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by davidcoton
Sun Jul 12, 2020 9:22 pm
Forum: Beginners
Topic: Over-Voltage and Over-Current protection circuit
Replies: 10
Views: 343

Re: Over-Voltage and Over-Current protection circuit

every conceivable attack. i am just after electrical protection to save the raspberry pi from damage and to save my house from fire. Contradiction? Moving goalposts? What do you really want, the impossible or just something slightly useful in limited circumstances? To save us all getting it wrong a...
by davidcoton
Sun Jul 12, 2020 1:37 pm
Forum: General discussion
Topic: Raspberry Pi clustering.
Replies: 6
Views: 243

Re: Raspberry Pi clustering.

B.Goode wrote:
Sun Jul 12, 2020 8:58 am
The Raspberry Pi Foundation does not sell hardware to individual customers.
But Raspberry Pi Trading operate a retail shop in Cambridge.... :idea: :ugeek: 8-) :D
by davidcoton
Sun Jul 12, 2020 1:19 pm
Forum: General discussion
Topic: Overclocking the Pi 4B 8GB to 2.35 GHz
Replies: 6
Views: 403

Re: Overclocking the Pi 4B 8GB to 2.35 GHz

The power supply limitation is not on the external 5V supply (though of course that needs to be adequate). It's one of the lower voltage rails that runs out of oomph.
by davidcoton
Sat Jul 11, 2020 2:33 pm
Forum: Beginners
Topic: Help in Building a new OS for car infotainment system
Replies: 5
Views: 126

Re: Help in Building a new OS for car infotainment system

To write a new OS: Go and study CS at degree level for 3-4 years. Gain several years experience of using different OSs to learn what is good, what is bad, and what is ugly. Study the internals of an existing OS (probably Linux, certainly something with Open Source). Take a year or two to write your ...
by davidcoton
Sat Jul 11, 2020 2:09 pm
Forum: General discussion
Topic: Pi 4 with 10' power cable
Replies: 5
Views: 214

Re: Pi 4 with 10' power cable

You need chunky, thick cables to avoid too much voltage drop on a 10' length at 5V. One alternative is to use a 12V supply and a 12V to 5V buck converter at the Pi. Another is to use POE with the official HAT and an Ethernet hub with POE injection. EDIT: Or use an extension mains cable so the PSU re...
by davidcoton
Sat Jul 11, 2020 9:42 am
Forum: Beginners
Topic: Can the Pi 4 communicate over the USB C port?
Replies: 5
Views: 206

Re: Can the Pi 4 communicate over the USB C port?

The problem is with power, not comms. You need to check whether 2A per Pi will be adequate in your application. Headless with no peripherals should be OK. Working hard with even as SSD as local storage might be a problem. "Spinning rust" disks are almost certainly out. Look out for posts here about ...
by davidcoton
Fri Jul 10, 2020 9:55 pm
Forum: Beginners
Topic: How to recover deleted files?
Replies: 5
Views: 134

Re: How to recover deleted files?

Installing any undelete utility on the affected card may overwrite the deleted files, making them permanently irrecoverable. If they are important, you should immediately stop using the card concerned, build a rescue system with whatever utilities you want to try, boot it then connect the original c...
by davidcoton
Fri Jul 10, 2020 9:43 pm
Forum: General discussion
Topic: RPi to old TV set up...
Replies: 22
Views: 533

Re: RPi to old TV set up...

It's usually very simple to add a composite input to these old CRT TVs, True but not a good thing to do, as you said... Zappy Zappy sad :( Even if you don't get a shock, the chassis not being isolated from mains will result in potential destruction of anything connected, and a shock risk to anyone ...
by davidcoton
Thu Jul 09, 2020 9:07 pm
Forum: General discussion
Topic: Powerswitch that prevents startup after powercut
Replies: 16
Views: 498

Re: Powerswitch that prevents startup after powercut

With a 2-port USB supply, you can just take the 5V supply from the second port, fit a voltage divider, and monitor that directly on a GPIO input. No need for a relay or router. (If you are paranoid, use an opto-isolator. But there's not much point when the signal is derived from the same supply that...
by davidcoton
Thu Jul 09, 2020 8:40 am
Forum: Off topic discussion
Topic: How many pi's do YOU own?
Replies: 33
Views: 964

Re: How many pi's do YOU own?

