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by PiGraham
Wed Dec 30, 2020 11:21 am
Forum: Python
Topic: How to have accurate time.sleep()
Replies: 13
Views: 539

Re: How to have accurate time.sleep()

Out of curiosity I did a quick test of raspistill -tl time-lapse option $ raspistill -tl 5000 -t 30000 -o image%04d.jpg with these results: -rw-r--r-- 1 pi pi 2699301 2020-12-30 10:53:09.378878731 +0000 image0000.jpg -rw-r--r-- 1 pi pi 2697500 2020-12-30 10:53:14.441429941 +0000 image0001.jpg -rw-r-...
by PiGraham
Tue Dec 29, 2020 12:36 pm
Forum: Python
Topic: How to have accurate time.sleep()
Replies: 13
Views: 539

Re: How to have accurate time.sleep()

For timelapse with raspistill have you read the docs?
https://www.raspberrypi.org/documentati ... melapse.md

Or in Python, using picamera:
https://picamera.readthedocs.io/en/rele ... -sequences
by PiGraham
Sun Dec 27, 2020 10:19 am
Forum: Python
Topic: Slides how on second pi
Replies: 1
Views: 74

Re: Slides how on second pi

You could look at inotifywait to run a command whenever a file or folder changes. If you share a folder on RPi A with NFS, Samba etc and save new image files there from RPI B then a script usinf inotifywait could react to the save of a new image and run a command such as fbi to display the new image.
by PiGraham
Wed Dec 23, 2020 9:02 pm
Forum: Beginners
Topic: Can I use tablet as pi display, and use keyboard connected to pi
Replies: 9
Views: 317

Re: Can I use tablet as pi display, and use keyboard connected to pi

ETA Prime shows how to use an Android device with HDMI capture as a monitor for your PI (oe any HDMI output device)

https://www.youtube.com/watch?v=nui8kXvUAys
by PiGraham
Wed Dec 23, 2020 10:12 am
Forum: Automation, sensing and robotics
Topic: Break Beam Sensor Sensing distance 2 metres
Replies: 15
Views: 430

Re: Break Beam Sensor Sensing distance 2 metres

Thank you for all the replies. I had hoped to avoid the larger and expensive more industrial type solutions. This is intended as a game for my kids, I have hoped to attach the sensor to a small 2mX2m frame and detect when a ball passes through it Do you want to detect the ball passing ANYWHERE with...
by PiGraham
Tue Dec 22, 2020 8:55 pm
Forum: Automation, sensing and robotics
Topic: Break Beam Sensor Sensing distance 2 metres
Replies: 15
Views: 430

Re: Break Beam Sensor Sensing distance 2 metres

A possible alternative is cheap laser diode modules and photo transistors in a black tubes to screen ambient light. You can find those for ~£1.50 each on eBay. The alignment will be critical though so it could be a lot of trouble where it might get knocked by a ball.
by PiGraham
Tue Dec 22, 2020 8:50 pm
Forum: Automation, sensing and robotics
Topic: Break Beam Sensor Sensing distance 2 metres
Replies: 15
Views: 430

Re: Break Beam Sensor Sensing distance 2 metres

Search "ir gate sensor"

You should be able to find them around £8 each and they have IR filter and lens and easily do 2m even on sunny days.
by PiGraham
Tue Dec 22, 2020 9:17 am
Forum: General discussion
Topic: Cannot connect to bluetooth audio devices after December update (2020)
Replies: 2
Views: 148

Re: Cannot connect to bluetooth audio devices after December update (2020)

Have you done a full upgrade of an existing PiOS? sudo apt full-upgrade Did you follow all the instructions to remove bluealsa? https://www.raspberrypi.org/blog/new-raspberry-pi-os-release-december-2020/ sudo apt purge bluealsa sudo apt install pulseaudio-module-bluetooth . Now reboot I don't know i...
by PiGraham
Mon Dec 21, 2020 3:10 pm
Forum: General discussion
Topic: Use RPI 4 to extend windows screen (dont want to connect my laptop to the screen with a cable anymore)
Replies: 7
Views: 269

