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by Burngate
Sat Oct 05, 2019 9:56 am
Forum: Off topic discussion
Topic: I wanna unsolder display conector RASPBERRY PI 4
Replies: 11
Views: 1076

Re: I wanna unsolder display conector RASPBERRY PI 4

Can I ask why you want to do this?
by Burngate
Sat Oct 05, 2019 9:47 am
Forum: Off topic discussion
Topic: I wanna unsolder display conector RASPBERRY PI 4
Replies: 11
Views: 1076

Re: I wanna unsolder display conector RASPBERRY PI 4

It's just a connector - the Pi doesn't depend on the bits of plastic or metal to work.
So it depends on how good your soldering skills are.
by Burngate
Fri Oct 04, 2019 10:55 am
Forum: Graphics, sound and multimedia
Topic: Interference Problems
Replies: 3
Views: 289

Re: Interference Problems

I'd be looking for a ground loop - I assume the negative side of the 19v supply is connected to the ground of the amp and (via the 5v voltage converter) to the ground of the Pi, and the ground of the audio jack is also connected to the ground of the amp.
by Burngate
Fri Oct 04, 2019 10:03 am
Forum: Off topic discussion
Topic: I need to rotate a heavy mass in a controlled manner - Do I need ramps?
Replies: 5
Views: 903

Re: I need to rotate a heavy mass in a controlled manner - Do I need ramps?

I have a mass of 1,5 kg with its center of mass 15 cm away from the rotations center. That gives me 2,55 Nm. That doesn't make a lot of sense, to me, so maybe there's something you're not telling us. Just as, in a linear system, force / mass gives acceleration, so in a rotating system, torque, mome...
by Burngate
Mon Sep 30, 2019 6:16 pm
Forum: Media centres
Topic: Resister value for summing circuit?
Replies: 1
Views: 250

Re: Resister value for summing circuit?

A lot depends on the input impedance of your amplifier, but ... The Pi's audio circuitry is such that it shouldn't be too stressed even if it's fed into a short-circuit, so you may find just joining the two channels together works satisfactorily, albeit the upper frequency limit may be compromised. ...
by Burngate
Sat Sep 28, 2019 6:12 pm
Forum: Beginners
Topic: 230/240 motor/fan Engine
Replies: 1
Views: 84

Re: 230/240 motor/fan Engine

How are you powering your Pi? It's very possible that the current surge as the motor starts is disturbing the Pi's supply. What relay PCB? There isn't a standard one. And it's possible that, if you're using the Pi's 5v to power the relay's coil, the current in that is disturbing the Pi. What is a "s...
by Burngate
Sat Sep 28, 2019 9:04 am
Forum: Troubleshooting
Topic: My Pi 4 Forces 4K When Desired Output is 1080p
Replies: 7
Views: 295

Re: My Pi 4 Forces 4K When Desired Output is 1080p

Could it be a problem with the settings in your TV?
Some TV manufacturers have strange ideas about what their customers want to see on their screens!
by Burngate
Sat Sep 28, 2019 8:54 am
Forum: Bare metal, Assembly language
Topic: Setting the output register for a GPIO on Pi 4
Replies: 21
Views: 1090

Re: Setting the output register for a GPIO on Pi 4

Having read LdB's reply to your question, and realised I'd misread your question (I too can't tell the difference between 10 and 36) I came downstairs this morning ready to delete my reply as totally irrelevant. However, since you've quoted me, I'll leave it there, as a lesson for others: read the q...
by Burngate
Fri Sep 27, 2019 5:20 pm
Forum: Bare metal, Assembly language
Topic: Setting the output register for a GPIO on Pi 4
Replies: 21
Views: 1090

Re: Setting the output register for a GPIO on Pi 4

Once upon a time ... when the first Pi was being designed, on the chip they wanted to use they had a range of GPIOs (General Purpose Input/Outputs) that they wanted to bring out to a header. Inside the chip, the registers that accessed them had them in a certain order. This gave rise to the GPIO num...
by Burngate
Fri Sep 27, 2019 10:01 am
Forum: Bare metal, Assembly language
Topic: Setting the output register for a GPIO on Pi 4
Replies: 21
Views: 1090

Re: Setting the output register for a GPIO on Pi 4

nickell8448 wrote:
Fri Sep 27, 2019 9:54 am
To understand this well, you state that GPIO16 is pin 10 on the 40 pin header, how did you make that connection? I could not make that connection based on all the reading I have done. Do you any specific resource you would recommend to learn this?
https://pinout.xyz/#
by Burngate
Fri Sep 27, 2019 9:32 am
Forum: Beginners
Topic: NOOBS won't install.
Replies: 3
Views: 118

Re: NOOBS won't install.