GlowInTheDark wrote:
Thu Jul 09, 2020 3:27 am
As I said, people CAN'T just ignore it and move on. They have to make inane comments to prove themselves mods, if only in their minds.
Actually they can. Many of my posts get totally ignored. No comment on whether that is justified, but it can be done.
by davidcoton
Thu Jul 09, 2020 8:36 am
Forum: General discussion
Topic: Updated raspi-config - Boot Eeprom options
Replies: 18
Views: 901

Re: Updated raspi-config - Boot Eeprom options

Should the inclusion of EEPROM setting and boot order option in raspi-config be considered evidence that USB MSD booting is not at "critical" status? "Critical" is upgrades that have security or other serious reasons for inclusion. AFAIK there is nothing in USB booting that qualifies. At some point...
by davidcoton
Thu Jul 09, 2020 8:29 am
Forum: General discussion
Topic: Raspberry Pi Zero with micro HDMI
Replies: 21
Views: 650

Re: Raspberry Pi Zero with micro HDMI

The original goal, as I understand it, was to as close as possible to a zero cost computer. $5 is pretty darned close. Since then, the utility of WiFi for enough people justified the addition, at additional cost. Since the WiFi chip supports it anyway, BT was--essentially--free. We now have the sit...
by davidcoton
Wed Jul 08, 2020 9:19 pm
Forum: Beginners
Topic: LED help
Replies: 17
Views: 400

Re: LED help

The other rule for selecting a resistor is "Start high, reduce slowly". Particularly where the V f is almost as high as the supply voltage, random variations between LEDs will make a big difference. You need to calculate for the lowest possible V f , and the low end of the current range (not more th...
by davidcoton
Wed Jul 08, 2020 8:57 pm
Forum: General discussion
Topic: A plea for Pi package naming consistency
Replies: 13
Views: 520

Re: A plea for Pi package naming consistency

"raspi-", "rp-", "rpi-", plus "raspberrypi-" elsewhere : I like this idea. Maybe on Monday all programs could start with rp-, then on Tuesday with rpi-, Wednesday could be rasp-, Thursday pios-, Friday raspi- and on Saturday and Sunday all the Pi related packages could take a rest. Why not go the w...
by davidcoton
Wed Jul 08, 2020 5:37 pm
Forum: Off topic discussion
Topic: How many pi's do YOU own?
Replies: 33
Views: 964

Re: How many pi's do YOU own?

NOTAPOLL:

Do you like polls on this Forum?
  • Yes
  • Maybe
  • Know
  • Don't No
  • 42
  • π
  • :roll:
  • Other (Please don't specify)
You can't view the results, because there aren't any.

With apologies to anyone who is offended.
by davidcoton
Wed Jul 08, 2020 10:50 am
Forum: Troubleshooting
Topic: Raspberry Pi 1 B not starting up
Replies: 14
Views: 354

Re: Raspberry Pi 1 B not starting up

Most likely mistake is connecting the adapter's power pin (5v) to anything except a 5V pin on the GPIO header.
Or even connecting it there with another PSU connected.
Or leaving it unconnected and it accidentally touched something on the Pi.
by davidcoton
Wed Jul 08, 2020 10:33 am
Forum: Beginners
Topic: New to Raspberry Pi: Errors and weird messages on first boot
Replies: 22
Views: 577

