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by karlkiste
Mon Dec 09, 2013 5:01 am
Forum: HATs and other add-ons
Topic: 1µ amp
Replies: 3
Views: 2362

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: 5282

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: 1882

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: 3107

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: 2568

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.
by karlkiste
Mon Nov 18, 2013 6:34 pm
Forum: Other projects
Topic: Is it possible to get my RPi to tell Windows it is a device?
Replies: 19
Views: 5735

Re: Is it possible to get my RPi to tell Windows it is a dev

Those cables do exist (e.g. http://www.datapro.net/products/usb-2-0 ... cable.html ), but you can't simulate keyboard and/or mouse using them afaik.

Why don't you want to use rdesktop via network? It does all you're asking for.
by karlkiste
Mon Nov 18, 2013 5:16 pm
Forum: Camera board
Topic: 2 camera boards for one RPi
Replies: 8
Views: 2568

Re: 2 camera boards for one RPi

I've been thinking about how I would do a day/night camera.

I'd buy a IR-cut filter. They're not very cheap, you can get them from photography shops. Using a servo, I'd move the filter in front of the lens to get right colors during the day, and remove it at night to make use of IR illumination.
by karlkiste
Mon Nov 18, 2013 5:11 pm
Forum: Automation, sensing and robotics
Topic: Reading a 7-segment display from controller
Replies: 15
Views: 5282

Re: Reading a 7-segment display from controller

A little appendix to the previous post which I agree with in general:

Depending on the multiplexing frequency of the display, it might even be impossible to read it from the pi using tapped signals. Often, displays are multiplexed at 100Hz or so, that would be ok. It could however be much higher.
by karlkiste
Mon Nov 18, 2013 12:01 pm
Forum: Other projects
Topic: Is it possible to get my RPi to tell Windows it is a device?
Replies: 19
Views: 5735

Re: Is it possible to get my RPi to tell Windows it is a dev

Act as a USB device: Impossible. The USB hardware cannot be set to client mode. *Cough* http://www.raspberrypi.org/phpBB3/viewtopic.php?f=63&t=15696#p159641 From that link: "Yes, Model-A should be able to work in slave mode." We're talking here about a model B, I think. On a model A, it is not easy...
by karlkiste
Mon Nov 18, 2013 10:51 am
Forum: Other projects
Topic: Is it possible to get my RPi to tell Windows it is a device?
Replies: 19
Views: 5735

Re: Is it possible to get my RPi to tell Windows it is a dev

Act as a USB device: Impossible. The USB hardware cannot be set to client mode.

Use the Pi as a "remote Windows workstation" via network: easy. Just install rdesktop and connect to the windows machine.
by karlkiste
Sun Nov 17, 2013 4:02 pm
Forum: General discussion
Topic: Power supply problems (too many amps)
Replies: 8
Views: 2539

Re: Power supply problems (too many amps)

The power supply tries it's best to keep the output at 13.5V. It gives the current it is asked for. If the motor asks for 3A, 3A will be running until the power supply switches off or dies. The power supply could reduce the current by reducing the voltage, but that's not its job. The supply is fully...
by karlkiste
Sun Nov 17, 2013 3:42 pm
Forum: Troubleshooting
Topic: GPIO Pings re-assigment?
Replies: 9
Views: 1971

Re: GPIO Pings re-assigment?

If your RS232 sending device sends only 0V/3.3V, but on a DB9 connector, you still cannot connect it directly. The voltage levels may be right, but the logic is not. You'll need an inverter at least. RS232 defines a "1" as -3..-15V and "0" as +3..+15V, while the pi assumes 1 to be +2.5V..+3.3V and 0...
by karlkiste
Sun Nov 17, 2013 3:31 pm
Forum: Advanced users
Topic: Running Raspberry on 3.3 V
Replies: 33
Views: 24022

Re: Running Raspberry on 3.3 V

The risk of damaging the Pi is minimal and you certainly don't want to risk losing your payload because the batteries died before you got to it. The batteries should not be affected. If 5V and 3.3V rails are wired to 3.3V both, the LDO shouldn't consume more than a few milliamperes (max. 10 mA says...
by karlkiste
Mon Nov 04, 2013 3:49 pm
Forum: General discussion
Topic: Serial Video Output, multiple TFT
Replies: 8
Views: 3107

Re: Serial Video Output, multiple TFT

A good quality HDMI splitter is likely more expensive than three extra pis...
by karlkiste
Sat Nov 02, 2013 6:39 pm
Forum: Other projects
Topic: Portable case: Shortening the micro usb plug.
Replies: 7
Views: 2600

Re: Portable case: Shortening the micro usb plug.

