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by karlkiste
Sat Dec 12, 2015 10:57 am
Forum: Official Foundation Display
Topic: Longer ribbon cable
Replies: 7
Views: 4701

Re: Longer ribbon cable

So any cables saying it work for the Raspberry Pi camera should work for the screen, right? No... No other than the standard cable is tested and certified. This applies to the camera, too. People have found out that the camera occasionally works with longer cables. So might the touchscreen, too. Yo...
by karlkiste
Thu Dec 10, 2015 5:54 am
Forum: Official Foundation Display
Topic: Duel 7 in raspberry touch screen display
Replies: 11
Views: 2012

Re: Duel 7 in raspberry touch screen display

For two displays you'll need two Pis. Perhaps with some buffers/drivers the display might be copied, but that would probably need a custom PCB, at least for the FFC connectors. Combining the two touch inputs will be the hard thing. I wouldn*t even think about trying that. Using two B+ Pis, connectin...
by karlkiste
Tue Dec 08, 2015 8:52 am
Forum: Official Foundation Display
Topic: Can I run the 7" touch raspberry monitor and this case?
Replies: 7
Views: 1415

Re: Can I run the 7" touch raspberry monitor and this case?

There are cases for sale which cover the backside of the display and the attached Pi.

For my own workshop use I have nothing but a laser-cut acrylic sheet plus some bolts and standoffs.
by karlkiste
Tue Dec 08, 2015 5:41 am
Forum: Official Foundation Display
Topic: Can I run the 7" touch raspberry monitor and this case?
Replies: 7
Views: 1415

Re: Can I run the 7" touch raspberry monitor and this case?

Probably not.

There is not even an opening for the DSI data cable.

edit: The conversion board must be mounted flat to the back of the display, there's no centimeter of extra cable length to mount the conversion board in any other way.

Greets,
Kiste
by karlkiste
Mon Dec 07, 2015 11:46 am
Forum: Official Foundation Display
Topic: PI Foundation 7 inch screen power problems
Replies: 1
Views: 440

Re: PI Foundation 7 inch screen power problems

That rainbow patch does not indicate poor power to the display, but a voltage below 5V at the Pi. Probably it is just your cable connecting the Pi with display and the power supply. The resistance of that cable causes the voltage to drop a certain amount per milliamp. Even if your power supply can d...
by karlkiste
Mon Dec 07, 2015 11:37 am
Forum: Official Foundation Display
Topic: 7" touch sceeen usage & power adapter
Replies: 4
Views: 2704

Re: 7" touch sceeen usage & power adapter

By chance I do have it all connected up right here: a Pi B+ and a touchscreen with a seperate power supply on an (albeit cheap) power meter. The meter is connected on the line side of a switching power supply, so the current calculated for 5V is really lower than these numbers: Display powered, but ...
by karlkiste
Mon Dec 07, 2015 8:52 am
Forum: Official Foundation Display
Topic: Waterproof Touch Screen
Replies: 9
Views: 10839

Re: Waterproof Touch Screen

For this special case I'd recommend to look for a resistive touchscreen. It has a double plastic foil on the surface which senses applied pressure. While in many cases capacitive touchscreens are preferable, resistive ones work even when the surface is wet, and they even work when wearing thick glov...
by karlkiste
Mon Dec 07, 2015 8:27 am
Forum: Beginners
Topic: Sleep Mode - and or turn off backlight?
Replies: 202
Views: 93381

Re: Sleep Mode - and or turn off backlight?

Well, actually they have told us it is not possible. Unfortunately we can only support on/off switching of the backlight on the DSI display. Variable brightness control won't be possible. Now we would like very much to know why not? ... I have no idea ;-) But I can give some possibel causes: EMI pr...
by karlkiste
Wed Jan 07, 2015 10:26 am
Forum: Graphics, sound and multimedia
Topic: Click noise when starting analog audio sound playback
Replies: 18
Views: 18297

Re: Click noise when starting analog audio sound playback

I'm confused :? I understand from the post that a new update should solve the 'clicking' when using Alsa Unfortunately this seems not to be the case for me. I still hear ‘clicks’ between two calls to snd_pcm_writei , which are separated in time (if I call it in a for loop no ‘cliks’, but if I execu...
by karlkiste
Wed Apr 16, 2014 8:43 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Data diode (unidirectional comm) between 2 RPis
Replies: 28
Views: 11865

Re: Data diode (unidirectional comm) between 2 RPis

stevend wrote:You would need to replace the resistor with a 'shunt' voltage regulator
Thank you for backing me up here, confirming the error I have made (and corrected in a later post). It's always better to have someone else check the ideas back before hardware is to be fried :-)

Greets,
Kiste
by karlkiste
Wed Apr 16, 2014 2:57 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Data diode (unidirectional comm) between 2 RPis
Replies: 28
Views: 11865

Re: Data diode (unidirectional comm) between 2 RPis

I'm intrigued. What uses does this have. I also was confused at first. But there are use cases. Think of "data leaking out" not like an accident, but as the result of an evil hacker attack. Say, it is log files of a high-security system which a hacker wants to modify to conceal his dirty work. If t...
by karlkiste
Wed Apr 16, 2014 2:48 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Data diode (unidirectional comm) between 2 RPis
Replies: 28
Views: 11865

