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by PiGraham
Sat Aug 18, 2018 5:06 pm
Forum: Camera board
Topic: Picamera with custom lens, color issue
Replies: 7
Views: 251

Re: Picamera with custom lens, color issue

The other strange thing is that, if we use the picamera without lens (so only the sensor), this circle color issue also exists on the pictures. What do you think about this? I think that is to be expected. The lens introduces a circular shading pattern. The correction for that will be an inverse ci...
by PiGraham
Thu Aug 16, 2018 9:32 pm
Forum: Automation, sensing and robotics
Topic: How to read motor's tach out open collector
Replies: 14
Views: 359

Re: How to read motor's tach out open collector

My bad. It turns out the readings were correct. I wasn't actually getting full speed as I though. I am controlling the motor using PWM and when I set it to 100% it not really a full speed. I found it out when I controlled it with potentiometer then setting to max it just goes like crazy and I got 2...
by PiGraham
Thu Aug 16, 2018 6:48 pm
Forum: Automation, sensing and robotics
Topic: How to read motor's tach out open collector
Replies: 14
Views: 359

Re: How to read motor's tach out open collector

Can you turn the rotor one turn by and see what the tach signal does?

How do you know it's running at 2580? Do you have a separate way to measure it?
by PiGraham
Wed Aug 15, 2018 10:05 pm
Forum: Troubleshooting
Topic: Interrupt Button Only Firing ~10% Of Presses
Replies: 12
Views: 197

Re: Interrupt Button Only Firing ~10% Of Presses

kraligor wrote:
Tue Aug 14, 2018 3:49 pm

Oh, and yes, I've tried different buttons of the same model.

Any suggestions?

Try different gpio pins, just in case there is a configuration issue or hardware problem with that pin.

Check the config of BCM 26 with

Code: Select all

gpio readall
by PiGraham
Wed Aug 15, 2018 2:58 pm
Forum: Automation, sensing and robotics
Topic: Motor/Driver Recommendation for balancing robot
Replies: 2
Views: 87

Re: Motor/Driver Recommendation for balancing robot

Direct drive probably helps. Geared motors can have problems with backlash.
Her's an example using steppers.

https://www.robotshop.com/letsmakerobot ... sing-robot.
I've seen a few projects like this run a microcontroller to do the balancing.
by PiGraham
Wed Aug 15, 2018 2:45 pm
Forum: Troubleshooting
Topic: Interrupt Button Only Firing ~10% Of Presses
Replies: 12
Views: 197

Re: Interrupt Button Only Firing ~10% Of Presses

You say only firing ~10% of presses but you don't say how fast you are pressing it. If you press it once every second or two does it miss?
What happens if you remove the debounce?
by PiGraham
Wed Aug 15, 2018 8:22 am
Forum: Camera board
Topic: PiCam detection
Replies: 7
Views: 321

Re: PiCam detection

Hello guys, I have a project using PiCam to observe the conveyor in our plant because sometime it was stucked.Is it possible to use PiCam to detect when the conveyor is stucked and stop ? I researched many projects on google but there are only Picam motion detect security system.How about detect "m...
by PiGraham
Wed Aug 15, 2018 8:15 am
Forum: Camera board
Topic: PiCam detection
Replies: 7
Views: 321

Re: PiCam detection

It's doable but you would be far better off (ie. cheaper and more robust solution) getting a dedicated industrial belt motion sensor and tie that into your PLC controlling the belt drive. I agree, this is a much better solution. Any industrial sensor that is triggered by motion of the belt can be u...
by PiGraham
Tue Aug 14, 2018 2:07 pm
Forum: Graphics, sound and multimedia
Topic: Fancy GPS overlay on video
Replies: 4
Views: 165

Re: Fancy GPS overlay on video

Many of the overlays you'll see look like speedometers, and also a small tracking overlay that shows the track of the boat as it goes around the course. Can you draw an example graphic? Is it like this example for Sony action cam? https://www.youtube.com/watch?v=wbPyKHwFuTI Looks like what you need...
by PiGraham
Tue Aug 14, 2018 9:27 am
Forum: Troubleshooting
Topic: Data capture via GPIO
Replies: 7
Views: 166

Re: Data capture via GPIO

How many channels do you intend to use at what sample rate, for how long? What do you intend to do with the data? at 8 channels and 110kHz that's 2.64 Mbytes/s which may be possible but I think you would have to sample asynchronously and find the sync pulses in the data. You might also need to de-se...
by PiGraham
Mon Aug 13, 2018 8:15 am
Forum: Beginners
Topic: How to detect an old style wired doorbell only - nothing else
Replies: 20
Views: 396

Re: How to detect an old style wired doorbell only - nothing else

Did you know that you are providing approximately - 0.8V to the input of your ESP8266 ;) . Instead of this: A resistor / zener diode clips this so a 0 - 3.3V 50 Hz pulse is fed into a GPIO pin. However, I find you code interesting and I need to take a closer look at it. Yes. That is true. It was lo...
by PiGraham
Sat Aug 11, 2018 10:40 pm
Forum: Automation, sensing and robotics
Topic: How to read motor's tach out open collector
Replies: 14
Views: 359

Re: How to read motor's tach out open collector

Connect Pin 4 tacho to a gpio input, connect the GND pin between motor interface and Pi and set a pullup. Set a callback on the input to cout up each time the tach line pulses low.
by PiGraham
Sat Aug 11, 2018 8:41 am
Forum: Beginners
Topic: How to detect an old style wired doorbell only - nothing else
Replies: 20
Views: 396

Re: How to detect an old style wired doorbell only - nothing else

Useful circuits Brandon92.
It isn't essential to rectify ac or filter 50/100Hz since it is possible to handle a pulse train in software. So you could leave out D1 to D4 and C3 and C2.
The opto will turn on every other half cycle and if there are any no pulses in 20ms the bell is not pressed.
by PiGraham
Fri Aug 10, 2018 6:49 pm
Forum: Beginners
Topic: How to detect an old style wired doorbell only - nothing else
Replies: 20
Views: 396

Re: How to detect an old style wired doorbell only - nothing else

rpdom wrote:
Fri Aug 10, 2018 5:43 pm
The reason for the opto is to filter out any interference that the long leads may pick up. The opto-isolator is a lot less sensitive than a GPIO.
It will also protect the Pi from any high voltage spikes that can be produced by electromagnetic bells.

