Go to advanced search

by Paul Hutch
Fri Apr 20, 2018 3:24 pm
Forum: Advanced users
Topic: Powering multiple Pi Zero’s? (Again)
Replies: 23
Views: 3114

Re: Powering multiple Pi Zero’s? (Again)

Economics is why. What are the economics that make it prohibitive? I can't imagine any other solution that is cheaper than a couple rails to carry the current. Presumably it could actually be done with existing low voltage track lighting equipment, just with 5V instead of 10-24V. See the rest of my...
by Paul Hutch
Thu Apr 19, 2018 9:03 pm
Forum: Advanced users
Topic: Help with reading output from digital pressure sensor
Replies: 7
Views: 1199

Re: Help with reading output from digital pressure sensor

There is likely no way to get digital data, or a useful analog signal, out of the built-in pressure gauge, at least not without breaking the automatic inflation pressure feature. So think about adding an additional pressure sensor for the Pi to read and choose one that is Pi friendly.
by Paul Hutch
Thu Apr 19, 2018 8:58 pm
Forum: Advanced users
Topic: Powering multiple Pi Zero’s? (Again)
Replies: 23
Views: 3114

Re: Powering multiple Pi Zero’s? (Again)

I've got two words for you: Track Lighting My dream is to just have a rail that runs the length of my desk and from any point I can just attach the RPi (or similar USB device) I want to power. Some EE needs to explain why this kind of thing doesn't already exist. Economics is why. Not enough people...
by Paul Hutch
Thu Apr 19, 2018 8:26 pm
Forum: General discussion
Topic: Unpleasant new board smell ?
Replies: 68
Views: 12477

Re: Unpleasant new board smell ?

I recently opened a spare Pi3B I bought from Arrow Electronics in the USA last year when they had them discounted with free next day shipping. The G10/FR4 fiberglass PCB used on it is the variety that has a much more powerful fiberglass PCB smell than most G10/FR4 PCB's including the other Pi's I've...
by Paul Hutch
Thu Apr 19, 2018 7:09 pm
Forum: General discussion
Topic: Networking
Replies: 4
Views: 588

Re: Networking

I wish to network a number of Pi's together in such a manner that I can make use of the GPIO terminals e.g. an input into one Pi can be transmitted to a specified Pi or Pi's and initiate an output/s. It seems like what you want is more GPIO than a single RasPi can provide. If that is the case you s...
by Paul Hutch
Sat Apr 14, 2018 3:26 pm
Forum: General discussion
Topic: Heatsink required for Raspberry Pi 3 B+?
Replies: 59
Views: 64220

Re: Heatsink required for Raspberry Pi 3 B+?

A temperature of 50C/122F is generally accepted as too hot to touch That's no where near too hot to touch for me or anyone else I know IRL, I consume coffee and pizza at higher temperatures than that and have worked in attics for long periods at temperatures at and above that. I've measured and wor...
by Paul Hutch
Fri Apr 13, 2018 2:34 pm
Forum: General discussion
Topic: Heatsink required for Raspberry Pi 3 B+?
Replies: 59
Views: 64220

Re: Heatsink required for Raspberry Pi 3 B+?

Ok, so I have another RPI with not heat sinks, however in a case with a tiny little fan. rasp-no-heat-sink.png Just a few tasks , a couple of web sessions, live radio stream, one Skype session - temperature is bewten 30 - 40 C. Open a web session and watch video content - temp. jumps to 50. IIRC, C...
by Paul Hutch
Thu Apr 12, 2018 8:03 pm
Forum: General discussion
Topic: Heatsink required for Raspberry Pi 3 B+?
Replies: 59
Views: 64220

Re: Heatsink required for Raspberry Pi 3 B+?