Mikumiku747 wrote: Thanks for all the great responses, but to those who suggested the 5v rail, I'm already using that as a power source for my screen.
So, cut the power cable to the screen, and feed the 5V to this cable. It will feed the display and the pi.
by karlkiste
Sat Nov 02, 2013 6:34 pm
Forum: Raspbian
Topic: GPIO to SYSFS
Replies: 3
Views: 1453

Re: GPIO to SYSFS

The file is not updated, as it is no file in that sense.

Only if read, the value that seems to come from the file ist generated by the kernel.
by karlkiste
Sat Nov 02, 2013 8:19 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Using GPIO to multiple switches (as well as sensors)
Replies: 14
Views: 4460

Re: Using GPIO to multiple switches (as well as sensors)

There are flow sensors using doppler effect, which do not obstruct the flow. They can actially measure the speed of the water, but they're not really cheap I think.
by karlkiste
Sat Nov 02, 2013 8:02 am
Forum: Advanced users
Topic: Running Raspberry on 3.3 V
Replies: 33
Views: 24022

Re: Running Raspberry on 3.3 V

I've read the link, and think it might be possible. There should however be no need to desolder the regulator - it should be possible to just feed 3.3V to both the 3.3 and 5V pins on the GPIO header. The regulator shouldn't mind having input and output at the same level as long as it's not higher th...
by karlkiste
Sat Nov 02, 2013 7:50 am
Forum: Raspbian
Topic: Installing flash possible?
Replies: 9
Views: 1729

Re: Installing flash possible?

To my knowledge, the original adobe flash player is discontinued, no new versions can be expected. There's a linux version, but afaik only for intel platform.

Therefore, I think you are right: No chance for flash, at least not from adobe.

You could try gnash or swfdec or something.
by karlkiste
Sat Nov 02, 2013 7:46 am
Forum: Troubleshooting
Topic: Unstable USB external drive
Replies: 6
Views: 1441

Re: Unstable USB external drive

"entirely self-powered" = not drawing any power from the pi. Not for the drive itself, and not for any part of the controller or interface electronic.
by karlkiste
Sat Nov 02, 2013 7:08 am
Forum: Other projects
Topic: Portable case: Shortening the micro usb plug.
Replies: 7
Views: 2600

Re: Portable case: Shortening the micro usb plug.

Yes, you can "skin" the plastic of a plug to be able to bend it shorter than usual.

Other (not officially reccomended) solder-free solutions are back-powering through one of the USB-ports or the power pins at the GPIO.
by karlkiste
Fri Nov 01, 2013 4:57 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Using GPIO to multiple switches (as well as sensors)
Replies: 14
Views: 4460

Re: Using GPIO to multiple switches (as well as sensors)

A little off-topic to this forum, but... Be careful when you have current go through water. I fear, that aluminium *will* corrode when conducting current through water. High-grade stainless steel might be a better choice, but the only material which will undoubtedly be absolutely safe is platinum. A...
by karlkiste
Thu Oct 31, 2013 9:03 pm
Forum: Deutsch
Topic: Neues Modell?
Replies: 11
Views: 3280

Re: Neues Modell?

Die stehen jetzt jeweils in vierer- oder fünferpacks in verschiedenen Elektronikmärkten und bespielen dort Ausstellungsstücke wie Fernseher und Stereoanlagen mit HDMI-Eingang.
by karlkiste
Thu Oct 31, 2013 8:14 pm
Forum: General discussion
Topic: Can/should the raspi control 100+ LEDs?
Replies: 12
Views: 4821

Re: Can/should the raspi control 100+ LEDs?

That strip is not good for the boblight thing. It can change color, but the whole strip has always only one color. With the WS2801-type LEDs, each LED can have its own color.
by karlkiste
Thu Oct 31, 2013 7:16 pm
Forum: General discussion
Topic: Can/should the raspi control 100+ LEDs?
Replies: 12
Views: 4821

Re: Can/should the raspi control 100+ LEDs?

A buffer is simply a buffer, nothing raspi-specific. I use a 74HCT245 to shift the 3V3 output level to 5V and make eight outputs follow one GPIO pin.

The raspi cannot dim LEDs, the WS2801-LEDs used for the boblight have a dimming circuit built-in. This circuit can be controlled by the pi.

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