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by PiGraham
Mon Feb 12, 2018 9:55 am
Forum: General discussion
Topic: Image Processing
Replies: 4
Views: 221

Re: Image Processing

You can use two USB webcams simultaneously, or a Pi camera and a USB camera. Or you can use many USB cameras sequentially. Another thong you can do is use a curved mirror to view all around the mango from one camera. If you can roll the fruit past a single camera you can see the whole thing in a seq...
by PiGraham
Mon Feb 12, 2018 9:44 am
Forum: Automation, sensing and robotics
Topic: Detect heat of stovetop?
Replies: 9
Views: 237

Re: Detect heat of stovetop?

There are various ways to measure temperature without the sensing device getting hot. A thermal camera https://learn.adafruit.com/adafruit-amg8833-8x8-thermal-camera-sensor/raspberry-pi-thermal-camera An Infrared Thermometer https://www.amazon.co.uk/Thermometer-Tacklife-58℉-716℉-Temperature-Conserva...
by PiGraham
Mon Feb 12, 2018 9:16 am
Forum: Advanced users
Topic: Raspberry Image comparison - fog detection
Replies: 7
Views: 329

Re: Raspberry Image comparison - fog detection

About the Sobel instead I'm still not sure on how to get a simple "number" from all of that. You could do it the same way, just applied to filtered image rather than the original image. A Sobel filter emphasises edges or high contrast in a small neighbourhood. Fog reduces contrast so the Sobel valu...
by PiGraham
Sun Feb 11, 2018 5:57 pm
Forum: Camera board
Topic: University Project- Please help
Replies: 9
Views: 367

Re: University Project- Please help

There are also internet SMS gateways

You may be able to use push notifications.
by PiGraham
Sun Feb 11, 2018 9:56 am
Forum: General discussion
Topic: IP Doorbell camera ?
Replies: 8
Views: 356

Re: IP Doorbell camera ?

I think it will be much easier to do what you want if you use a Pi for each device because you they are open and you can configure them to suit. A Pi B+ could be a good choice for the door mounted unit since it is the cheapest Pi with Ethernet and has USB ports if you want to add two-way audio. Pi Z...
by PiGraham
Sat Feb 10, 2018 2:36 pm
Forum: Beginners
Topic: PiCamera right next to (magnetic) speaker?
Replies: 2
Views: 120

Re: PiCamera right next to (magnetic) speaker?

Vibrations from the speaker could possibly blur the image or even cause the lens to move out of focus. I think you will have to try it to find out.
by PiGraham
Sat Feb 10, 2018 12:03 pm
Forum: Camera board
Topic: University Project- Please help
Replies: 9
Views: 367

Re: University Project- Please help

On a broader point, how does a video recording benefit anyone's safety? I can see the message and two way video contact could be helpful but video recording on the device seems only useful for after the fact reporting. If someone is wearing such a device I'd put fall detection and location in there ...
by PiGraham
Sat Feb 10, 2018 11:59 am
Forum: Camera board
Topic: University Project- Please help
Replies: 9
Views: 367

Re: University Project- Please help

It seems essential that Pi can boot to video recording in a second or two at most. The Pi will have to be powered down most of the time to gat any useful battery life. I take it this is a standby device. Take a look at Ultibo which I believe boots super-fast and can support the camera and SD storage...
by PiGraham
Sat Feb 10, 2018 11:51 am
Forum: General discussion
Topic: IP Doorbell camera ?
Replies: 8
Views: 356

Re: IP Doorbell camera ?

This IP doorbell is scarily iunsecure, but hackable...

http://www.qdh.org.uk/wordpress/2016/02 ... -doorbell/

Maybe the same works for the KONX.


What is the plan? To make a commercial doorbell talk to a Pi like it talks to a smartphone?
by PiGraham
Fri Feb 09, 2018 9:29 pm
Forum: Beginners
Topic: Reading a specific voltage/current
Replies: 10
Views: 304

Re: Reading a specific voltage/current

Thank you PiGraham The difference between is that instead of a button I have a 5 or 12 volt input. Ridles? Do you mean you want to tell if a signal is at 5V or at 12V? Or is it between no volts and anything between 5 and 12V? Or are there two signals, one 0 or 5V and the other 0 or 12V? You can sca...
by PiGraham
Fri Feb 09, 2018 3:57 pm
Forum: Advanced users
Topic: Raspberry Image comparison - fog detection
Replies: 7
Views: 329

Re: Raspberry Image comparison - fog detection

Just two untested ideas. 1. Compare the standard deviation of pixel values from fog and no-fog images. Are they significantly different? Probably not necessary to use all the pixels. 2. Run an edge detector over the images. Sum the absolute values. Significant difference between fog and no fog? I t...
by PiGraham
Fri Feb 09, 2018 8:24 am
Forum: General discussion
Topic: IP Doorbell camera ?
Replies: 8
Views: 356

Re: IP Doorbell camera ?