Re: Use RPI 4 to extend windows screen (dont want to connect my laptop to the screen with a cable anymore)

Yes, miracast, or put a FireTV, Chromecast, MS wireless display adapter or similar Streaming HDMI device on the display. Connect to that wirelessly from your PC or your Pi or other device. If this is a 'public' display I'm not sure how any of these cope with contention between users. I suspect it's ...
by PiGraham
Mon Dec 21, 2020 12:54 pm
Forum: Off topic discussion
Topic: Advice on how to setup a new swap device (can you get HDD's any more?)
Replies: 20
Views: 552

Re: Do they even make spinning rust hard drives anymore? advice on how to setup a new swap device

Flash is a lot faster than "spinning rust".
If a USB flash drive lasts "several years" why not just replace it annually for both speed and reliability?
by PiGraham
Fri Dec 18, 2020 9:04 am
Forum: Python
Topic: Loop reacts unexpected
Replies: 7
Views: 238

Re: Loop reacts unexpected

I see, I need to get familiar with threading. Not really; you just need to get to grips with polling properly. Something like ... That should work. The WaitForEdge function should achieve the same and maybe a little bit clearer what's going on. AIUI it could be lower CPU load as well: while True: p...
by PiGraham
Tue Dec 15, 2020 10:56 am
Forum: C/C++
Topic: WHILE loop inside the button event function
Replies: 16
Views: 733

Re: WHILE loop inside the button event function

Use timer events to handle delays in event driven GUI code. Set a call back and start a timer on a button click, or whatever GUI event. In the call back update the UI. Be very cautious using threads to update GUI elements. That is often not thread safe if done naively. Callback typically run in the ...
by PiGraham
Mon Dec 14, 2020 5:29 pm
Forum: Off topic discussion
Topic: What would be the best inexpensive keyboard mouse?
Replies: 33
Views: 1121

Re: What would be the best inexpensive keyboard mouse?

Please be careful with "inexpensive keyboard and mouse" combos while most may work properly with w$, when used in RPi or other Linux SBCs, the mouse movement lags... if there are no lags... the movement is non-linear (more like logarithmic, slow in the middle, faster on the edges) why do ...
by PiGraham
Mon Dec 14, 2020 9:54 am
Forum: Off topic discussion
Topic: What would be the best inexpensive keyboard mouse?
Replies: 33
Views: 1121

Re: What would be the best inexpensive keyboard mouse?

What would be a good keyboard mouse that would fit these conditions? Works with linux(rpi),mac, and windows is a keyboard mouse combo I will be using this mostly with windows 10 and rpi Thanks What sort of quality are you after and what do you call cheap, less than £10? There are countless cheap ke...
by PiGraham
Sat Dec 12, 2020 10:11 pm
Forum: Networking and servers
Topic: VNC doesn't work without an HDMI connection
Replies: 16
Views: 555

Re: VNC doesn't work without an HDMI connection

its not "useless noise"... its a declaration against the OP's topic title... :mrgreen: @OP just set the desktop resolution.... shutdown.... sleep ....and report back in the morning when you reboot... ;) You are right. VNC does work without an HDMI connection, if configured correctly. Forc...
by PiGraham
Sat Dec 12, 2020 11:20 am
Forum: Automation, sensing and robotics
Topic: Checking when food/water bowls are empty?
Replies: 24
Views: 2181

Re: Checking when food/water bowls are empty?

You could try some AI detection. https://duckduckgo.com/?q=tensorflow+hedgehog+detector&ia=software https://medium.com/@dana.yu/training-a-custom-object-detection-model-41093ddc5797 Here's a weighing scale project using RPi https://tutorials-raspberrypi.com/digital-raspberry-pi-scale-weight-sens...
by PiGraham
Fri Dec 11, 2020 11:23 am
Forum: General discussion
Topic: Newbie: Pi4 or 400 for engineer partner?
Replies: 23
Views: 1076

Re: Newbie: Pi4 or 400 for engineer partner?

