybe a shrouded connector.

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Re: Second I2C bus

Mon Jul 14, 2014 1:23 pm

jamesh wrote:
Richard-TX wrote: According to the pinout below, the sda0 scl0 (GPIO0 and GPIO1 aka ID_SC and ID_SD) pins are not to be used for anything other than the eeprom. That means that we lose I2C-0...officially.


Image
Isn't that port available on the camera connector?
Fat lot of good it does being there. That is really beside the point. They officially say "DO NOT CONNECT TO THESE PINS"
Last edited by Richard-TX on Mon Jul 14, 2014 1:32 pm, edited 3 times in total.
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Re: The Raspberry Pi Model B+ Q&A thread

Mon Jul 14, 2014 1:25 pm

I like the idea of 4 USB ports (and 4 mounting holes!) but not crazy about the nearly 18% increase in price from the local supplier (element 14) :o
Maybe an exchange rate thing?

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Re: Second I2C bus

Mon Jul 14, 2014 1:31 pm

Richard-TX wrote: According to the pinout below, the sda0 scl0 (GPIO0 and GPIO1 aka ID_SC and ID_SD) pins are not to be used for anything other than the eeprom. That means that we lose I2C-0...officially.
I'm not the guy handling this but I would hope that once the spec is actually writen this requirement can be relaxed to be something more like the beaglebone where a range of addresses are reserved for ID eeproms but the rest are available for use.

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Re: Second I2C bus

Mon Jul 14, 2014 1:33 pm

plugwash wrote:
Richard-TX wrote: According to the pinout below, the sda0 scl0 (GPIO0 and GPIO1 aka ID_SC and ID_SD) pins are not to be used for anything other than the eeprom. That means that we lose I2C-0...officially.
I'm not the guy handling this but I would hope that once the spec is actually writen this requirement can be relaxed to be something more like the beaglebone where a range of addresses are reserved for ID eeproms but the rest are available for use.
There is always hope. But the way it sits now, we have lost something.
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Re: The Raspberry Pi Model B+ Q&A thread

Mon Jul 14, 2014 1:36 pm

But gained a lot more...!
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Re: The Raspberry Pi Model B+ Q&A thread

Mon Jul 14, 2014 1:39 pm

jamesh wrote:But gained a lot more...!
In my opinion what was gained is all but useless. With the addition of a few $1 chips you can (could) have 256 GPIO pins. Now that number is halved. In other words we have lost at least 128 GPIO pins. :shock: :shock:

Reserving an i2c address for an eeprom is fine. Reserving an entire bus is another matter altogether.
Last edited by Richard-TX on Mon Jul 14, 2014 1:44 pm, edited 2 times in total.
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Re: The Raspberry Pi Model B+ Q&A thread

Mon Jul 14, 2014 1:41 pm

fruitoftheloom wrote:Please can you clarify the PSU specifications ?

I have ordered a B+ and a 2A PSU, rather than use my existing 1A, to be covered..
The PSU you need depends what you are plugging into the GPIO and USB ports. Given the same perhipherals I would expect the power consumption of a B+ to be a bit lower than a B.
redhawk wrote:According to the CPC website the GPIO pins have been extended from 26 to 40 it also claims that it's backwards compatible with existing 26 pin projects.
This is actually wrong since a 26 pin connector will not be able to sit on a 40 pin GPIO due to the housing hitting pins 27 and 28.
As has already been pointed out this is not usually an issue with board to board connectors.

With ribbon cable afaict you have three choices

1: add a 40 way connector to the cable
2: use stacking headers to lift the connector above the pins.
3: use brute force and bend the pins slightly

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Re: Second I2C bus

Mon Jul 14, 2014 1:44 pm

Richard-TX wrote:
plugwash wrote:
Richard-TX wrote: According to the pinout below, the sda0 scl0 (GPIO0 and GPIO1 aka ID_SC and ID_SD) pins are not to be used for anything other than the eeprom. That means that we lose I2C-0...officially.
I'm not the guy handling this but I would hope that once the spec is actually writen this requirement can be relaxed to be something more like the beaglebone where a range of addresses are reserved for ID eeproms but the rest are available for use.
There is always hope. But the way it sits now, we have lost something.
One of the I2C buses need to be "reserved" for use by Videocore to talk to the camera (and probably Display as well). Use of I2C0 on the ARM is not recommended as e.g. if you fire up Raspicam then Videocore will assume it has exclusive control of the interface, and start talking to it.

There is no electrical reason why you cannot connect random things to I2C-0, but unintended operation (including crashes/lockups) may occur if/when both Videocore and the ARM try to talk to the same piece of hardware at the same time.
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Re: Second I2C bus

Mon Jul 14, 2014 1:53 pm

First of all, great work guys! Love the additional USB ports, I/O, proper mounting holes, better power supply.

Regarding the Videocore causing limitations for I2C-0

The ID eeproms would also cause issues if the Videocore truly used it randomly.

Logic dictates that the Videocore uses a range of I2C addresses that do not conflict with the EEPROM's addresses.

The Foundation should document what I2C addresses are off-limits due to Videocore, which would tell us what I2C addresses are safe for non-EEPROM peripherals. Much better than allowing for random conflicts - and there should be no NDA issues, as the Foundation would not have to document the *function* of the I2C addresses used by the Videocore.
jdb wrote:
Richard-TX wrote:
One of the I2C buses need to be "reserved" for use by Videocore to talk to the camera (and probably Display as well). Use of I2C0 on the ARM is not recommended as e.g. if you fire up Raspicam then Videocore will assume it has exclusive control of the interface, and start talking to it.

There is no electrical reason why you cannot connect random things to I2C-0, but unintended operation (including crashes/lockups) may occur if/when both Videocore and the ARM try to talk to the same piece of hardware at the same time.
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Cost over $50 at Newark

Mon Jul 14, 2014 1:56 pm

Cost?
Newark / Element 14 has the B+ listed for 50.59 USD. The description says $35.00 but the higher price is shown on checkout cart.
Is this just a pre-order price that will go down to $35 in the near future after the rush?
Unless specified otherwise my response is based on the latest and fully updated Raspbian Stretch w/ Desktop OS.

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Re: The Raspberry Pi Model B+ Q&A thread

Mon Jul 14, 2014 2:02 pm

Not sure if this has been mentioned. There are a couple of standard for 4 pole audio + video connectors:
http://pinoutsguide.com/PortableDevices ... nout.shtml

We matched the iPod Video scheme. The main reason for this is to work with 4-pole headphones that include a microphone:
http://en.wikipedia.org/wiki/Phone_conn ... 28audio%29

Allows headphones from: "Apple, HTC, latest Nokia, latest Samsung, latest Sony (2012+), latest Wiko (2013+), Jolla,[18] most Android phones" to work.

(Note: we don't support the microphone, but want the ground in the same place or you get awful audio).

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Re: Second I2C bus

Mon Jul 14, 2014 2:02 pm

jdb wrote:
Richard-TX wrote:
Richard-TX wrote: According to the pinout below, the sda0 scl0 (GPIO0 and GPIO1 aka ID_SC and ID_SD) pins are not to be used for anything other than the eeprom. That means that we lose I2C-0...officially.

There is always hope. But the way it sits now, we have lost something.
One of the I2C buses need to be "reserved" for use by Videocore to talk to the camera (and probably Display as well). Use of I2C0 on the ARM is not recommended as e.g. if you fire up Raspicam then Videocore will assume it has exclusive control of the interface, and start talking to it.

There is no electrical reason why you cannot connect random things to I2C-0, but unintended operation (including crashes/lockups) may occur if/when both Videocore and the ARM try to talk to the same piece of hardware at the same time.
The restriction regarding the camera and i2c-0 is well known to me. In my application a camera would be pointless so it does not matter.

In looking back at the history, I2c-0 went from the only bus available to "Thou shalt not use" in 2 revisions.
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