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by PiGraham
Fri Dec 06, 2019 8:49 am
Forum: Compute Module
Topic: What else is there besides Raspberry Pi..?
Replies: 19
Views: 667

Re: What else is there besides Raspberry Pi..?

This is the core of the request and the big reason it's not for RPi: But of course for snits and giggles I want to do it myself. But here's the stumbling point: I wish it to be a full Android device. ... compatible with Android, the Google Play Store, and the zillion apps on there. If you want full ...
by PiGraham
Thu Dec 05, 2019 4:55 pm
Forum: Compute Module
Topic: What else is there besides Raspberry Pi..?
Replies: 19
Views: 667

Re: What else is there besides Raspberry Pi..?

Try searching for "system on module android"
by PiGraham
Tue Dec 03, 2019 10:56 am
Forum: Troubleshooting
Topic: GUI without Desktop
Replies: 3
Views: 120

Re: GUI without Desktop

221373 wrote:
Tue Dec 03, 2019 10:14 am
Hi I have program which run and open via Qt application. There is a kind of user interface in window to visualize sensors read and some of buttons to implement some actions.
Maybe this will help to get Qt working on framebuffer without X
https://doc.qt.io/archives/qt-4.8/qvfb.html
by PiGraham
Tue Dec 03, 2019 10:00 am
Forum: Troubleshooting
Topic: GUI without Desktop
Replies: 3
Views: 120

Re: GUI without Desktop

It might help define the problem better if you say what sort of GUI you want? windows, icons buttons and menus?
Something more like a game GUI?

I think you can work without X using PyGame and maybe tkinter.

This may be useful
http://www.karoltomala.com/blog/?p=679
by PiGraham
Thu Nov 21, 2019 10:34 am
Forum: General discussion
Topic: magnetometer for detecting objects
Replies: 4
Views: 278

Re: magnetometer for detecting objects

It also has a fairly sensitive accelerometer, but I wasn't able to detect the ground vibrations of passing cars at 8 metres with that either. It seems MEMS accelerometers could detect traffic if they were close enough, but maybe not suited to remote sensing over many metres. https://www.kickstarter...
by PiGraham
Tue Nov 19, 2019 11:11 am
Forum: Beginners
Topic: Maybe a Dumb Question, But How Can I Lock Down an App?
Replies: 4
Views: 186

Re: Maybe a Dumb Question, But How Can I Lock Down an App?

Thanks W. H. Heydt and rpdom for your prompt replies. I did not receive notification that my post had been approved, nor did I receive any notification of your replies. Good thing I decided to check! :) So maybe my first post did not go quite as planned. My main concern was with the capability of t...
by PiGraham
Tue Nov 12, 2019 2:03 pm
Forum: Wanted
Topic: Engineering Project - Need Help
Replies: 8
Views: 419

Re: Engineering Project - Need Help

OK here’s what I am looking for. A basic knob switch, 4 settings plus off/on switch. Each setting would control a speed to make the light dim up, hold, dim down on a specific timed setting. I'm hoping to hire a hobbiest or student wanting to learn What sort of light? What is the the dimmer for? Is ...
by PiGraham
Tue Nov 12, 2019 12:31 pm
Forum: Other projects
Topic: Wireless Distance Sensing?
Replies: 38
Views: 2226

Re: Wireless Distance Sensing?

You are in effect asking for indoor GPS, which is not a trivial task at all. It's quite difficult. I'm not asking for anything. The OP asks for a hide-and-seek detector system. From a cursory test of BT using RSSI and noting numerous comments on the ineffectiveness of such apps I'm sceptical whethe...
by PiGraham
Tue Nov 12, 2019 9:48 am
Forum: Other projects
Topic: Wireless Distance Sensing?
Replies: 38
Views: 2226

Re: Wireless Distance Sensing?

