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by Z80 Refugee
Tue Jul 17, 2018 11:41 pm
Forum: General programming discussion
Topic: What Does Hiding the Details of I/O in Library Calls Teach?
Replies: 19
Views: 324

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

Ok, memory mapping and address translation complicates things, but that aside: what makes the RPi I/O any worse than any other memory mapped hardware accessed with a bit of bitblitting? A library call to do the address mapping and maybe some initialisation would paper over the variability between RP...
by Z80 Refugee
Tue Jul 17, 2018 11:30 pm
Forum: General discussion
Topic: Free Fall detection through Accelerometer using raspberry pi
Replies: 9
Views: 209

Re: Free Fall detection through Accelerometer using raspberry pi

Centrifugal force is the apparent effect of a centripetal acceleration. An accelerometer would measure the acceleration, not a force.
by Z80 Refugee
Tue Jul 17, 2018 11:19 pm
Forum: Automation, sensing and robotics
Topic: connecting multiple magnetic switches
Replies: 25
Views: 2247

Re: connecting multiple magnetic switches

Not getting it to an argument over this as I have said before we are not in an industrial or military environment here , this is a hobby environment were people will use what works and is often simple to build. As for my experience work for BT for over 40 years as a power maintenance technician ins...
by Z80 Refugee
Tue Jul 17, 2018 11:00 pm
Forum: General programming discussion
Topic: What Does Hiding the Details of I/O in Library Calls Teach?
Replies: 19
Views: 324

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

Heater wrote:
Tue Jul 17, 2018 7:26 pm
That is ambiguous. Did they swap out your defective hardware or the defective software engineer?
I can make a light flash without any help from software. The only light software can flash without help from hardware is a simulation of one.
by Z80 Refugee
Tue Jul 17, 2018 4:59 pm
Forum: General programming discussion
Topic: What Does Hiding the Details of I/O in Library Calls Teach?
Replies: 19
Views: 324

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

I'm completely happy with all those comments... if the programming were confined to a self-contained unit. As soon as it's not, you end up with the situation I was faced with: somebody who thinks they're a whizz kid programmer but has no knowledge of the fundamentals. Yes, no problem with libraries ...
by Z80 Refugee
Tue Jul 17, 2018 1:43 pm
Forum: General programming discussion
Topic: What Does Hiding the Details of I/O in Library Calls Teach?
Replies: 19
Views: 324

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

The RPi is a teaching resource for programming, right? Physical computing is a good model for teaching programming, because it rewards by making things happen (lights flash, motors move, whatever), right? What bothers me is that these student programmers really don't get to know anything about what ...
by Z80 Refugee
Tue Jul 17, 2018 12:22 pm
Forum: Automation, sensing and robotics
Topic: Is it possible to read the value of a UK dimmer switch with Raspberry Pi?
Replies: 21
Views: 349

Re: Is it possible to read the value of a UK dimmer switch with Raspberry Pi?

drgeoff wrote:
Tue Jul 17, 2018 10:57 am
The standard pot shaft (not just in the UK) is 1/4 inch diameter with a locating flat for the grub screw or spring bar of the knob.
...which is 6.35mm.
by Z80 Refugee
Tue Jul 17, 2018 9:23 am
Forum: Automation, sensing and robotics
Topic: Is it possible to read the value of a UK dimmer switch with Raspberry Pi?
Replies: 21
Views: 349

Re: Is it possible to read the value of a UK dimmer switch with Raspberry Pi?

I now know after some research that the UK has some strange habits/tastes when it comes to light switches - we use a different circuit design (no earth), different sized fixings, and prefer different dimmer designs from everyone else! I've seen threads with people asking for Z-Wave dimmer switches ...
by Z80 Refugee
Tue Jul 17, 2018 8:28 am
Forum: Automation, sensing and robotics
Topic: Is it possible to read the value of a UK dimmer switch with Raspberry Pi?
Replies: 21
Views: 349

Re: Is it possible to read the value of a UK dimmer switch with Raspberry Pi?

