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by hippy
Wed Jul 18, 2018 9:08 pm
Forum: Troubleshooting
Topic: 'Extending' USB - not working
Replies: 5
Views: 143

Re: 'Extending' USB - not working

in the second, 2.999V is suspiciously close to 3.0V even though the Pi uses 3.3V And, interestingly enough, a quick search for USB electrical specs shows a differential "1" transmitted as D+ > 2V8, D- < 0V3 which is what we seem to have. Also what does the USB measuring device do ? It could be the ...
by hippy
Wed Jul 18, 2018 5:19 pm
Forum: Troubleshooting
Topic: 'Extending' USB - not working
Replies: 5
Views: 143

Re: 'Extending' USB - not working

Looks to me you have a wiring error somewhere or possibly a short which is pulling D+ towards 3V3. I suppose it could be something about the wiring which is causing the USB to communicate which is actually pushing the D+ voltage higher as an average. I can't recall exactly what the electrons do on t...
by hippy
Wed Jul 18, 2018 4:57 pm
Forum: General programming discussion
Topic: What Does Hiding the Details of I/O in Library Calls Teach?
Replies: 37
Views: 641

Re: What Does Hiding the Details of I/O in Library Calls Teach?

Of course the second one chooses Python to tackle a problem one has given up all hope of small size and performance. Exactly that. I have no idea how much of anything my code is using. I have gone down the 'don't and won't care until I hit a problem' path like many others before me, and then I'll b...
by hippy
Wed Jul 18, 2018 2:49 pm
Forum: General programming discussion
Topic: What Does Hiding the Details of I/O in Library Calls Teach?
Replies: 37
Views: 641

Re: What Does Hiding the Details of I/O in Library Calls Teach?

The problem I have with libraries is it often leads to a lot of bloat. Encouraging people to use libraries without thought is probably why we often have such huge executables these days. People just include libraries to do what they want and don't care or worry what else that drags in which they may...
by hippy
Wed Jul 18, 2018 2:12 pm
Forum: General discussion
Topic: "Low depth" power supply
Replies: 15
Views: 404

Re: "Low depth" power supply

The simple version is: no appliance is allowed to be connected to a household power circuit unless it has been approved by the SAA and installed by a qualified and licensed electrician. From a quick Googling on what can be done in Australia; the rules do seem to be far more proscriptive than in the...
by hippy
Wed Jul 18, 2018 12:38 pm
Forum: The MagPi
Topic: STICKY: Errata
Replies: 52
Views: 23279

Re: STICKY: Errata

Issue 71, Page 75, line 35 of listing, wind_speed.py -

print( calculate_speed(wind_interval), "cm/h")

Should be "cm/s".
by hippy
Wed Jul 18, 2018 10:07 am
Forum: General discussion
Topic: "Low depth" power supply
Replies: 15
Views: 404

Re: "Low depth" power supply

Imperf3kt wrote:
Wed Jul 18, 2018 8:41 am
Everyone here who made custom jobs, has probably voided any insurance they have, and would also likely be arrested if caught, even if they are a licensed electrician.
I believe the phrase required is "citation needed".
by hippy
Wed Jul 18, 2018 9:58 am
Forum: General programming discussion
Topic: What Does Hiding the Details of I/O in Library Calls Teach?
Replies: 37
Views: 641

Re: What Does Hiding the Details of I/O in Library Calls Teach?

I have a gut feeling that if the RPi is trying to take the mystery out of how computers are made to do things, there is still a big mystery in how they are made to do (physical) things... Is there not a significant population who are just picking up the RPi as a hobby, unguided by anyone? How will ...
by hippy
Tue Jul 17, 2018 7:07 pm
Forum: General discussion
Topic: "Low depth" power supply
Replies: 15
Views: 404

Re: "Low depth" power supply

eludlow wrote:
Tue Jul 17, 2018 4:18 pm
Does anyone know if a "slim" power supply supply is available?
I created one by cutting a mains PSU apart, extracting the PCB, soldering mains lead to come out one end, with 5V out the other. That was then secured in a slim plastic case.
by hippy
Tue Jul 17, 2018 5:48 pm
Forum: General programming discussion
Topic: What Does Hiding the Details of I/O in Library Calls Teach?
Replies: 37
Views: 641

Re: What Does Hiding the Details of I/O in Library Calls Teach?

Yes, no problem with libraries etc etc, but at some point (not too late on) expose them to actually controlling a GPIO pin raw so they know what's in a library call. Why though? I see the important thing being to provide people with the means of achieving what they want to achieve and if they want ...
by hippy
Mon Jul 16, 2018 6:38 pm
Forum: Automation, sensing and robotics
Topic: Detect where Pi is physically docked
Replies: 9
Views: 203

Re: Detect where Pi is physically docked

laagland wrote:
Mon Jul 16, 2018 6:17 pm
This will work perfectly, thanks! :)
Any chance of saying which "this" it is which you have chosen ?
by hippy
Mon Jul 16, 2018 4:30 pm
Forum: Automation, sensing and robotics
Topic: Detect where Pi is physically docked
Replies: 9
Views: 203

Re: Detect where Pi is physically docked

Also, more than 2 docks should be possible. If you need to identify one of a number of docks you can extend the third pin open / short to 0V solution to each dock having a different resistor in each. You can measure the resistance, using a voltage divider and ADC or the time taken to discharge a ca...
by hippy
Mon Jul 16, 2018 4:15 pm
Forum: Automation, sensing and robotics
Topic: Detect where Pi is physically docked
Replies: 9
Views: 203

