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by ragnarjensen
Tue Jul 30, 2019 6:17 pm
Forum: General discussion
Topic: Disk activity light.
Replies: 2
Views: 297

Re: Disk activity light.

I've written some programs that blinks GPIO-connected LEDs on mass storage and network activity.

https://github.com/RagnarJensen/PiLEDlights
by ragnarjensen
Fri Mar 29, 2019 8:27 pm
Forum: General discussion
Topic: Những lý do nên đăng ký lắp mạng Fpt ?
Replies: 1
Views: 132

Re: Disk activity light

I wrote a program, some years ago, to do that.
https://github.com/RagnarJensen/PiLEDlights

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Ragnar
by ragnarjensen
Sat Oct 27, 2018 9:28 pm
Forum: General discussion
Topic: Raspberry Pi Magnetic Field Tolerance
Replies: 16
Views: 1188

Re: Raspberry Pi Magnetic Field Tolerance

viewtopic.php?f=41&t=72015
A stock RPi in a MRI scanner managed about 1T, then the ethernet connector stopped working (there's small ferrite cores in it.)
He substituted ethernet and USB connectors for non-magnetic ones and went over 3T.

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Ragnar
by ragnarjensen
Sat Oct 27, 2018 8:34 pm
Forum: General discussion
Topic: Need a voltage output when audio playing
Replies: 1
Views: 231

Re: Need a voltage output when audio playing

Have a look in the /proc/asound/... directory tree. Every audio sub-channel has a "hw_params" file in there. When you "cat" that file, it returns either the word "closed" or the audio format it's currently using. Soundcard 0 is playing: $ cat /proc/asound/card0/pcm0p/sub0/hw_params access: MMAP_INTE...
by ragnarjensen
Mon Sep 17, 2018 6:36 pm
Forum: Beginners
Topic: 3W 850nm leds working voltage?
Replies: 33
Views: 6053

Re: 3W 850nm leds working voltage?

I have a bunch of these LEDs. I use them to give some surveillance cameras night vision. They are 1W, pulling about 350 mA when going full tilt. The potentiometer does not adjust the brightness, it is used to adjust the sensitivity of the light sensor (how dark it should be for the LED to turn on). ...
by ragnarjensen
Mon Jun 25, 2018 6:46 pm
Forum: General discussion
Topic: 2.4ghz rc receivers
Replies: 6
Views: 2833

Re: 2.4ghz rc receivers

I'm not sure what you actually want to do... but if it's reading RC PWM with the RPI; Using an Arduino, it's silly easy to read the pulses from a RC receiver hooked directly to a digital input. Arduino has a pulseIn() function that returns the pulse width directly, in microseconds. RC_receiver.jpg T...
by ragnarjensen
Fri Jun 22, 2018 9:18 am
Forum: Raspbian
Topic: USB Displaylink
Replies: 67
Views: 39786

Re: USB Displaylink

Hi all, First post here! Welcome! 8-) I wanted to know, what is another recommended usb to hdmi displaylink adapter that will work on my pi? I've used a couple of these; https://www.amazon.com/Display-Monitor-Converter-Graphic-Adapter/dp/B008H4JGII They're sold under a lot of different brand names....
by ragnarjensen
Fri Jun 22, 2018 9:04 am
Forum: Raspbian
Topic: USB Displaylink
Replies: 67
Views: 39786

Re: USB Displaylink

@lordaker It looks like you didn't get all of the Xorg.0.log file, the last part seems to be missing.
by ragnarjensen
Tue Jun 19, 2018 7:58 am
Forum: Raspbian
Topic: USB Displaylink
Replies: 67
Views: 39786

Re: USB Displaylink

EDID is a mechanism that is used by the display adapter and the monitor, where the monitor can tell the display adapter which capabilities it has, e.g. resolutions. For some reason your display adapter is not getting the information it wants from the monitor. Does your VGA cable have all 15 pins? Th...
by ragnarjensen
Mon Jun 18, 2018 10:56 am
Forum: Raspbian
Topic: USB Displaylink
Replies: 67
Views: 39786

Re: USB Displaylink

Hi! All is well, thank you. In the messages from dmesg I see a lot of [ 6.177217] EDID block is all zeroes [ 6.177235] udl 1-1.5:1.0: DVI-I-1: EDID invalid. It looks like the DisplayLink adapter doesn't communicate properly with the monitor. I see in you pictures that you are using a VGA cable. Have...
by ragnarjensen
Thu Jun 14, 2018 9:25 am
Forum: Raspbian
Topic: USB Displaylink
Replies: 67
Views: 39786

Re: USB Displaylink

The X log file doesn't show anything being wrong... The output from the dmesg command? Also, what happens if you swap the physicals screens, 221E2 on DisplayLink and 220SW on HDMI? PS: I'm saying that all my Pis are headless. Headless is when a computer doesn't have any screen at all, i.e. I'm unabl...
by ragnarjensen
Wed Jun 13, 2018 6:07 pm
Forum: Raspbian
Topic: USB Displaylink
Replies: 67
Views: 39786

Re: USB Displaylink

What does the X log file say? It's in /var/log/Xorg.0.log on my Raspbian systems.
Also the output from the dmesg command could be interesting.