Thanks for the clarification, is there an official link that would say heat sinks are not needed at all? https://www.raspberrypi.org/help/faqs/#performanceHeatsink You should not need to use a heatsink, as the chip used in the Raspberry Pi is equivalent to one used in a mobile phone, and should not...
by Paul Hutch
Wed Apr 11, 2018 6:11 pm
Forum: Advanced users
Topic: Multiple moisture sensors
Replies: 21
Views: 3623

Re: Multiple moisture sensors

Can you actually run multiples of that same sensor on the RPI and is there any sort of documentation or tutorials around on how to do it?? Yes, you can run as many of those sensors as you have inputs available, five is easy. Using up to thirteen of the sensors digital outputs would leave all the mu...
by Paul Hutch
Wed Apr 11, 2018 1:02 am
Forum: Advanced users
Topic: Multiple moisture sensors
Replies: 21
Views: 3623

Re: Multiple moisture sensors

Those sensors have two different outputs, analog and digital. The digital outputs can connect to GPIO pins and signal wet/dry. You just have to adjust the trimpots so that the digital outputs change at the wet/dry point you want. If you want to use the analog outputs to read a value for the moisture...
by Paul Hutch
Tue Apr 10, 2018 10:08 pm
Forum: Python
Topic: Infinite loop checking potentiometer
Replies: 40
Views: 4552

Re: Infinite loop checking potentiometer

Generally soldered connections, screw terminals, or tight gold connectors are required for long term reliable analog signals at high resolution. The key to knowing if that's what's needed is that when you exercise the connectors (disconnect/reconnect multiple times) the readings improve.
by Paul Hutch
Tue Apr 10, 2018 3:24 pm
Forum: Python
Topic: Raspberry Pi Light Detector
Replies: 35
Views: 12444

Re: Raspberry Pi Light Detector

A quick stylistic comment, all caps with underscores is usually reserved for constants, since you're changing the value of LED_BRIGHTNESS it is not a constant so should be lower case. Ref. https://www.python.org/dev/peps/pep-0008/#naming-conventions Of course as with everything in programming this i...
by Paul Hutch
Mon Apr 09, 2018 3:10 pm
Forum: Python
Topic: 100 % processing power
Replies: 15
Views: 1511

Re: 100 % processing power

You need a sleep in the "while True:" loops that will always execute on every pass through the loop to avoid 100% processor utilization. Your sleep statement are inside of conditional branches so will not always execute. I generally put it as the last statement in the loop because it makes a good vi...
by Paul Hutch
Mon Apr 09, 2018 2:58 pm
Forum: General discussion
Topic: Help with 4 channel relay (keyestudio)
Replies: 5
Views: 2784

Re: Help with 4 channel relay (keyestudio)

This is the best diagram I've found for converting WiringPi numbers to the BCM and hardware pin numbering schemes.
https://pinout.xyz/pinout/wiringpi
by Paul Hutch
Mon Apr 09, 2018 2:35 pm
Forum: General discussion
Topic: UART
Replies: 7
Views: 767

Re: UART

If you use a good old fashioned serial (modem) terminal programs on each side you can use their built-in file transfer capabilities. I've most often done this with Minicom on *nix and Tera Term on Windows. You start the file reception function on one side and then start the file send function on the...
by Paul Hutch
Mon Apr 09, 2018 2:27 pm
Forum: General discussion
Topic: SSH & FTP from particular WiFi not working
Replies: 3
Views: 415

Re: SSH & FTP from particular WiFi not working

The university WiFi may have a security configuration like my home guest network to stop CS majors from hacking other students devices. ;)

My guest network does not route between devices on the local network, communication is only allowed with devices outside of the local network.
by Paul Hutch
Sat Apr 07, 2018 12:58 am
Forum: Python
Topic: Pyserial ungraceful handling of disconnected USB serial adapter
Replies: 5
Views: 2185

Re: Pyserial ungraceful handling of disconnected USB serial adapter

I've never seen this happen but I may never have disconnected a USB serial adapter while it's in use. AFAIK pySerial uses the Windows API to communicate with COM ports so it seems more likely to be a Windows and/or USB driver issue. To make sure it's a pySerial only problem I'd see what happens if y...
by Paul Hutch
Fri Apr 06, 2018 11:51 pm
Forum: Beginners
Topic: How prevent screen going blank with raspian stretch?
Replies: 17
Views: 17450

Re: How prevent screen going blank with raspian stretch?

