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by PiGraham
Mon Feb 19, 2018 3:19 pm
Forum: Python
Topic: Infinite loop malfunction
Replies: 15
Views: 243

Re: Infinite loop malfunction

Thanks for looking in. That's what i'm thinking too. Because i ran a quick test with a button and got the same problem. when the button is pressed, the mqtt payload delivers once but the sound plays multiple times. And that is the reason why i posted my client code for anyone to spot the cause of t...
by PiGraham
Mon Feb 19, 2018 1:44 pm
Forum: Python
Topic: Infinite loop malfunction
Replies: 15
Views: 243

Re: Infinite loop malfunction

Actually, 'the other side' side is an LDR that spits out its readings every millisecond and when ever a set threshold is exceeded it publishes to the mqtt topic. I noticed that if I kept my palm over the LDR for too long that it publishes to the topic as long as my palm is over the LDR. So yes. It ...
by PiGraham
Mon Feb 19, 2018 12:57 pm
Forum: Python
Topic: Infinite loop malfunction
Replies: 15
Views: 243

Re: Infinite loop malfunction

Actually, 'the other side' side is an LDR that spits out its readings every millisecond and when ever a set threshold is exceeded it publishes to the mqtt topic. I noticed that if I kept my palm over the LDR for too long that it publishes to the topic as long as my palm is over the LDR. So yes. It ...
by PiGraham
Mon Feb 19, 2018 12:10 pm
Forum: Beginners
Topic: Distance sensor that penetrates glass
Replies: 25
Views: 671

Re: Distance sensor that penetrates glass

The big question is what's this for? If it's a secondary driver aid to make drivers aware of bad habits it might be OK. If it's an important safety system this is entirely the wrong way to go about it. Don't use a Pi and don't have a $60 budget.
by PiGraham
Mon Feb 19, 2018 12:05 pm
Forum: Beginners
Topic: Distance sensor that penetrates glass
Replies: 25
Views: 671

Re: Distance sensor that penetrates glass

For the cost of a web cam or Pi Camera it should be possible to do whatever iOnRoad does to do the ranging. You can get speed from ODBII using a $12.59 interface . So speed and distance is possible within budget. What you have to do is find out if it's good enough for whatever you have for it. Ultra...
by PiGraham
Mon Feb 19, 2018 9:23 am
Forum: General discussion
Topic: How do I calculate servo current draws
Replies: 5
Views: 155

Re: How do I calculate servo current draws

Ah yes, you wrote "when still" which in the context of a servo will be a light load maintaining a position rather than accelerating a load. So to measure a maximum current drive the servo against an end stop (or otherwise fix the shaft and try to move the position) and measure the current. That will...
by PiGraham
Mon Feb 19, 2018 9:01 am
Forum: Automation, sensing and robotics
Topic: Long Range wifi for a moving vehicle
Replies: 6
Views: 148

Re: Long Range wifi for a moving vehicle

brucepi wrote:
Mon Feb 19, 2018 1:22 am
so since it is mobile it seems that I have to use GSM instead of wifi?
This is for a telemetry system. the vehicle is in a competition and must send data to the station.
What range do you need?
If it's a race circuit you have different options than if it's a long rally stage.
by PiGraham
Mon Feb 19, 2018 8:58 am
Forum: General discussion
Topic: How do I calculate servo current draws
Replies: 5
Views: 155

Re: How do I calculate servo current draws

Also the peak current while moving will be higher than steady current while still and will depend on how fast you try to move the servo. You will probably need an oscilloscope of some form to catch the transient current pulse as they will be too short (100s of mS maybe) to see on a meter. PeterO St...
by PiGraham
Sun Feb 18, 2018 9:08 pm
Forum: Automation, sensing and robotics
Topic: Long Range wifi for a moving vehicle
Replies: 6
Views: 148

Re: Long Range wifi for a moving vehicle

The usual way to connect data with a vehicle is to use GSM (for slow / small data) or 4G/LTE (mobile broadband for fast / big data) You can get in-car 4G to WiFi devices that take a SIM and enable any Wi-Fi device to connect to internet on the move. As with phones you have a choice of discounted dev...
by PiGraham
Sun Feb 18, 2018 6:32 pm
Forum: Wanted
Topic: If this is feasible - then I am going to need help
Replies: 6
Views: 113

Re: If this is feasible - then I am going to need help

Sun Feb 18, 2018 11:56 am But I'm curious. What USP do you think a Pi based device would have compared to Chromecast, Firestick, Smart TV's with the feature built in or any number of Android "TV sticks"? ............ Maybe I am missing the main point to begin with. I have been assuming the Pi set u...
by PiGraham
Sun Feb 18, 2018 6:06 pm
Forum: Graphics, sound and multimedia
Topic: pi player piano
Replies: 9
Views: 288

Re: pi player piano

You can also play notes in Scratch.
http://foxbotindustries.com/build-easy-floor-piano/
by PiGraham
Sun Feb 18, 2018 5:56 pm
Forum: Wanted
Topic: If this is feasible - then I am going to need help
Replies: 6
Views: 113

Re: If this is feasible - then I am going to need help

But I'm curious. What USP do you think a Pi based device would have compared to Chromecast, Firestick, Smart TV's with the feature built in or any number of Android "TV sticks"?
by PiGraham
Sun Feb 18, 2018 5:54 pm
Forum: Wanted
Topic: If this is feasible - then I am going to need help
Replies: 6
Views: 113

