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by KnarfB
Mon Apr 01, 2019 12:55 pm
Forum: Beginners
Topic: usb master and slave port
Replies: 2
Views: 130

Re: usb master and slave port

the micro USB is power supply only.
for USB boot see https://www.raspberrypi.org/documentati ... des/msd.md
by KnarfB
Wed Jan 30, 2019 1:33 pm
Forum: Advanced users
Topic: Headless/Internetless Auto Upgrading Programs
Replies: 2
Views: 177

Re: Headless/Internetless Auto Upgrading Programs

Hi Adrian,

you may use udev rules for that:

https://www.raspberrypi.org/forums/view ... 73#p335304

hth

KnarfB
by KnarfB
Thu Jan 17, 2019 1:19 pm
Forum: Deutsch
Topic: autostart
Replies: 5
Views: 1044

Re: autostart

Hallo Peter, ich nehme für sowas gern einen systemd service: https://github.com/FrankBau/raspi-repo-manifest/wiki/systemd#autostart Wenn Skripte nicht gehen liegt es oft daran, dass die Umgebung beim autostart eine andere ist als die shell in der man vorher testet. Alle Pfade sollten absolute Pfade ...
by KnarfB
Mon Jan 07, 2019 8:36 pm
Forum: Graphics, sound and multimedia
Topic: Photo stitching for high resolution all-sky camera
Replies: 3
Views: 672

Re: Photo stitching for high resolution all-sky camera

Hi jzief, all-sky night camera implies long exposure times and synchronized simultaneous exposures. This raises the question how to connect multiple cameras? Are you thinking of multiple pis? or a single pi remotely controlling real cameras over USB? I use my DSLR for occasional astro photography an...
by KnarfB
Mon Oct 22, 2018 8:29 pm
Forum: General discussion
Topic: cumulative time error
Replies: 1
Views: 287

Re: cumulative time error

You could install a cron job which runs every minute. The cron job triggers your task for a fixed number of times (600) using root.after or such. Make the after period a little smaller than 100 ms such that your tasks takes only 59.x seconds for its 600 executions. Same principles as here https://en...
by KnarfB
Mon Oct 22, 2018 8:08 pm
Forum: Beginners
Topic: long-term looping operation in remote location
Replies: 1
Views: 243

Re: long-term looping operation in remote location

I would use the watchdog in any long-term running scenario. Once activated, the watchdog device must be periodically reset. If was not reset during a timeout period, it will reboot the system.
Anyway, I would double-check for reasons why your playback loop stops so often.

hth

KnarfB
by KnarfB
Mon Oct 22, 2018 7:42 pm
Forum: Bare metal, Assembly language
Topic: Optimizing data structures for NEON
Replies: 4
Views: 2431

Re: Optimizing data structures for NEON

Isn't this way of organizing things more efficient ? So i guess NEON could load a pointer to the first objA and objB then do a vector operation on them since they are contiguous in memory? Yes, you're right. When I put your code into a file int obA[4]; int obB[4]; int test() { obA[0] += obB[0]; obA...
by KnarfB
Fri Sep 14, 2018 4:31 pm
Forum: Automation, sensing and robotics
Topic: Need help with setting up Pressure Sensor with Pi
Replies: 1
Views: 627

Re: Need help with setting up Pressure Sensor with Pi

Hi Mega524, > First, what are the four channels reading, and how do I extract the Pressure reading from this data? the ADV1115 is a 4-channel analog digital voltage converter. Its sensitivity is programmable. The code says GAIN=1. according to the data sheet this means that a voltage of 4.096V yield...
by KnarfB
Thu Sep 06, 2018 8:47 pm
Forum: Automation, sensing and robotics
Topic: Project advice on using analog accelerometers with an ADC
Replies: 5
Views: 1003

Re: Project advice on using analog accelerometers with an ADC

Hi Ross, what do you think is the advantage of using a Raspi with Linux OS? When doing real-time tasks with several hundred sps and a stringent timing, I would rather use a microcontroller and coding in C. You might want to take a look at STM32F303VC (discovery board) or similar. When using I2C SPI ...
by KnarfB
Wed Aug 22, 2018 3:50 pm
Forum: Beginners
Topic: CanBus can_frame address help
Replies: 2
Views: 372

Re: CanBus can_frame address help

Hi,
I would recommend starting with the can-utils command line tools (https://elinux.org/Can-utils) like candump etc...
They are open source, so you may get some insight by studying the sources and reading here: https://www.kernel.org/doc/Documentatio ... ng/can.txt
hth
KnarfB
by KnarfB
Wed Aug 22, 2018 3:19 pm
Forum: Networking and servers
Topic: Can’t connect from outside network
Replies: 6
Views: 538

Re: Can’t connect from outside network

What is the IP address of your server? Is it a public IPv4 address?
by KnarfB
Wed Aug 15, 2018 8:04 am
Forum: Camera board
Topic: PiCam detection
Replies: 7
Views: 902

Re: PiCam detection

Hi nhantd95, sorry for the delayed answer, I was on vacation. You capture a picture A and shortly afterwards another picture B. If A and B are identical --> no motion. If A and B differ --> motion (because something has changed/moved in the scene). In practice you have to make decisions about the ti...
by KnarfB
Fri Jul 20, 2018 9:39 am
Forum: Camera board
Topic: either raspistill or raspivid is not in native resolution at 2592*1944 (ov5647)
Replies: 17
Views: 1697