Re: Data diode (unidirectional comm) between 2 RPis

Yes and no... The schematics is what I had in mind, but the constant current module needs some voltage to work with. So, it must be powered with probably 7 volt or more. And, thinking again about what I wrote earlier, I'm starting to find it might be nonsense... While the resistor does limit the vol...
by karlkiste
Wed Apr 16, 2014 5:47 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Data diode (unidirectional comm) between 2 RPis
Replies: 28
Views: 11865

Re: Data diode (unidirectional comm) between 2 RPis

In the mean time I'm also trying to figure out how to prevent data leaking from the power cable. That's easy, when efficiency is not a concern: Use a constant-current power-supply. The output is connected to the private pi, in parallel with a power resistor. Say, your power supply delivers 1000mA, ...
by karlkiste
Thu Jan 30, 2014 5:35 pm
Forum: Raspbian
Topic: Kweb Suite (Minimal Kiosk Browser, omxplayerGUI)
Replies: 1529
Views: 655006

Re: Minimal Kiosk Browser

Damn, Is there anyway to get a close button? You could use a background task, which is started from the omxplayer wrapper script. There should be a way to detect a touch on the screen, if nothing else works you can read the raw input data from the touch device. Or, check the mouse cursor position. ...
by karlkiste
Wed Jan 08, 2014 5:39 pm
Forum: Advanced users
Topic: Running Raspberry on 3.3 V
Replies: 33
Views: 21776

Re: Running Raspberry on 3.3 V

EUA wrote:I run my Raspberry PI modal A with just 3.0v on 3.3v rail without any single issue.
What about the 5V rail? Is it also on 3.0V?
by karlkiste
Sat Dec 14, 2013 4:32 pm
Forum: Graphics, sound and multimedia
Topic: Using the Raspberry as remote "monitor"
Replies: 2
Views: 3067

Re: Using the Raspberry as remote "monitor"

Playing video on the notebook means to uncompress the video. Uncompressed video, like on HDMI for example, has a bandwidth of something like 4 Gigabit. The raspberry can read about 0.05 Gigabit over its network plug. Therefore, all attempts to send uncompressed video over LAN, even wired, will not y...
by karlkiste
Sat Dec 14, 2013 2:13 pm
Forum: Graphics, sound and multimedia
Topic: Just showing off: LEDs
Replies: 3
Views: 791

Re: Just showing off: LEDs

Err, well. Ok, can't deny that, it is expensive ;-)
by karlkiste
Sat Dec 14, 2013 2:02 pm
Forum: Graphics, sound and multimedia
Topic: Just showing off: LEDs
Replies: 3
Views: 791

Just showing off: LEDs

80 custom circuit boards, each with 40 RGB-LEDs and a PIC18F25K22 controller, connected to a raspberry pi which acts as master controller and network interface, makes a nice LED screen. Height: 1.2 meters=4 feet.

Greets,
Kiste
by karlkiste
Mon Dec 09, 2013 5:08 am
Forum: Troubleshooting
Topic: Pi being powered through usb not micro usb
Replies: 5
Views: 895

Re: Pi being powered through usb not micro usb

The "bad guy" in this case is the USB hub. It is not supposed to feed current back to the input. Some cheap devices do anyway. I've been shorting a diode inside a hub once to do just that: feed the pi backwards. It's officially not recommended for the input fusing is bypassed, but usually there's no...
by karlkiste
Mon Dec 09, 2013 5:01 am
Forum: HATs and other add-ons
Topic: 1µ amp
Replies: 3
Views: 2275

Re: 1µ amp

Ultimately microampere range should be feasible with PICs too. Definitely, it is. If you only need to wake up on external digital signals, you can go down to a few nanoamperes. If you need to regularly check something actively, some of the "modern" PICs have a "Ultra-low-power-wakeup" feature, whic...
by karlkiste
Fri Nov 22, 2013 7:10 am
Forum: Automation, sensing and robotics
Topic: Reading a 7-segment display from controller
Replies: 15
Views: 4684

Re: Reading a 7-segment display from controller

If each of the digits has its own 74HC164, chances are good that the display in fact is *not* multiplexed, and you can just read the status of all of the 21 (3x7) segment lines without any timing problems. Then there's the question of how you want to read that many bits. Serializing or demultiplexin...
by karlkiste
Wed Nov 20, 2013 6:05 am
Forum: Gaming
Topic: Could I power my PRi from this?
Replies: 9
Views: 1686

Re: Could I power my PRi from this?

It's enough to power about 40 model B pi's. I'd say, it's a bit of overkill. You need the GND (0 volt) and 5 volt connectors, and connect them to the appropriate places on the pi. Preferably the micro-USB-connector for it has input protection. But the power pins in the GPIO header do also work, even...
by karlkiste
Tue Nov 19, 2013 9:31 am
Forum: General discussion
Topic: Serial Video Output, multiple TFT
Replies: 8
Views: 2800

Re: Serial Video Output, multiple TFT

I've found this TFT http://bit.ly/1fR9dBG with serial interface, but it hasn't buffer memory I read "With built in controller and memory ... No overhead on firmware/processor for refreshing" like it does have memory. Real-time display data is usually sent via TTL, LVDS or some special sort of seria...
by karlkiste
Mon Nov 18, 2013 8:27 pm
Forum: Camera board
Topic: 2 camera boards for one RPi
Replies: 8
Views: 2379

Re: 2 camera boards for one RPi

Err, the signals on some traces of the camera cable are quite fast. They may not like to be forked to a powered-down transmitter.

You can try, but I presume you won't get far with this approach.

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