Did you see this?
https://www.raspberrypi.org/blog/internet-doorbell/

Google finds lots of this type of project.
by PiGraham
Thu Feb 08, 2018 3:30 pm
Forum: Automation, sensing and robotics
Topic: Automatic watering system for multiple plants with Rpi 3
Replies: 8
Views: 385

Re: Automatic watering system for multiple plants with Rpi 3

I think that's the right track. You can put some logic in the ESP so watering isn't dependent on mains power or Wi-Fi. Pi / MQTT is ideal to monitor the system overall to make sure no plant is starved of water, detect leaks, alert if an ESP fails, keep batteries fresh. etc More on low power from CNL...
by PiGraham
Thu Feb 08, 2018 9:38 am
Forum: Beginners
Topic: I'm new, have ideas, recommendations to shorten the learning curve
Replies: 3
Views: 208

Re: I'm new, have ideas, recommendations to shorten the learning curve

I want to make a 3D camera... What do you mean by 3d camera? Do you mean a camera that measures depth and can produce 3D models: The two main methods are structured light - like a Kinect / Structure sensor / RealSense and photogrammetry that works out shapes by matching points between multiple imag...
by PiGraham
Wed Feb 07, 2018 11:03 pm
Forum: Other projects
Topic: Cheap touchscreen display
Replies: 12
Views: 622

Re: Cheap touchscreen display

OP is looking for a touchscreen. OP is looking for the moon. Can't have it all. (or, if we can I'll have a nice new Ferrari with all running costs included for £100 ) For $25 there's a choice between a tiny low-res SPI screen with resistive touch, or a large screen with high res but no touch.
by PiGraham
Wed Feb 07, 2018 11:01 pm
Forum: Other projects
Topic: Cheap touchscreen display
Replies: 12
Views: 622

Re: Cheap touchscreen display

Imperf3kt wrote:
Wed Feb 07, 2018 10:39 pm
OP is looking for a touchscreen.
OP is looking for the moon. Can't have it all. For $25 there's a choice between a tiny low-res SPI screen with resistive touch, or a large screen with high res but no touch.
by PiGraham
Wed Feb 07, 2018 10:02 pm
Forum: Automation, sensing and robotics
Topic: What's the lightest, reliable external pull-up I can use?
Replies: 14
Views: 646

Re: What's the lightest, reliable external pull-up I can use?

Just read back a bit. I don't have 3.3V in my box. I have 5.2V and one more R for a divider is easy and small. The pullup is for the input on the Pi and the Pi has 3.3V And the STAT output is a constant current sink so the voltage on the input will be 3.3 V max and 3.3 - 10-uA x Rpullup when STAT i...
by PiGraham
Wed Feb 07, 2018 9:48 pm
Forum: Other projects
Topic: Cheap touchscreen display
Replies: 12
Views: 622

Re: Cheap touchscreen display

Example

Acer V173 DO bmd 17" LCD Monitor / CCTV with VGA & DVI Connections

Image

£15.00

https://www.ebay.co.uk/itm/Acer-V173-DO ... SwefVZnL~N
by PiGraham
Wed Feb 07, 2018 7:44 pm
Forum: Automation, sensing and robotics
Topic: What's the lightest, reliable external pull-up I can use?
Replies: 14
Views: 646

Re: What's the lightest, reliable external pull-up I can use?

Why do you have a divider at all? If you pull up to 3.3V you don't need it.

CMOS input typical impedance is 10^12 ohms, certainly much higher than the device datasheet 470k suggested pullup.
by PiGraham
Wed Feb 07, 2018 4:47 pm
Forum: Advanced users
Topic: Under-voltage event logging?
Replies: 3
Views: 264

Re: Under-voltage event logging?

I think vcgencmd get_throttled only shows that it happened at least once. I don't know, but I guess Dom does: If the power drops below the voltage threshold are brief (e.g. a few milliseconds) then you won't spot it on the LED. But get_throttled has some persistence (matching the visible warning sy...
by PiGraham
Wed Feb 07, 2018 4:27 pm
Forum: Other projects
Topic: Cheap touchscreen display
Replies: 12
Views: 622

Re: Cheap touchscreen display

Guys do you unterstand cheap? I am from Romania. I mean max 25$ dollars. Im a kid and im saving money.. I am not poor, but in Romania its pretty much 60$ or etc... You didn't suggest a price, so you got suggestions for displays that matched what you did ask for. You could get larger screens cheaper...
by PiGraham
Wed Feb 07, 2018 4:20 pm
Forum: Beginners
Topic: Apache2, How can another device connect to RPI?
Replies: 4
Views: 163

Re: Apache2, How can another device connect to RPI?

Does other device has to be something like wire connected to RPI? Both devices must be connected to the same network (or separate networks that are bridged to allow port 80 connections). If you connect your Pi to your home broadband router and can access the internet from it, and you connect your p...
by PiGraham
Wed Feb 07, 2018 4:12 pm
Forum: General discussion
Topic: [CANCELLED] building a pi zero in a smartphone
Replies: 9
Views: 330

Re: building a pi zero in a smartphone

As I read the OP the intent is not to make a PiZero into a phone but to use a phone as a case and peripherals for a portable Pi. But all the peripherals in the phone are suited specifically to the phone, not to a Pi. It makes more sense to start with peripherals that do work with the PiZero and fit ...
by PiGraham
Wed Feb 07, 2018 3:32 pm
Forum: General discussion
Topic: [SOLVED} Pi zero analog video output
Replies: 13
Views: 532

Re: Pi zero video output

Another pi is not an option since i want to make something like this https://www.youtube.com/watch?v=j5dXx0NhLxg but than RCA instead of HDMI but if it needs all those extra modules it wont fit anyway so... do you have any suggestions how it would still be possible? otherwise I will just give it up...

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