... also my Mac at home has no sd card slot Buy a USB SD card reader? It could save hours of frustration treking to and from school! It would allow you to check that the card has been written correctly. It's not unknown for internal SD card readers to not work correctly, and that might apply to you...
by Burngate
Fri Sep 27, 2019 9:26 am
Forum: Troubleshooting
Topic: Raspberry pins not working
Replies: 7
Views: 288

Re: Raspberry pins not working

As Imperf3ct says, the 5v pins are connected directly to the power input, so must be at 5v for the Pi to be working. So, two questions: What are you using as a ground reference for the (black) lead of your meter? A good place is the metal shroud of any of the USB or HDMI sockets. Is the battery in y...
by Burngate
Mon Sep 23, 2019 5:57 pm
Forum: Advanced users
Topic: CORRECT RESISTOR FOR 5V LED ARRAY
Replies: 7
Views: 239

Re: Correct resistor for 5V LED array

Oh - and don't use all capitals in the title - it looks like shouting.
You can change that yourself, by editing your first post.
by Burngate
Mon Sep 23, 2019 5:54 pm
Forum: Advanced users
Topic: CORRECT RESISTOR FOR 5V LED ARRAY
Replies: 7
Views: 239

Re: CORRECT RESISTOR FOR 5V LED ARRAY

Regarding R5, it needs to be low enough in value to allow enough current into the base of the transistor to saturate it (turn it on fully) but not more than the GPIO can handle. The GPIO cannot provide more than 16mA, and it would be better to keep it below a couple of mA or so. So, given that the G...
by Burngate
Mon Sep 23, 2019 10:40 am
Forum: Troubleshooting
Topic: Raspberry Pi 4 boot troubleshooting
Replies: 1
Views: 77

Re: Raspberry Pi 4 boot troubleshooting

Your power LED going out means you do have a power supply problem.
The fact that it only goes out when the Pi starts to boot means the supply is just good enough when the Pi isn't doing anything.

https://www.raspberrypi.org/forums/view ... 28&t=58151
by Burngate
Mon Sep 23, 2019 9:53 am
Forum: General discussion
Topic: Back Voltage from USB Hub
Replies: 19
Views: 724

Re: Back Voltage from USB Hub

R-Pi B Rev. 1.0 had a 140mA polyfuse feeding each USB socket from the 5v rail after the input polyfuse. R-Pi B Rev. 2.0 & 2.1 had the USB sockets fed directly from the 5v rail after the input polyfuse. For each of these, back-powering is possible. Also, this generation is recognisable by having only...
by Burngate
Fri Sep 20, 2019 10:47 am
Forum: Graphics, sound and multimedia
Topic: Soldering a speaker straight to the Raspberry Pi
Replies: 12
Views: 474

Re: Soldering a speaker straight to the Raspberry Pi

.... I'm only looking to output something around 8 ohms? Something the size of a us quarter or slightly bigger. 8Ω (ohms) isn't a useful measure of what a speaker can do - it's only its impedance, and can mean anything from the speaker inside a 1960's Tranny to what's inside those banks of boxes on...
by Burngate
Thu Sep 19, 2019 10:28 am
Forum: Troubleshooting
Topic: Exit button on Raspberry PI
Replies: 3
Views: 164

Re: Exit button on Raspberry PI

Hi, I am trying to figure out how to wire a door exit button to my Pi Access system and I do know the code to utilise the GPIOs to activate the switch. Not sure what you mean - a switch is an input device. It doesn't need "activating" - it just works 1) Will it matter if my push exit button says 10...
by Burngate
Thu Sep 19, 2019 10:13 am
Forum: Python
Topic: Send data through a single GPIO pin
Replies: 3
Views: 151

Re: Send data through a single GPIO pin

According to the date-stamps, Scotty101 appears to live within 11 million miles of Sunningdale.
Unless he is also a Tralfamadorian.
by Burngate
Thu Sep 19, 2019 9:02 am
Forum: Troubleshooting
Topic: Strange callback behaviour with GPIO.BOTH - RPi3
Replies: 7
Views: 171

Re: Strange callback behaviour with GPIO.BOTH - RPi3

I'm not going to comment on the software side (though I'd be inclined to add a chunk at the start of mycallback to check that newstatus really is different from what it used to be). But the internal pull-ups are about 50k, which isn't very strong, depending on lengths of wires, etc. You could add yo...
by Burngate
Thu Sep 19, 2019 8:26 am
Forum: Python
Topic: Send data through a single GPIO pin
Replies: 3
Views: 151

Re: Send data through a single GPIO pin

https://en.wikipedia.org/wiki/Universal ... ransmitter
The Pi has two GPIOs - pins 8 & 10, BCM 14 & 15 - that can be dedicated to TXD & RXD for exactly that function.

Actually two pins are required on each Pi - TXD & ground on one Pi, RXD & ground on the other.
by Burngate
Thu Sep 12, 2019 10:06 am
Forum: General discussion
Topic: Back Voltage from USB Hub
Replies: 19
Views: 724

Re: Back Voltage from USB Hub

The B+ had a AP2553 acting as a reverse-current blocking device. Apparently the 4B does not. One of the dangers is that two power supplies, as you have here, with slightly different voltages can fight each other, with unknown consequences. Would it be possible to open the hub and cut the 5v trace to...
by Burngate
Wed Sep 11, 2019 5:00 pm
Forum: General discussion
Topic: RPI 4 USB-C supply
Replies: 37
Views: 1630

Re: RPI 4 USB-C supply

Don't, whatever you do, argue with Jamesh.
He's an engineer, he's a moderator, but more to the point, he's all-powerful

If you argue, he makes life difficult for the rest of us
by Burngate
Wed Sep 11, 2019 4:51 pm
Forum: Beginners
Topic: Relay - can it be used in reverse (signal microcontroller) ?
Replies: 14
Views: 675

Re: Relay - can it be used in reverse (signal microcontroller) ?

ElEscalador wrote:
Wed Sep 11, 2019 12:25 pm
You could certainly use a relay with a 100vac coil like this one https://amzn.to/2NVr0RV
Unless you're in Britain, or Europe, or other places with 230V AC

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