Sounds like a nice setup you have there.
by PiGraham
Fri Aug 10, 2018 3:18 pm
Forum: Beginners
Topic: How to detect an old style wired doorbell only - nothing else
Replies: 20
Views: 396

Re: How to detect an old style wired doorbell only - nothing else

https://electrical.knoji.com/images/user/danmsnyder/doorbell-transformer-wiring-fbdaee2c.jpg Is the transformer could be ac or dc. Can you check? Basically you can connect and opto-isolator across the bell terminals and connect the output to a gpio. Connect it like a push button. Choose a series re...
by PiGraham
Wed Aug 08, 2018 2:02 pm
Forum: Advanced users
Topic: How to sense my smartphone in a room
Replies: 5
Views: 196

Re: How to sense my smartphone in a room

If you keep Bluetooth or WiFi on you can detect if your phone is in range of another device. If you have admin access to a WiFi rounter in your room you could check the DHCP list on the router for your phone. Check the RSSI levels on two or more radios to locate the phone. If you pair a Pi3B+ with t...
by PiGraham
Wed Aug 08, 2018 9:44 am
Forum: Camera board
Topic: Picamera with custom lens, color issue
Replies: 7
Views: 251

Re: Picamera with custom lens, color issue

Corrections are applied for the standard lens. The issues are discussed here:
viewtopic.php?t=168777

You can get the raw pixel values and apply your own Bayer processing and colour corrections for still images.
by PiGraham
Mon Aug 06, 2018 6:14 pm
Forum: Python
Topic: I need help with an LDR
Replies: 11
Views: 286

Re: I need help with an LDR

I'm not convinced about the logic behind the opening and especially the closing of the door. Sounds much too easy to have a situation in which the door closes when the car is not fully clear of the doorway. Excellent point. At least two sensors are required. One to detect approach and one to detect...
by PiGraham
Mon Aug 06, 2018 4:39 pm
Forum: Python
Topic: I need help with an LDR
Replies: 11
Views: 286

Re: I need help with an LDR

You can use an LDR for this sort of thing but an alternative might be better. I suggest you do not rely on daylight to illuminate the LDR because that can vary a lot. Use an LED light to shine a beam across the space where the car will go. You can have a solution that is less sensitive to daylight v...
by PiGraham
Mon Aug 06, 2018 4:26 pm
Forum: Beginners
Topic: using PI with 2 serail ports?
Replies: 3
Views: 71

Re: using PI with 2 serail ports?

USB serial interfaces are cheap and effective to I'd go that way, but DMA controlled software serial on any gpio pin is another option.

viewtopic.php?t=35544#p446164

http://abyz.me.uk/rpi/pigpio/cif.html#gpioWaveAddSerial
by PiGraham
Mon Aug 06, 2018 7:05 am
Forum: Beginners
Topic: Will sharing keyboard & mouse between Pi and PC require Pi reboot?
Replies: 6
Views: 176

Re: Will sharing keyboard & mouse between Pi and PC require Pi reboot?

You might find it more convenient to use VNC or SSH to view the Pi desktop or SSH to use the command line from your PC without changing connections.

Plugging and unplugging USB devices doesn't require a reboot though, so you can do that if you prefer.
by PiGraham
Sun Aug 05, 2018 3:56 pm
Forum: General discussion
Topic: Tranquility Project
Replies: 61
Views: 1894

Re: Tranquility Project

Seems that it would be easier to hitchhike a ride to the ISS and send it on its way from there. The problem then being getting there, the entry, Getting a tiny experiment module delivered to the ISS is worlds away from getting a launch system deployed from the ISS. Your enthusiasm is commendable bu...
by PiGraham
Sun Aug 05, 2018 3:52 pm
Forum: Troubleshooting
Topic: MOSFET switch is leaking current when off
Replies: 15
Views: 365

Re: MOSFET switch is leaking current when off

Why do people seeking help so often refuse to provide basic information or try simple tests?
A neat diagram is a good thing, but much better to show the actual circuit in a photo. Then we aren't confounded by getting the diagram wrong (100k /10k) we see what you actually used.
Help us to help you.
by PiGraham
Sat Aug 04, 2018 3:37 pm
Forum: Troubleshooting
Topic: MOSFET switch is leaking current when off
Replies: 15
Views: 365

Re: MOSFET switch is leaking current when off

It might help to see exactly the circuit connections and code being used.
by PiGraham
Fri Aug 03, 2018 8:57 am
Forum: General discussion
Topic: GPIO as GND
Replies: 47
Views: 807

Re: GPIO as GND

@PiGraham My point was more the use of the pi. If he want to make in total 50 units. I think it is a overkill way to use a pi to control only 4 Leds. And the cost are indeed not the leds itself. It may be that the Pi is doing something much more involved than just lighting LEDs. The OP gives no clu...

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