Re: either raspistill or raspivid is not in native resolution at 2592*1944 (ov5647)

Thats a surprise. I was thinking of the checkerboard patterns where one can count out the pixels and check whats missing and/or what was interpolated. According to the docs, 503D,81 should do that, strange. Did you try more combinations 82, 83, ... there may be a typo in the docs. The idea was to si...
by KnarfB
Fri Jul 20, 2018 6:02 am
Forum: Camera board
Topic: either raspistill or raspivid is not in native resolution at 2592*1944 (ov5647)
Replies: 17
Views: 1697

Re: either raspistill or raspivid is not in native resolution at 2592*1944 (ov5647)

Wouldn't it make sense to activate the sensors test pattern feature by setting ov5647 reg 0x503D?
Then, your measurments will be independent of optical targets and pixel peeping is much easier.
My v1.3 cam module is broken, so I cannot test it myself. hth KnarfB
by KnarfB
Thu Jul 19, 2018 4:44 pm
Forum: Advanced users
Topic: [RESOLVED] Verifying transmission complete on Tx/Rx
Replies: 4
Views: 637

Re: Verifying transmission complete on Tx/Rx

Hi David, you cannot be sure for a user mode application because of OS activities which may introduce unwanted delays between your function calls, e.g. under heavy load conditions. If you switch the GPIO back too late, the UART may miss an early reply on the RS485 bus. The overall risk depends on th...
by KnarfB
Thu Jul 19, 2018 1:39 pm
Forum: Camera board
Topic: PiCam detection
Replies: 7
Views: 902

Re: PiCam detection

Hi nhantd95, I would use the OpenCV library and a little C++ programming for that (Python works too). Capture two picturea A and B and compute the sum of pixelwise absolute differences ( norm(A-B) ). If the resulting value is small (in plain theory: 0) the pictures are identical -> no motion. If the...
by KnarfB
Thu Jul 19, 2018 1:30 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Setting register bit
Replies: 14
Views: 1282

Re: Setting register bit

Hi sondeben, I have not worked with those chips, but take a look at the datasheet (SNOSCZ9–MAY 2016) page 21 figure 16 and 17 (i2c write and read) and take a look at 7.6.1 Register List. All registers are 16-bit. So you need ro read/write two bytes of data (read_word_data...). One cannot address a s...
by KnarfB
Wed Jul 18, 2018 1:47 pm
Forum: Beginners
Topic: Missing smbpasswd and testparm commands in raspbian
Replies: 1
Views: 495

Re: Missing smbpasswd and testparm commands in raspbian

Did you install samba?

Code: Select all

sudo apt install samba
use

Code: Select all

sudo /etc/init.d/samba restart
aftter editing smb.conf

Works for me with a Win10 client PC.
by KnarfB
Wed Jul 18, 2018 1:23 pm
Forum: Graphics, sound and multimedia
Topic: Streaming from netcat to VLC
Replies: 2
Views: 1836

Re: Streaming from netcat to VLC

use tcp/h264://192.168.2.111:8080 with your ipv4 address and port. Although I would prefer RTSP streaming: raspi: raspivid -n -ih -t 0 -w 1280 -h 720 -b 1000000 -fps 30 -o - | cvlc -vvv stream:///dev/stdin --sout '#rtp{sdp=rtsp://:8080/}' :demux=h264 client VLC ue media URL: rtsp://192.168.2.111:8080/
by KnarfB
Wed Jul 18, 2018 10:29 am
Forum: Graphics, sound and multimedia
Topic: Raspberry and a vintage video ADC
Replies: 4
Views: 719

Re: Raspberry and a vintage video ADC

Hi pieroc91, I made some tests with a kernel module, but a continous sampling rate of 6 MHz seems to be too fast to be achieved in software (even with direct MMIO register access in assembler). This is consistent with other projects I have seen like https://github.com/richardghirst/Panalyzer having ...
by KnarfB
Mon Jul 16, 2018 4:58 am
Forum: Graphics, sound and multimedia
Topic: Raspberry and a vintage video ADC
Replies: 4
Views: 719

Re: Raspberry and a vintage video ADC

Hi pieroc91, wow, you got a great piece of hardware. Did I get it right: The Raspi needs to read a 8-bit ADC data stream with an externeal 6 MHz clock and hsync+vsync pulses. The Raspi doesn't have a dedicated digital video input interface besides the camera connector which is IMHO hard to play with...
by KnarfB
Sun Jul 15, 2018 8:12 pm
Forum: Camera board
Topic: either raspistill or raspivid is not in native resolution at 2592*1944 (ov5647)
Replies: 17
Views: 1697

Re: either raspistill or raspivid is not in native resolution at 2592*1944 (ov5647)

JPEG compresses MCUs aka "macroblocks". A macroblock typically comprises of 16x16 pixels. But, 1944 is not a multiple of 16. It seems the the video cuts 8 pixel columns off at the right hand side. The macroblock size is related to color space conversion, subsampling and the size of the 8x8 DCT trans...
by KnarfB
Sun Jul 15, 2018 7:59 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: UART read problem
Replies: 9
Views: 882

Re: UART read problem

What software (terminal program) are you using at the PC side for testing?
Make sure that flow control is disabled at the PC side software.
You could shortcut RX and TX pins at the Raspi and check if you get an echo if you write something.

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