So you are basically looking for a rotary potentiometer or encoder that has the shaft as a push button to turn on. Something like this https://news.thomasnet.com/fullstory/potentiometer-switch-offers-rotary-and-push-on-functionality-20006470 You would still need a way to convert the analogue potent...
by Z80 Refugee
Tue Jul 17, 2018 6:37 am
Forum: General discussion
Topic: Controlling 100 LEDs?
Replies: 12
Views: 341

Re: Controlling 100 LEDs?

Basically I want to be able to control about 16 or more electromagnets. To be able to turn them off and on from my PC. Each one is fairly small (dice sized) and doesn't require much current, although I will use an external power supply. The first thing you need to know is how much current and how m...
by Z80 Refugee
Mon Jul 16, 2018 10:03 pm
Forum: Beginners
Topic: Controlling Pi over Long Distances
Replies: 6
Views: 123

Re: Controlling Pi over Long Distances

It's Internet or nothing - any use of radio spectrum for this will require extensive licencing. A two-way link over those distances is possible, but you would need to buy in a properly type-approved radio link and licence its use. The licence-free bands put strict limits on transmitter power (theref...
by Z80 Refugee
Mon Jul 16, 2018 9:49 pm
Forum: General discussion
Topic: Controlling 100 LEDs?
Replies: 12
Views: 341

Re: Controlling 100 LEDs?

Just out of curiosity what's the max number of pins I can extend to even with additional products? The RPi is great for programming. It's great for getting some logic signals in and out. It is not great at interfacing to real-world hardware, and was never designed to be. That's why we have HATs. HA...
by Z80 Refugee
Mon Jul 16, 2018 9:40 pm
Forum: Troubleshooting
Topic: Pi 3B+ / Shorting 3.3V to GND
Replies: 14
Views: 288

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

Indeed. A fuse is there to stop the wiring catching fire in the event of a short.
by Z80 Refugee
Mon Jul 16, 2018 9:34 pm
Forum: Automation, sensing and robotics
Topic: Controlling homemade solenoids using Rpi Z W
Replies: 53
Views: 845

Re: Controlling homemade solenoids using Rpi Z W

dibolero wrote:
Mon Jul 16, 2018 1:14 pm
I'm not sure if this a problem with the type of component we bought or a problem with the circuit diagram we're following.
Why not follow the circuit diagram I've given you, or the circuits in my hardware interfacing article?
by Z80 Refugee
Mon Jul 16, 2018 9:30 pm
Forum: Automation, sensing and robotics
Topic: Is it possible to read the value of a UK dimmer switch with Raspberry Pi?
Replies: 21
Views: 349

Re: Is it possible to read the value of a UK dimmer switch with Raspberry Pi?

I simply want to use a standard dimmer as a rotary encoder and on/off switch. Won't work (not without an inordinate amount of effort, and it doesn't sound like you have the experience). Inside the dimmer switch is a potentiometer and a push-on push-off switch. These are inputs to some electronics w...
by Z80 Refugee
Mon Jul 16, 2018 8:45 am
Forum: Automation, sensing and robotics
Topic: Is it possible to read the value of a UK dimmer switch with Raspberry Pi?
Replies: 21
Views: 349

Re: Is it possible to read the value of a UK dimmer switch with Raspberry Pi?

piglet wrote:
Mon Jul 16, 2018 8:34 am
Sounds to me like the OP is asking whether a dimmer switch can be used as/like a rotary encoder; not necessarily anything to do with mains voltages (I sure hope)
If that's the case, the answer is no. But the item linked is not a dimmer switch.
by Z80 Refugee
Mon Jul 16, 2018 8:35 am
Forum: Automation, sensing and robotics
Topic: Switching ON/OFF High Current Load
Replies: 13
Views: 328

