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by Burngate
Sat Jul 21, 2018 10:16 am
Forum: General discussion
Topic: We're looking at introducing more swag - what would you like to see?
Replies: 46
Views: 833

Re: We're looking at introducing more swag - what would you like to see?

A Raspberry Pi Keyring for £6 Also known as a PiZero with a ring in a mounting hole. Can we have this suggestion in BOLD, ITALICS, UNDERLINED, CAPITALS and angels holding trumpets at either end? There's a guy somewhere on the forum asking if he should get his son a Pi for going to uni. He's going t...
by Burngate
Sat Jul 21, 2018 9:48 am
Forum: Troubleshooting
Topic: Raspberry pi Run pin wiring
Replies: 3
Views: 98

Re: Raspberry pi Run pin wiring

You don't need the pull-up resistor - one is already provided. I was going to point you towards the schematic, but can't for the life of me find it, for now. Nevertheless, when you do find it, towards the middle, R43, with the pin-header just below, and going into the chip on PG2 EDIT: https://www.r...
by Burngate
Fri Jul 20, 2018 5:56 pm
Forum: General discussion
Topic: Is it suitable? For a Computer Science course?
Replies: 12
Views: 341

Re: Is it suitable?

... Perhaps you should encourage other pursuits that he has already expressed serious interest in over the years. Rubbish. He's 18. He already knows about the other stuff, and he'll be with people his own age who also do that other stuff. If he's anything like I was, he'll discover he likes cooking...
by Burngate
Fri Jul 20, 2018 5:42 pm
Forum: Troubleshooting
Topic: Send Output to Composite/HDMI At Boot Time
Replies: 9
Views: 176

Re: Send Output to Composite/HDMI At Boot Time

I understood that pin 18 of the HDMI was fed with 5v just so the EDID info could be read even if the monitor was off, or hasn't yet finished booting.
Cutting that track (even if that's possible) might or might not do anything.
by Burngate
Fri Jul 20, 2018 5:28 pm
Forum: General discussion
Topic: We're looking at introducing more swag - what would you like to see?
Replies: 46
Views: 833

Re: We're looking at introducing more swag - what would you like to see?

I like that. There's a pi sticker on my luggage to help spot it on the conveyor belt when flying. A bit of a niche use case, but a tag like the one you linked would be nice. I need to be careful not to fly on the same plane as you; I'm using the same method to ID my bags! (I used to have a frozen c...
by Burngate
Fri Jul 20, 2018 9:59 am
Forum: General discussion
Topic: is it possible to connect six max6675 modules to a raspberry pi?
Replies: 1
Views: 43

Re: is it possible to connect six max6675 modules to a raspberry pi?

Since noone else has replied, I see no reason why not! For those (like me) who didn't recognise the number, MAX6675 is a Cold-Junction-Compensated K-Thermocouple-to-Digital Converter https://datasheets.maximintegrated.com/en/ds/MAX6675.pdf It works on SPI and uses SPI_SCLK (serial clock, pin 23) & S...
by Burngate
Thu Jul 19, 2018 5:37 pm
Forum: Beginners
Topic: raspberry clones
Replies: 24
Views: 751

Re: raspberry clones

Exchange rate just now according to Google (who are never wrong) is RS 89.94 = £1 So those prices are £35:58 (authorized reseller) & £32:24 (local shop) Perhaps he (and maybe some mates) get a deal on bulk-buying - RS or E14 save on packaging, someone to pack, a bloke in the finance department, some...
by Burngate
Thu Jul 19, 2018 8:57 am
Forum: Troubleshooting
Topic: Raspberry Pi Zero PW (indicators stop blinking and just glow)
Replies: 2
Views: 72

Re: Raspberry Pi Zero PW (indicators stop blinking and just glow)

You have a 3B+ that's working, so you have a fully functional SD card? What happens when you put that in your new Zero? Having put Noobs on your new card, what happens when you put that in your 3B+? You have already consulted https://www.raspberrypi.org/forums/viewtopic.php?f=28&t=58151 of course, s...
by Burngate
Wed Jul 18, 2018 5:42 pm
Forum: Troubleshooting
Topic: 'Extending' USB - not working
Replies: 7
Views: 203