Re: If this is feasible - then I am going to need help

Sun Feb 18, 2018 11:41 am What do you want to 'cast' to where? Surely you need an internet connection to do it. ............ From a smart phone to a HD TV. As I understand it, the pi, using raspicast mirrors to the TV/RPi via SSH - no internet required. If someone does not have a "net" connection, ...
by PiGraham
Fri Feb 16, 2018 1:28 pm
Forum: Beginners
Topic: Distance sensor that penetrates glass
Replies: 25
Views: 671

Re: Distance sensor that penetrates glass

To sum up, there is no low cost option for measuring the distance between cars from inside the vehicle, right? No. There was this, which is cheap if you already have the phone, and demonstrates that it's possible to do well enough (not defined) with a single forward facing camera. Have a look on go...
by PiGraham
Fri Feb 16, 2018 8:04 am
Forum: Beginners
Topic: Replacing Arduino nanos with Raspi
Replies: 3
Views: 167

Re: Replacing Arduino nanos with Raspi

Hello, I am currently trying to replace a system run by Arduino nano to Raspberry pi. The individual systems are a with pump and an agitator. The pump and the agitator are individually connected to nanos and the nanos are connected to an Arduino UNO. The D0 to D7 pins on both the nanos are used and...
by PiGraham
Thu Feb 15, 2018 7:41 pm
Forum: Graphics, sound and multimedia
Topic: pi player piano
Replies: 9
Views: 288

Re: pi player piano

A printer mechanism feeding fanfold paper covered in dots under a row of photo sensors with blinking lights has some appeal, don't you think? With paper feed running it would even look like a player piano with paper naturally forming a cylindrical shape. You haven't said anything about plans for how...
by PiGraham
Thu Feb 15, 2018 7:33 pm
Forum: Networking and servers
Topic: Access Raspberry Pi without vpn or port forwarding
Replies: 10
Views: 318

Re: Access Raspberry Pi without vpn or port forwarding

How do you mean? I install VNC on the raspberry pi and on my webserver i call the raspberry pi using ssh? All my customers have multiple raspberry pi's so i need to address all of them individually. Will this be possible? Thanks If you setup the Pi to 'phone home', connecting to you publically acce...
by PiGraham
Thu Feb 15, 2018 3:58 pm
Forum: Networking and servers
Topic: Access Raspberry Pi without vpn or port forwarding
Replies: 10
Views: 318

Re: Access Raspberry Pi without vpn or port forwarding

How about reverse SSH and reverse VNC?
Make an outbound connection and receive commands back from the remote 'client'
by PiGraham
Thu Feb 15, 2018 3:37 pm
Forum: Troubleshooting
Topic: Epson Scanner...
Replies: 7
Views: 171

Re: Epson Scanner...

Maybe the source code is available. Maybe it can be built for Arm. Maybe it's not worth the effort.
by PiGraham
Thu Feb 15, 2018 3:14 pm
Forum: Troubleshooting
Topic: Epson Scanner...
Replies: 7
Views: 171

Re: Epson Scanner...

Just wondering, has anyone been successful in getting an Epson scanner (in my case a V500) to work with their Pi? From what I was reading, the drivers from Epson don't work with ARM processors, correct? Is there any workaround for this, or is this just not feasible? Epsom Perfection V500 Photo unsu...
by PiGraham
Thu Feb 15, 2018 2:30 pm
Forum: Python
Topic: Timer Interrupt with Python 3
Replies: 4
Views: 154

Re: Timer Interrupt with Python 3

I am not familiar with the code but a quick read suggested to me that the callback or interrupt function would have to restart the timer if you want it to be periodic, otherwise it will fire once and stop. But that is just my interpretation. Your variable a is actually two variables in different sco...
by PiGraham
Thu Feb 15, 2018 12:57 pm
Forum: Graphics, sound and multimedia
Topic: pi player piano
Replies: 9
Views: 288

Re: pi player piano

Are you teaching music or technology? How will the students make the holes? How will the punched sheets be fed? I fear that doing it by hand will distract from the musical aspects. A card punch that can make regular holes in registered positions would help a lot but that's a significant project in i...
by PiGraham
Wed Feb 14, 2018 3:28 pm
Forum: General discussion
Topic: Can I desolder the micro USB port in the pi zero and replace with usb c
Replies: 10
Views: 310

Re: Can I desolder the micro USB port in the pi zero and replace with usb c

Easiest solution is to use an plug adapter. https://www.amazon.com/Fheaven-Adapter-Connector-Connect-Samsung/dp/B01N5Q90XB/ That would be easiest, by far. The existence of the adaptor demonstrates that soundness of the basic concept. If you can make a connector wired as the adaptor it should work a...
by PiGraham
Wed Feb 14, 2018 3:26 pm
Forum: General discussion
Topic: Can I desolder the micro USB port in the pi zero and replace with usb c
Replies: 10
Views: 310

Re: Can I desolder the micro USB port in the pi zero and replace with usb c

Without the extra connections, the OP would lose the ability to plug in his cable without regard to orientation...a major selling point of USB-C. So while it may be physically possible to make the change, it is in some ways counterproductive. Orientation independence is achieved simply by placement...

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