This week I got my two 3B's running Stretch with Desktop and my Raspberry Pi Desktop Virtual Machine all keeping the screen on. Install xscreensaver. For the VM I was able to install it from Preferences - > Add/Remove Software For the 3B's I had to use klricks command line instructions from above Re...
by Paul Hutch
Wed Mar 28, 2018 4:28 pm
Forum: General discussion
Topic: pi3: how to avoid "any" radiation?
Replies: 43
Views: 4548

Re: pi3: how to avoid "any" radiation?

Didnt want to start discussion about e-smog, but for example cell phone radiation has been proven to have negative effects on the human body That is false, cell phone radiation has been shown conclusively in thousands of tests over decades to not cause any harm to human beings (as physics predicted...
by Paul Hutch
Wed Mar 28, 2018 4:01 pm
Forum: Python
Topic: Is python too slow for my application?
Replies: 11
Views: 2313

Re: Is python too slow for my application?

https://www.youtube.com/watch?v=j4ibT3-1JFk He's gettin 10 ms latency with arduino. I can't get it with RPi at Ghz clocked processor. What a shame :roll: I have to stop here and take some rest... and play around with the actual setting. Without display :evil: From the video description, "makes a 12...
by Paul Hutch
Wed Mar 28, 2018 3:20 pm
Forum: Python
Topic: RPi CPU temp with Python
Replies: 15
Views: 29442

Re: RPi CPU temp with Python

IIRC, the Pi has a CPU temperature fail safe already built-in, it will slow the processor and eventually stop it if the temperature gets too high. Yes, the Pi is very robust. It wont actually stop, but in the extreme it will throttle down to 600Mhz. If it won't stop then DIY software CPU temperatur...
by Paul Hutch
Tue Mar 27, 2018 5:48 pm
Forum: Python
Topic: RPi CPU temp with Python
Replies: 15
Views: 29442

Re: RPi CPU temp with Python

I intend to place it in a greenhouse as a controller and would like to measure the temperature so it won't get too hot. I'm placing an external sensor as well. But knowing the CPU temp will help as a failsafe if the cooling system fails. IIRC, the Pi has a CPU temperature fail safe already built-in...
by Paul Hutch
Tue Mar 27, 2018 5:43 pm
Forum: Python
Topic: Is python too slow for my application?
Replies: 11
Views: 2313

Re: Is python too slow for my application?

SPI connected displays and the libraries to drive them typically have slow display update rates, make sure you are running the SPI bus as fast as it can go. Oh I get it Karrika! I should make a second thread running in parallel with the serial reading program. This means two separate ".py" files in ...
by Paul Hutch
Tue Mar 27, 2018 5:11 pm
Forum: Python
Topic: Is python too slow for my application?
Replies: 11
Views: 2313

Re: Is python too slow for my application?

If the purpose is to show the info on the desktop GUI screen then I'd switch to using one of the GUI frameworks, I prefer PyQt but many people prefer Tkinter. Having PIL draw a picture based on text and then display the picture is very slow compared to using the desktop GUI's built-in display capabi...
by Paul Hutch
Sat Mar 24, 2018 5:44 pm
Forum: General discussion
Topic: New PoE Hat
Replies: 32
Views: 9091

Re: New PoE Hat

fruitoftheloom wrote:
Sat Mar 24, 2018 5:18 pm
The specifications state 5V 2A :!:
I was replying to the Gigabit not working situation that I quoted. It had already been mentioned in post #3 that it is only 2A so if you need a full 2.5A for your application obviously it won't work.

Go to advanced search