Pi200 would only be half as good! But maybe only half as big and cost half as much? lol I agree with drgeoff about the addictive thing. Possibly a Big Pi plot to control the world? I personally know about 2 dozen techies with Pi4 and they are very happy. I also know a couple younguns with 400 now a...
by PiGraham
Fri Dec 11, 2020 9:31 am
Forum: Advanced users
Topic: Model with least power consuption?
Replies: 12
Views: 709

Re: Model with least power consuption?

People who won't say what they want to achieve tend to get less useful answers from forums Please a bit less "attitude".... :mrgreen: remember rule #1, be nice to each other.... not that I disagree with your statement, but its a bit harshly stated. I meant to be constructive not harsh. Th...
by PiGraham
Thu Dec 10, 2020 5:48 pm
Forum: General discussion
Topic: Newbie: Pi4 or 400 for engineer partner?
Replies: 23
Views: 1076

Re: Newbie: Pi4 or 400 for engineer partner?

davidcoton wrote:
Thu Dec 10, 2020 5:46 pm

There is no Pi200 (typo I think). The Pi4 and Pi400 official kits are equivalent in their completeness.
Yes, thanks. Typo. Pi200 would only be half as good!
by PiGraham
Thu Dec 10, 2020 5:08 pm
Forum: General discussion
Topic: Newbie: Pi4 or 400 for engineer partner?
Replies: 23
Views: 1076

Re: Newbie: Pi4 or 400 for engineer partner?

Note that subject to sorting out the display issue (no TV, may need to SSH VNC but may not have an SD card writer) the Pi400 kit has what you need to attain maximum Pi on Christmas morning, which may be a plus.
by PiGraham
Thu Dec 10, 2020 5:02 pm
Forum: Advanced users
Topic: Model with least power consuption?
Replies: 12
Views: 709

Re: Model with least power consuption?

People who won't say what they want to achieve tend to get less useful answers from forums
by PiGraham
Thu Dec 10, 2020 1:33 pm
Forum: Advanced users
Topic: Model with least power consuption?
Replies: 12
Views: 709

Re: Model with least power consuption?

I will use a Raspberry headless operating for some simple task and don''t need much computing power. Which Rasberry PI model must be used if I want to run the least possible power consumption? (zero, compute model?) I'm aware of flash memory etc, but my question is about power consumption. Thanks f...
by PiGraham
Thu Dec 10, 2020 1:24 pm
Forum: General discussion
Topic: Newbie: Pi4 or 400 for engineer partner?
Replies: 23
Views: 1076

Re: Newbie: Pi4 or 400 for engineer partner?

If you are OK with the price of the Pi 400 kit I suggest that. I can't believe anyone techie wouldn't be delighted with one of those. It is a think of beauty. Now he might prefer a 4B for some project or other, but that's OK. He can develop the project on the Pi400 and later on run it on the Pi4B th...
by PiGraham
Wed Dec 09, 2020 1:29 pm
Forum: Automation, sensing and robotics
Topic: 2 independent Steppers, using 1 Driver
Replies: 12
Views: 586

Re: 2 independent Steppers, using 1 Driver

We do know what it will do, it will move the motor to the same phase position as the other motor. Yes if the motors were free to run with no load, but as they will be driving a worm gear they would need to step correctly to be able to move, they are unlikely to be able to move to the correct positi...
by PiGraham
Wed Dec 09, 2020 11:48 am
Forum: Automation, sensing and robotics
Topic: 2 independent Steppers, using 1 Driver
Replies: 12
Views: 586

Re: 2 independent Steppers, using 1 Driver

One point no one has mentioned is that the output of the stepper driver will cycle the the output pins in a specific pattern to drive the stepper motor . So if you drive one motor to a specific point in the pattern of outputs and then switch to the second motor unless that motor is in exactly the s...

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