Re: New to Raspberry Pi: Errors and weird messages on first boot

This is because "apt" is set up to assume you are there to answer questions, while "apt-get" assumes it is used in an unattended script, so there is no point in asking. Not strictly true because 'apt-get' does ask if one wishes to proceed in the majority of cases. But it is true that 'apt' is more ...
by davidcoton
Tue Jul 07, 2020 11:13 pm
Forum: General discussion
Topic: apt --fix-broken install
Replies: 2
Views: 152

Re: apt --fix-broken install

Exactly what did you run to "get all of the needed packages"? The recommended commands are sudo apt update sudo apt full-upgrade I can't guarantee that they will fix your problem, but they stand a better chance than most others. You might also want to try sudo apt update sudo apt --fix-broken instal...
by davidcoton
Tue Jul 07, 2020 8:46 pm
Forum: Beginners
Topic: Just got my RP4B - boot question
Replies: 4
Views: 233

Re: Just got my RP4B - boot question

Forget NOOBS. If you need a boot selector for multiple OSs, use PINN. USB boot does not work out of the box, yet. Start with an SDCard, get that working, then swap to your SSD. Note that USB boot is only recently released from beta, I don't think the instructions are fully up to date, though I can't...
by davidcoton
Tue Jul 07, 2020 8:22 pm
Forum: General discussion
Topic: Need advice on choosing Pi3B+ and Pi4 4GB
Replies: 16
Views: 501

Re: Need advice on choosing Pi3B+ and Pi4 4GB

It looks like in the Pi world, there is no universal case or cooling solution. One has to choose based on the application and if one wants to use it for another project, one has to buy another case and perhaps also cooling solution. Just as there is no universal roof rack for every model of Ford ca...
by davidcoton
Tue Jul 07, 2020 8:14 pm
Forum: Beginners
Topic: Thought this was going to be easy... Monitor ...
Replies: 6
Views: 266

Re: Thought this was going to be easy... Monitor ...

What are you using as a power supply?
by davidcoton
Tue Jul 07, 2020 8:12 pm
Forum: Beginners
Topic: New to Raspberry Pi: Errors and weird messages on first boot
Replies: 22
Views: 577

Re: New to Raspberry Pi: Errors and weird messages on first boot

In my recent experience, "upgrade", "full-upgrade", "dist-upgrade" seem to do the same thing whether one uses 'apt' or 'apt-get'. It is recommended by the Foundation to use 'apt' but I have not hit any issue using 'apt-get' instead. It's using "full-upgrade" over "upgrade" which is the important pa...
by davidcoton
Tue Jul 07, 2020 11:11 am
Forum: Beginners
Topic: GPIO input and output on same rpi
Replies: 1
Views: 51

Re: GPIO input and output on same rpi

Question: 1. Is this possible? 2. I am new to electronic, I am thinking use one jumper wire to connect GPIO pin 12 to GPIO pin 23, and another jumper to connect 2 GND pins. Will this achieve what I want or will it damage my Pi? Answer: Yes The connection between ground pins is unnecessary, they are...
by davidcoton
Tue Jul 07, 2020 9:46 am
Forum: General discussion
Topic: FPGA Development Software for RPI 4?
Replies: 64
Views: 1643

Re: FPGA Development Software for RPI 4?

Wonder if Verilog can handle Ternary Logic? https://en.wikipedia.org/wiki/Three-valued_logic https://en.wikipedia.org/wiki/Ternary_computer https://rosettacode.org/wiki/Ternary_logic Ternary is closer to fuzzy logic and similar to your diode curve output function. ... The Russians made Ternary comp...
by davidcoton
Mon Jul 06, 2020 9:57 pm
Forum: Beginners
Topic: Over-Voltage and Over-Current protection circuit
Replies: 10
Views: 343

Re: Over-Voltage and Over-Current protection circuit

Actually, yes every conceivable attack. the wires are just coming from 8 GPIO to keypad matrix and I2C to sda scl pins and last the vcc and gnd to lcd from the pi hence 4 wires from lcd. i want to protect all these wires/pins from any attack as they are placed outside. ofcourse protection > cost bu...

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