Re: 'Extending' USB - not working

While both of those photos give V+ as 5.28V - slightly higher than I would have expected, but not excessive - in the second, 2.999V is suspiciously close to 3.0V even though the Pi uses 3.3V I'd be getting out my trusty meter and, with the Pi un-powered, measure the resistances between the data line...
by Burngate
Wed Jul 18, 2018 10:06 am
Forum: Beginners
Topic: RFID GPIOS
Replies: 2
Views: 58

Re: RFID GPIOS

Your first port of call has to be https://pinout.xyz/# Two things to note: (1) It runs on 3.3v, so it's safe to attach it to a Pi (lots of things run on 5v, so could damage your Pi if precautions aren't taken) (2) It uses SPI - MISO, MOSI, etc. so should be relatively easy to connect to a Pi Arduino...
by Burngate
Tue Jul 17, 2018 5:56 pm
Forum: General programming discussion
Topic: What Does Hiding the Details of I/O in Library Calls Teach?
Replies: 63
Views: 1403

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

Many years ago, I got taught a bit about computers & programming on an OU course using a teletype logged in to a remote mainframe. That taught me some of the fundamentals, but nothing about what went on inside a computer, nor how that mainframe handled multiple users. Getting and playing with a Wind...
by Burngate
Tue Jul 17, 2018 5:22 pm
Forum: Troubleshooting
Topic: Pi 3b+ not working a week after I added the iuniker dual fan
Replies: 2
Views: 133

Re: Pi 3b+ not working a week after I added the iuniker dual fan

I'm apparently the 85th viewer, and I also have no ideas, other than, since the original card works in a new Pi 3B+ but a freshly written card won't work in this Pi, it seems likely that it's a hardware problem. It may help to provide a link to "the new dual fan system from Iuniker" since I've no id...
by Burngate
Mon Jul 16, 2018 5:30 pm
Forum: Automation, sensing and robotics
Topic: Controlling homemade solenoids using Rpi Z W
Replies: 53
Views: 1074

Re: Controlling homemade solenoids using Rpi Z W

According to https://toshiba.semicon-storage.com/ap-en/product/linear/transistor-array/detail.ULN2003APG.html the datasheet for that particular part number ... Fixed that for you. It's noteworthy that Toshiba is EOLing that part, and recommending TBD62003. That uses a FET instead of a darlington, s...
by Burngate
Mon Jul 16, 2018 9:58 am
Forum: General discussion
Topic: New firmware for the official wireless dongle
Replies: 4
Views: 248

Re: New firmware for the official wireless dongle

Might be worth fixing those two links!
by Burngate
Mon Jul 16, 2018 9:28 am
Forum: Automation, sensing and robotics
Topic: Switching ON/OFF High Current Load
Replies: 13
Views: 411

Re: Switching ON/OFF High Current Load

As Z80 Refugee says, bipolar transistors are current-driven. The ratio of (current ito collector / current into base) is called Hfe, and is quoted on the data sheet for the particular device. However, as the collector-emitter voltage drops towards zero the Hfe also drops, so you need to put more cur...
by Burngate
Fri Jul 13, 2018 5:45 pm
Forum: Automation, sensing and robotics
Topic: Controlling homemade solenoids using Rpi Z W
Replies: 53
Views: 1074

Re: Controlling homemade solenoids using Rpi Z W

How about using miniature neodymium magnets as the cores? Now you've confused even me! according to earlier posts, the coil (300 turns round a non-ferrous (?) lollipop stick) pulls a pin (probably iron) down So using a magnet for the core would just hold the pin permanently down. I'd use a steel sc...
by Burngate
Fri Jul 13, 2018 5:25 pm
Forum: Add-ons
Topic: Can I switch one Pi off/on with another?
Replies: 13
Views: 333

Re: Can I switch one Pi off/on with another?