Re: Detect where Pi is physically docked

You could create special power cables at each location which can identify themselves. This is interesting, how would that work? One solution would be to provide power to your Pi via a 3 or more pin connector, XLR, DIN or anything similar. One pin 0V, one pin 5V, another pin left open circuit for on...
by hippy
Mon Jul 16, 2018 4:06 pm
Forum: Other projects
Topic: "Airbag" Case
Replies: 3
Views: 120

Re: "Airbag" Case

You can run rubber tubing or foam pipe lagging around the edge of a Pi PCB or even mount it inside a rubberised phone case. Simplest solution is probably to sandwich it between two lumps of polystyrene with elastic bands. I am not sure of the need to protect a Pi board. If it had an LCD fitted it wo...
by hippy
Mon Jul 16, 2018 3:49 pm
Forum: Python
Topic: Tkinter + socket programming
Replies: 11
Views: 400

Re: Tkinter + socket programming

You don't need to launch the Tkinter root.mainloop() as a separate thread, can just invoke it as you did originally.
by hippy
Mon Jul 16, 2018 3:20 pm
Forum: Beginners
Topic: Can I using wi-fi connect two pi's together without a hotspot?
Replies: 13
Views: 251

Re: Can I using wi-fi connect two pi's together without a hotspot?

lets forget that we are using the Wi-Fi "layer" and think of only using TCP/IP by itself. I am sure that using the basic TCP/IP routines one can communicate between Is without a router. Correct. For a wired network; just connect one device's RJ45 to the other device's RJ45. They can both communicat...
by hippy
Mon Jul 16, 2018 3:07 pm
Forum: Automation, sensing and robotics
Topic: Detect where Pi is physically docked
Replies: 9
Views: 203

Re: Detect where Pi is physically docked

If connected to something that could be used to reveal what it is connected to as suggested. A trace route might help if there's an internet connection. You could just add a switch. Though, for an automatic determination, perhaps a compass chip or something could be used if it is reliably oriented d...
by hippy
Mon Jul 16, 2018 1:05 pm
Forum: Add-ons
Topic: Hardware Specification of the RPi's
Replies: 22
Views: 486

Re: Hardware Specification of the RPi's

bonzadog wrote:
Mon Jul 16, 2018 9:47 am
Well, the question has been answered: No Spec from RPi but some by other people.
I don't believe that is the case at all. Perhaps you could detail a necessary specification which has not been officially provided ?
by hippy
Mon Jul 16, 2018 12:55 pm
Forum: Beginners
Topic: Can I using wi-fi connect two pi's together without a hotspot?
Replies: 13
Views: 251

Re: Can I using wi-fi connect two pi's together without a hotspot?

Thanks for the unfortunate info but as an old retired engineer, I want to know why UI need an access point. Setting up the communication medium and what that handles are two separate things. WiFi requires one thing to be a master and the rest to be slaves. That master will normally be a router or a...
by hippy
Mon Jul 16, 2018 11:42 am
Forum: Beginners
Topic: How to restore rewritten version of CSV file?
Replies: 11
Views: 248

Re: How to restore rewritten version of CSV file?

Embarrassingly overwriting old data with new and losing the previous data is something everyone will probably do at some point. Two techniques to avoid that are - Create every file with a unique file name, often using a time stamp, adjusted or with some extra sequencing number to ensure there are no...
by hippy
Sun Jul 15, 2018 5:17 pm
Forum: Other projects
Topic: Question about safe shutdown
Replies: 2
Views: 70

Re: Question about safe shutdown

Added: Sorry; misread that as "without breadboard".

Solder your wires direct to the switch and other components ?

Some additional context to your question may help provide more appropriate responses.[/i]
by hippy
Sun Jul 15, 2018 5:13 pm
Forum: Troubleshooting
Topic: File attachments
Replies: 6
Views: 106

Re: File attachments

I just tried to attach a .txt. file to a reply and it was rejected. What is the best way to include text file data in a reply?.....RDK If it's not too large you could include it in-line wrapped in [ code ] ... [ /code ] tags which will preserve its spacing. If it is too large it might be worth aski...
by hippy
Sun Jul 15, 2018 2:07 pm
Forum: Troubleshooting
Topic: Pi 3B+ / Shorting 3.3V to GND
Replies: 14
Views: 294

Re: Pi 3B+ / Shorting 3.3V to GND

There is a chip (U8, a XR77004) on the 3B+ which contains most of the circuitry for some DC-DC converters. I was about to say the same. I would have expected that to include short-circuit, over-current and thermal shutdown protections which would contain the failure and avoid the polyfuse 'blowing'...
by hippy
Sat Jul 14, 2018 12:37 pm
Forum: Add-ons
Topic: Hardware Specification of the RPi's
Replies: 22
Views: 486

Re: Hardware Specification of the RPi's

I have some technical literature about the RPi's but nothing that is of real meaning. Jamesh is currently creating / compiling / collating a single Technical FAQ but I believe nearly all the technical information you are seeking is already documented and publicly available, albeit spread around a l...
by hippy
Fri Jul 13, 2018 1:20 pm
Forum: Off topic discussion
Topic: Connecting leads to a button/coin battery
Replies: 5
Views: 230

Re: Connecting leads to a button/coin battery

Clothes peg? Wrap a wire around each of the two ends. Clamp the cell between them. You can add drawing pins pushed into both sides of the jaws to get a good contact. Just file away any lacquer on them if there is any. Solder the wire to the drawing pin spike. Another alternative is to put the butto...

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