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by rpdom
Fri Jun 18, 2021 12:16 pm
Forum: Advanced users
Topic: startx at boot single client and unprivileged user
Replies: 28
Views: 717

Re: startx at boot single client and unprivileged user

Only if run from root's crontab. The cron daemon may be running as root but processes in a normal user's crontab are run by that user. I'd expect someone claiming years of linux experience to know that. I think that "drtechno" is referring to the /etc/crontab file for some reason. Not the...
by rpdom
Fri Jun 18, 2021 11:55 am
Forum: C/C++
Topic: atomic or volatile, that is the question ( Whether 'tis nobler in the mind to mutex them)
Replies: 46
Views: 1048

Re: atomic or volatile, that is the question ( Whether 'tis nobler in the mind to mutex them)

Heater, you stated already by yourself: At least I think so. