Official display and RPi "B"

[il_diavolo]

Screen delivered yesterday. I reformatted an SD card, downloaded NOOBS, installed rasbian and updated and upgraded.
It works perfectly with my RPi "2" but when I connect the screen to my "B" rev 2 and boot from the same SD card the display does not work.
My questions are - is the display compatible with the "B"? If it is, do I have to do anything different to get it to work?

[il_diavolo]

Has anybody got the display to work on a RPi "B"?
If so, I would be grateful if you could confirm that does.
Thanks.

[dgordon42]

The new Official Display is not compatible with the old Pi model A and B's power supply, that is to say it cannot be powered from their GPIO pins. To do so will, I believe, cause the Pi to crash, as it's power supply cannot handle the current changes the Display will cause.

To use the Display with an old Model B, use a separate 5V, 500mA power supply.

Sorry I don't have one to try out, wish I did!

Hope this helps,

Dave.

[fruit-uk]

I almost tried today but the assembly/mounting holes are in the wrong place so I ended up using a Pi2 :\

[il_diavolo]

I'm pretty sure it's not a power supply issue. I have tried all the power options offered, each with the same (non) result. The power goes into the adapter and out to the Pi successfully, either through the USB or to the GPIO pins. I have mostly been trying to get it to work using two separate 2 amp power supplies.

As an aside, I can confirm that the display still works correctly (on my Pi 2, obviously) using a 2 metre long ribbon cable rather than the short one supplied with the display. As the camera will also work with this length of cable you could probably have the display and the camera 4 metres apart!

Colin

[dgordon42]

I've been reading Gordon Hollingworth's blog announcing the new Official Display.

In answer to the question

I was just wondering, can I use the raspberry pi b (no b+ or 2b)?

Gordon answers

Unfortunately the B didn’t have the right I2C connections down the DSI connector. That’s one of the reasons for the extra pins on the display conversion board.

Will investigate what changes (software and jumper wires) would be required, but I would suggest a B+ / 2B / A+ would be the easiest addition

Looking at the schematics for the Model B, there is no I2C bus connections on the display port, but they are present on the Compute Module schematics. Don't have schematics for the B+ or the 2B.

This is a little disappointing for me, as I have plans to use the new Display with a model B. Perhaps Gordon will come up with a solution in the future.

Dave.

[il_diavolo]

Thanks. Gordon's blog may well be the explanation. I was hoping to use the Pi B with my astro telescope, the software is written in Python and Picamera. It does run headless but the latency of the image makes it very difficult to focus. The official display will (should) show the camera "preview" with little noticeable latency, Up to now I have been lugging my 15" monitor out into the back yard on a starry night! My Pi 2 is deeply embedded into my robot.
I am tempted just to connect the 3 spare adapter pins to the GPIO pins but I'm not sure what the "int" pin is. SDL and SCL seem straight forward connections to pins 3 and 5.
I'd rather someone who knows what they're doing tries it before I do, any volunteers!

Colin

[dgordon42]

Unfortunately, it's not as simple as connecting GPIO pins 2 & 3 to the I2C pins on the Display, as GPIO pins 2 & 3 on a Revision 2 Model B are I2C Bus 1, and both the Display, and the PiCamera operate on I2C Bus 0.

There seems to be no easy way of getting at I2C Bus 0 without soldering jumper leads onto the I2C pins of the Camera connector,
or the I2C Bus 0 pull-up resistors R42 & R43 on the underside of the Pi.

I plan on getting a Display around the end of the month, I may try the jumper lead solution then.

Dave.

[il_diavolo]

Thanks Dave, I'll keep watching this space.

The wording on the Swag Store site is "The display will technically work with the Model A and Model B boards (connecting it to the DSI port on the Pi board), however the mounting holes on the back of the display will only line up with the newer board design (A+, B+ and Pi2)" which I interpreted as just a simple mounting mod required.It certainly stretches the meaning of "compatibility" beyond what I would consider reasonable. I suggest that the wording is amended on that site (and other retailers) before someone less forgiving than me gets Trading Standards involved!

Colin

[ait]

Hello Dave,

There seems to be no easy way of getting at I2C Bus 0 without soldering jumper leads onto the I2C pins of the Camera connector,
or the I2C Bus 0 pull-up resistors R42 & R43 on the underside of the Pi.

I solderd 2 wires from the display-connector to R42/43 - it works fine.
It is a RPI B Rev 2.
Maybe a kind of adapter cable (splittet DSI Ribbon cable) would work.
So one part of the adapter cable in the display-connector, the other part in the camara-connector.

Tomorrow i will try solder wires to RPI B Ver. 1


Ait

[ait]

Hello Colin,
on the cardboard box of the display is written:

Code: Select all

 Compatible with all Raspberry Pi models (N.B. the mounting holes are not compatible with the original Model B, Model A bords)

Ait

[helsthomas]

I'd be very interested to see if anyone can get this to work with a model B - I bought the screen on the basis that it was technically compatible (mounting holes aside). I've updated Raspian and tried all the power options, and nothing. Thanks all!

[rpdom]

As I understand it there are a few software changes that need to be done to get the screen working with the earlier Pi models, and it will be necessary to use the jumper cables to connect to the I2C pins.

Just give them some time

[ait]

I solderd 2 wires from the display-connector to R42/43 - it works fine.
It is a RPI B Rev 2.

Tomorrow i will try solder wires to RPI B Ver. 1

Tryed it.
RPI B Ver. 1 didn't work in that way.

Ait

[dgordon42]

@Ait, Thanks for jumping the I2c Bus 0 signals from R42/43 on the Rev 2 Model B, and getting the Display to work

The Rev 1 Model B is a little different, as R42/43, and the Camera port is connected to I2c Bus 1!
Two possible solutions come to mind, and may be worth trying:
1. With R42/43 connected onto the Display I2c pins, try enabling the camera in raspi-config. This might get the GPU to use I2c Bus 1, and talk to the Display, or,
2. Just try connecting GPIO pins 3 (SDA) and pin 5 (SCL) from the Pi to the Display. On a Rev 1, this is I2c Bus 0.

I have noticed that Gordon Hollingworth's Display Blog talks about hardware and software mods to get the Display to work with a Model B, as @rpdom pointed out above.
As I understand it, either or both I2c Buses can be controlled by the VideoCore GPU, or the ARM CPU. This is set in the device-tree software. Much of the code controlling both the Display and the Camera seem to run in the GPU, therefor the I2c Bus used to talk to these devices is controlled by the GPU. Due to the difficulty of getting at the 'normal' GPU I2c Bus (soldering onto R42/43, etc.), my fear is that the Foundation's solution will be to control both I2c Buses with the GPU. This would make it easy to connect the Display (jump GPIO pins to the Display), but would mean no I2c for the user. I need an I2c Bus to talk to my Arduino and a Real Time Clock. The Original Poster ( il_diavolo), wishes to use both the PiCamera and the Display on a Rev 2 Model B.

I look forward to seeing the Foundation's solution to getting the Display to work with Revisions 1 & 2 of the old Models A & B.

Thanks to @Ait's conformation that the Display will work by connecting R42/43 to the display, I know now that I can make the Display work with my Model B Rev 2, even if I have to use some of the Model B+ device-tree overlay.

Dave.

[il_diavolo]

Good work ait.
Would you be able to post a photo of your hack on the Pi 2 rev 2? I'm not putting a soldering iron anywhere near my Pi unless I'm certain about what I'm doing!
(My iron is more suitable for macro electronics rather than micro.)

Colin

[ait]

Hi Colin,
the pictures of the RPI B Rev 2
(there is no Debian 14.4.12 (german date) on the sd-card (which is written on the card),
it is a Raspian 2015-05-05 with apt-get update + upgrade and rpi-update on it)







Hi Dave,

2. Just try connecting GPIO pins 3 (SDA) and pin 5 (SCL) from the Pi to the Display. On a Rev 1, this is I2c Bus 0.

i tried before, didn'nt work.

1. With R42/43 connected onto the Display I2c pins, try enabling the camera in raspi-config. This might get the GPU to use I2c Bus 1, and talk to the Display

haven't tried it. will do it soon.

Ait

[ait]

Hi Dave,

With R42/43 connected onto the Display I2c pins, try enabling the camera in raspi-config. This might get the GPU to use I2c Bus 1, and talk to the Display, or,

did not work either.

Ait

[il_diavolo]

Thanks for the pics, Ait. I'll see if I can pluck up the courage to try it!
Colin

[dgordon42]

Great pictures, thanks Ait.
I don't know why you cannot get the Display to work on the Rev. 1 board. No chance of a bad connection? Do you know if a PiCamera works on the Rev. 1 Pi?

Can't wait to see the Foundation's solution to this, and if the PiCamera and I2c Bus 1 will still work as normal. I would expect them to release it sooner rather than later, but I understand it takes time to develop and test these things.

Thanks again,
Dave.

[ait]

Hi Dave,
the camera works.

Ait

[ait]

Hello,
to solder wires to the Display-connector is one possibility to use the Display with the RPI B Rev 2,
another possibility is to made an adaptor which took the i2c bus from the camera-connector..
So i bought a RPI-Camara Kabel and splittet some wires (pin 11 +12 from the display-connector)
and put those 2 splitted wires to the camera -connector to (pin 13 +14 camera-con.).

Camara-cable


splitted



the 2 splitted wires on a plastic sheet


Display-connector


Camara-connector


Raspi with Display

[dgordon42]

That's a great idea, just modifying the flexi-cable instead of the Pi!

Can't wait to see what the Foundation come up with.

Thanks,
Dave.

[il_diavolo]

I had been thinking of trying something similar myself after seeing Ait's wiring pics. As I want to use the camera at the same time as the display I was thinking of making the modified strips with the conductor exposed on both sides. I haven't tried it to see if the two thicknesses (camera cable + display cable) would fit into the camera socket together. I suspect not.

Colin

[agh]

Hello, I'new here. I'm interesting get the offivial Touchscreen working on my Pi B Rev.2.
I read something about the I2C Bus and understand that not on the DSI Port. So I'm using the two Connectors (SCL/SDA) on the Display Card. Someone told, that the I2C Bus0 must be used. Ok, so I'm use the right Pin on J5, soldering the cable on it.

But now, it don't work.
on the config.txt I set:
dtparam=i2c_vc
dtoverlay=rpi-ft5406

I'm using Jessie Kernel 4.1.14+

Have anyone some ideas, what I can do or make better?
Thanks for your answers