Note! I don't run USB DisplayLink any longer myself. All my Pis are headless nowadays, so I can't test anything.
by ragnarjensen
Wed Jun 13, 2018 9:50 am
Forum: Raspbian
Topic: USB Displaylink
Replies: 67
Views: 39786

Re: USB Displaylink

I have googled a little on your Kensington K33907 DisplayLink adapter.
Apparently it only supports resolutions up to 1440 x 1050.

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Ragnar
by ragnarjensen
Tue Jun 12, 2018 3:56 pm
Forum: Raspbian
Topic: USB Displaylink
Replies: 67
Views: 39786

Re: USB Displaylink

And if you have a subsection with Modes in there?

Code: Select all

SubSection	"Display"
    		Modes	"1680x1050"
EndSubSection
I have never had to use the Randr extension myself.

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Ragnar
by ragnarjensen
Mon Jun 11, 2018 12:28 pm
Forum: Raspbian
Topic: USB Displaylink
Replies: 67
Views: 39786

Re: USB Displaylink

The keyword to set screen resolutions is "Modes"
The "Mode" keyword is something very different.

Have you tried without the Subsection Display?

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Ragnar
by ragnarjensen
Mon Jan 29, 2018 9:58 am
Forum: Raspbian
Topic: USB Displaylink
Replies: 67
Views: 39786

Re: USB Displaylink

I think the USB Displaylink driver is included in Raspbian nowadays. You shouldn't have to build it yourself.
As far as I know, the driver only supports USB2 devices. There exists an USB3 driver for Ubuntu, but it's partly closed source and only runs on x86.

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Ragnar
by ragnarjensen
Sat Aug 05, 2017 9:22 pm
Forum: Beginners
Topic: Switch audio output in real time?
Replies: 1
Views: 533

Re: Switch audio output in real time?

A single stereo track. Left channel to the speaker in the prop and right channel to the speaker behind the victim.
No need to switch outputs and it would make the overlap easy to do, too.

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Ragnar
by ragnarjensen
Sat Apr 15, 2017 7:03 pm
Forum: General discussion
Topic: Closing the pi
Replies: 10
Views: 1317

Re: Closing the pi

I have the clear version of that case. On the inside of the lid there are four posts for the camera board.
canakit_case_camposts.jpg
Camera board pressed on to posts
canakit_case_camposts.jpg (62.33 KiB) Viewed 1005 times
The lens peeks out through one of the holes in the raspberry logo.
canakit_case_cam_in_lid.jpg
RaspiCam in Canakit case
canakit_case_cam_in_lid.jpg (62.84 KiB) Viewed 1005 times
The case has slots on all sides for flat cables.
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Ragnar
by ragnarjensen
Sat Mar 11, 2017 1:14 pm
Forum: Beginners
Topic: External led status lights.possible?
Replies: 14
Views: 20455

Re: External led status lights.possible?

When Raspbian went from Wheezy to Jessie, things changed. The Pi3 introduced further changes. This might help you getting the serial console going: http://spellfoundry.com/2016/05/29/configuring-gpio-serial-port-raspbian-jessie-including-pi-3/ https://www.abelectronics.co.uk/kb/article/1035/raspberr...
by ragnarjensen
Sun Oct 16, 2016 8:10 pm
Forum: Beginners
Topic: Help with VU meter
Replies: 1
Views: 718

Re: Help with VU meter

The command line program arecord will display a simple VU meter if you use its verbose flag twice or more.

Code: Select all

arecord -vv  ...
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Ragnar
by ragnarjensen
Thu Oct 06, 2016 11:40 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: LEDs
Replies: 4
Views: 925

Re: LEDs

Maybe connect a LED to the Tx pin?
viewtopic.php?p=736408#p736408

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Ragnar
by ragnarjensen
Wed Oct 05, 2016 7:46 pm
Forum: Troubleshooting
Topic: RPI2 Activity and HDD LED Reassign?
Replies: 8
Views: 2344

Re: RPI2 Activity and HDD LED Reassign?

Haemogoblin wrote:Fantastic will those commands work straight off from booting up in to console?
They can be made to start automatically at boot, yes.
I have added the needed start scripts to the repository, in the folder initscripts.

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Ragnar
by ragnarjensen
Sun Oct 02, 2016 1:11 pm
Forum: Troubleshooting
Topic: RPI2 Activity and HDD LED Reassign?
Replies: 8
Views: 2344

Re: RPI2 Activity and HDD LED Reassign?

I've written some small programs that might help you.
https://github.com/RagnarJensen/PiLEDlights

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Ragnar
by ragnarjensen
Mon Sep 12, 2016 7:01 am
Forum: General programming discussion
Topic: Can we control the on-board leds
Replies: 59
Views: 124832

Re: Can we control the on-board leds

rern wrote:@ragnarjensen
After hours of seacrhing for GPIO LED for USB drive, your code is the only one I've found that do exactly I want. Please advice how to make it works on ArchLinux.
I'm sorry, but I have never used ArchLinux.
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Ragnar
by ragnarjensen
Mon Jan 11, 2016 10:10 pm
Forum: Advanced users
Topic: How long have you run your raspi for?
Replies: 42
Views: 15689

Re: How long have you run your raspi for?

Code: Select all

[email protected]:~$ uptime
 22:59:20 up 688 days, 43 min,  2 users,  load average: 0.09, 0.06, 0.02
Model B Rev 2 that is DNS and DHCP server, DynDNS updater and monitors an UPS.
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Ragnar

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