Re: Switching ON/OFF High Current Load

Transistor switching vs MOSFETs, what is the key difference if any? I am new to circuitry aspects such as these. Transistors are current driven. To gate 75A you would need to provide a base current in the scale of amps. I don't think I have ever seen a 75A transistor. Power electronics uses MOSFETs...
by Z80 Refugee
Sun Jul 15, 2018 10:38 pm
Forum: Automation, sensing and robotics
Topic: Is it possible to read the value of a UK dimmer switch with Raspberry Pi?
Replies: 21
Views: 349

Re: Is it possible to read the value of a UK dimmer switch with Raspberry Pi?

I don't understand what you are asking. The link you have provided is to a two-way push-on push-off switch with no dimmer function, just made to fit in a bank with other modules that may include dimmer switches. Are you asking if you can modify it to include some kind of rotational information, when...
by Z80 Refugee
Sun Jul 15, 2018 10:31 pm
Forum: Automation, sensing and robotics
Topic: Switching ON/OFF High Current Load
Replies: 13
Views: 328

Re: Switching ON/OFF High Current Load

nuggetchris wrote:
Sun Jul 15, 2018 6:14 pm
If I were to run each magnet simultaneous at half current I would be accepting half force from the magnets.
Are you sure about that? Two magnets each contributing half the normal force, when either one of them can do the job on its own...
by Z80 Refugee
Sun Jul 15, 2018 10:25 pm
Forum: Automation, sensing and robotics
Topic: connecting multiple magnetic switches
Replies: 25
Views: 2247

Re: connecting multiple magnetic switches

So I am suggesting you use 1 resistor and 1 pot for each circuit and I clearly stated you need to set up the voltage output form the potential divider circuit before connecting to the gpio. Do you really want to cloud the education I am trying to provide by arguing your case? Do you have 40+ years ...
by Z80 Refugee
Sun Jul 15, 2018 4:45 pm
Forum: General discussion
Topic: What is a good site to get working roms from?
Replies: 3
Views: 179

Re: What is a good site to get working rooms from?

How about getting the title right, so we know you are talking about ROMs (note capitals) without having to open the thread?
by Z80 Refugee
Sun Jul 15, 2018 4:40 pm
Forum: Add-ons
Topic: Relay' connected to Rpi Zero W - causes it to freeze
Replies: 29
Views: 547

Re: Relay' connected to Rpi Zero W - causes it to freeze

1. I use common relays that operate at 5VDC, and triggered by gpio 3.3V. I do not think that labeling it as "Arduino" or "Raspberry Pi" does not make any technical difference. It absolutely does, as several of us have said many times over. For some reason people see a 5V pin on the GPIO and assume ...
by Z80 Refugee
Sun Jul 15, 2018 10:16 am
Forum: Troubleshooting
Topic: Crashing RPi when doing "heavy" stuff
Replies: 13
Views: 367

Re: Crashing RPi when doing "heavy" stuff

Nobody has mentioned the possibility that the workload is causing the PSU to glitch.
by Z80 Refugee
Sun Jul 15, 2018 10:13 am
Forum: Add-ons
Topic: Hardware Specification of the RPi's
Replies: 22
Views: 468

Re: Hardware Specification of the RPi's

I don't think there's anything special about the RPi which would make it any different from typical electronics assemblies: as long as the humidity does not condense on the board, it should be OK. That said, I am lead to understand the Compute Module version has full testing/specifications (I have n...
by Z80 Refugee
Sun Jul 15, 2018 10:04 am
Forum: Automation, sensing and robotics
Topic: connecting multiple magnetic switches
Replies: 25
Views: 2247

Re: connecting multiple magnetic switches

if you are going to be using switch on cable runs that long I would suggest you use 5v and an adjustable potential divider circuit for each of your switches, I did it this way on a similar project I did using a pi and had no trouble with voltage drop or false triggering. This is crazy. There is abs...

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