Actually, my idea was over the top - and not only that, but my hippocampus couldn't find the word "watchdog" - thanks, RaTTus Still, because the Pi isn't responding to anything, it may not be able to reset itself. So wire a 555 timer in resetable one-shot mode, and just keep resetting it. Once it's ...
by Burngate
Fri Jul 13, 2018 9:40 am
Forum: Add-ons
Topic: Can I switch one Pi off/on with another?
Replies: 13
Views: 333

Re: Can I switch one Pi off/on with another?

Maybe an over-the-top suggestion ... a Pi zero beside the 3B, on the same power supply (so the grounds are the same) and on the same network, with a GPIO connected to the 3B's RUN, and running a short script that queries the 3B. If it doesn't get a reply it briefly pulls its GPIO low ... Is it a 3B ...
by Burngate
Thu Jul 12, 2018 10:49 am
Forum: Troubleshooting
Topic: can't get AV video out properly on Pi3B
Replies: 12
Views: 248

Re: can't get AV video out properly on Pi3B

Bensimmo might be referring to https://www.raspberrypi.org/forums/viewtopic.php?f=28&t=58151 , an old favourite from way back when. though drgeoff's link is more apposite. If none of the above helps, perhaps you could take a photo of your monitor, upload it somewhere, and link to it so we can see fo...
by Burngate
Thu Jul 12, 2018 10:34 am
Forum: Automation, sensing and robotics
Topic: Two 6V motors through RPi3B
Replies: 19
Views: 514

Re: Two 6V motors through RPi3B

An obvious omission: where are your back-EMF protection diodes? See the diagrams in section 9.3.2, Figure 10 describes your particular usage. Without the diodes, you could destroy the L293D. The device in the picture is L293D which has the diodes in-built. No guarantee that the OP is using that rat...
by Burngate
Wed Jul 11, 2018 10:39 am
Forum: General discussion
Topic: Birthdays
Replies: 10
Views: 388

Re: Birthdays

This thread having caught my eye, I thought I'd have a quick squiz at the members list. There are, apparently, 237548 members, so at 25 members per page, that's 9502 pages. Sorting by number of posts, on the first 42 pages are members with 100 or more posts. Page 90 takes us to 50 posts, and page 19...
by Burngate
Tue Jul 10, 2018 6:15 pm
Forum: Troubleshooting
Topic: Problem with GPIO pins
Replies: 28
Views: 570

Re: Problem with GPIO pins

Hmm. I did rather let myself in for that one, didn't I? I've got a spreadsheet with all the GPIOs, what they're called and what they do on the various Pi's, but it's a bit out of date at the moment (every time I get close, they bring out another Pi. Tell them we DON'T need Pi 4!) Give me half an hou...
by Burngate
Tue Jul 10, 2018 6:05 pm
Forum: Troubleshooting
Topic: Problem with GPIO pins
Replies: 28
Views: 570

Re: Problem with GPIO pins

Bloody pictorials! I read (and understand) circuit diagrams. I'm with him on that! I'm not a C-coder, so I could be wrong ... In your Python code you've selected GPIO.setmode(GPIO.BOARD) But in your C code you've said #include <wiringPi.h> Now, in Python at any rate, GPIO.BOARD means the physical p...
by Burngate
Mon Jun 18, 2018 6:07 pm
Forum: Troubleshooting
Topic: keyboard configuration problem?
Replies: 9
Views: 291

Re: keyboard configuration problem?

Where I come from, braces hold my trousers up, while brackets hold my shelves up. But that's off-topic. What's also off-topic but would also be interesting: given a British pound is an L (again for Libre) where did the two horizontal lines come from? And why is a dollar sign an S, and where did the ...
by Burngate
Wed Jun 13, 2018 10:19 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Circuit using a MOSFET to control power
Replies: 7
Views: 527

Re: Circuit using a MOSFET to control power

That's my understanding, as well. What's drawn is a source follower, a.k.a common drain. Wikipedia has a page. So, as illustrated, an enhancement FET will only turn on while the gate voltage is higher than the output, limiting the maximum output voltage at 3.3V It's even worse than that - the gate-s...

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