something to indicate to the user how close (how high/low the RSSI is) you are to the beacon. /Mogens Does that really work? As I mentioned the two Bluetooth finder apps I tried seemed all but useless for locating Bluetooth devices. Maybe it would work better if there were some fixed beacons in kno...
by PiGraham
Tue Nov 12, 2019 9:41 am
Forum: Automation, sensing and robotics
Topic: Distances of two different points in x y z coordinates
Replies: 23
Views: 1577

Re: Distances of two different points in x y z coordinates

I don't think ". I have no restrictions on that device." means "money no object". Still, this is cool if can afford it. Measure whatever you want. https://www.youtube.com/watch?v=KUdbrFOJlO0 Or https://www.youtube.com/watch?v=aq4NLmiJHwk I need to calculate distance between 2 spesific objects (Actu...
by PiGraham
Mon Nov 11, 2019 4:37 pm
Forum: Other projects
Topic: Wireless Distance Sensing?
Replies: 38
Views: 2226

Re: Wireless Distance Sensing?

The big advantage of buying the beacon tags is that they integrate a battery into a neat case and last for a long time. Battery life is over 3 year on default setting. battery CR3032 battery https://www.banggood.com/Waterproof-BBeacon-Module-Module-Card-with-Eddystone-and-Beacon-for-Indoor-Navigatio...
by PiGraham
Mon Nov 11, 2019 8:08 am
Forum: Other projects
Topic: Wireless Distance Sensing?
Replies: 38
Views: 2226

Re: Wireless Distance Sensing?

Searching for "long range uhf rfid reader raspberry pi" gives a few results worth checking out. Nothing specific that might suit this application? There are things like this: https://www.amazon.co.uk/reader-vehicle-parking-application-meters/dp/B018EFLJJI which claim 3 to 5 metres reading range but...
by PiGraham
Sun Nov 10, 2019 9:08 pm
Forum: Other projects
Topic: Wireless Distance Sensing?
Replies: 38
Views: 2226

Re: Wireless Distance Sensing?

deepo wrote:
Sun Nov 10, 2019 6:58 pm
ranges below 2 meters is the norm.
I'd think you can get 1 meter detection range with modest equipment.
The cheap maker kit I've seen is a range of a few centimetres (~2cm)

Can you give examples of kit that works at more than 10cm?
by PiGraham
Sat Nov 09, 2019 4:13 pm
Forum: Automation, sensing and robotics
Topic: Distances of two different points in x y z coordinates
Replies: 23
Views: 1577

Re: Distances of two different points in x y z coordinates

Certainly that sort of 3D from stereo can be done.
As with any triangulation method the accuracy reduces as the separation reduces and the angle becomes very acute.
I think there's a tradeoff because wider separation improves the angle but also changes the view which can make feature matching harder.
by PiGraham
Sat Nov 09, 2019 10:35 am
Forum: Automation, sensing and robotics
Topic: Distances of two different points in x y z coordinates
Replies: 23
Views: 1577

Re: Distances of two different points in x y z coordinates

If it has to be cheap you could try 2 cameras, probably usb so 2 will work on a pi, and determine the distances to the points, from the difference between the images after you have calibrated. You could then use my earlier method with measured angles. Good point. If two cameras are rigidly mounted ...
by PiGraham
Fri Nov 08, 2019 5:06 pm
Forum: Other projects
Topic: Wireless Distance Sensing?
Replies: 38
Views: 2226

Re: Wireless Distance Sensing?

https://gaorfid.com/product/reader-active-usb-receiver-2-45-ghz-rfid/ 20m range used with active tags https://gaorfid.com/devices/rfid-tags-by-frequencies/active-2-45-ghz-rfid-tags/ Or something from eBay https://www.ebay.co.uk/itm/Active-RFID-Electronic-Tag-Reader-Undervoltage-reminder-ABS-For-Navi...
by PiGraham
Fri Nov 08, 2019 1:53 pm
Forum: Automation, sensing and robotics
Topic: Distances of two different points in x y z coordinates
Replies: 23
Views: 1577

Re: Distances of two different points in x y z coordinates

I don't think ". I have no restrictions on that device." means "money no object".

Still, this is cool if can afford it. Measure whatever you want.

https://www.youtube.com/watch?v=KUdbrFOJlO0

Or

https://www.youtube.com/watch?v=aq4NLmiJHwk
by PiGraham
Fri Nov 08, 2019 11:22 am
Forum: Other projects
Topic: Wireless Distance Sensing?
Replies: 38
Views: 2226

Re: Wireless Distance Sensing?

This claims to be BT5.0 Eddystone beacon in a watch format. 1 yr battery life
https://www.amazon.co.uk/JINOU-OEM-Prog ... B07HQ9DJKG
by PiGraham
Fri Nov 08, 2019 11:19 am
Forum: Other projects
Topic: Wireless Distance Sensing?
Replies: 38
Views: 2226

Re: Wireless Distance Sensing?

But the new BT5.1 is supposed to do this. Nordic's nRF52811 is one of the first chips, but I have yet to see usable positioning solutions for hackers. This could change any month or week. That's exciting tech. Sub 1m accuracy with direction and elevation. https://www.youtube.com/watch?v=c3XqbEKmNcM
by PiGraham
Fri Nov 08, 2019 9:13 am
Forum: Other projects
Topic: Wireless Distance Sensing?
Replies: 38
Views: 2226

Re: Wireless Distance Sensing?

Not surprisingly there are a lot of phone apps claiming to "locate your Bluetooth devices" I tried a couple but they don't seem effective. The reported signal strength doesn't vary with distance in a consistent way. I used a Bluetooth speaker that was not connected. That means it keeps advertising i...
by PiGraham
Fri Nov 08, 2019 7:58 am
Forum: Automation, sensing and robotics
Topic: Distances of two different points in x y z coordinates
Replies: 23
Views: 1577

Re: Distances of two different points in x y z coordinates

You still haven't indicated what sort of accuracy you need for this measurement. That's critical.
The other key parameter is what distances you need to measure.

You can measure anything with triangulation, so long as you have at least one known distance.
by PiGraham
Thu Nov 07, 2019 5:51 pm
Forum: Troubleshooting
Topic: RPi Internal Pull-Up Resistors Not Functioning
Replies: 11
Views: 328

Re: RPi Internal Pull-Up Resistors Not Functioning

What do you see if you just poll the input and print the state and press the button?

Code: Select all

mport RPi.GPIO as GPIO
import os
import time

GPIO.setmode(GPIO.BCM)

GPIO.setup(21, GPIO.IN, pull_up_down=GPIO.PUD_UP)

while(True):
	print (GPIO.input(21))
	time.sleep(0.1)
	
by PiGraham
Thu Nov 07, 2019 3:12 pm
Forum: General discussion
Topic: GPIOs working in parallel
Replies: 5
Views: 394

Re: GPIOs working in parallel

Hello, Can I have different GPIOs working in parallel. For example can I have GPIO 17 -----> working as input GIPO 27 -----> working as input GPIO 22 -----> working as output at the same code? and nearly at the same time? You can certainly set au gpios as a mix of inputs and outputs. What do you me...
by PiGraham
Wed Nov 06, 2019 11:28 pm
Forum: General discussion
Topic: Use GPIO for PWM in "open collector mode" ?
Replies: 5
Views: 698

Re: Use GPIO for PWM in "open collector mode" ?

Thanks! Sounds good! So "open collector" is a term that refers to switching via (another) transistor? Not it means the collector of the output transistor is not tied to another transistor or a pullup to a voltage rail. That it is, the collector is free to float at any applied voltage when the trans...
by PiGraham
Wed Nov 06, 2019 5:54 pm
Forum: Automation, sensing and robotics
Topic: Distances of two different points in x y z coordinates
Replies: 23
Views: 1577

Re: Distances of two different points in x y z coordinates

Actually, its probably a reasonable assumption that the walls are vertical so a horizontal sweep of a distance sensor of any type could give you the walls and a range straight up could give the ceiling which gets you the corners. It all depends what accuracy is needed because walls aren't perfectly ...

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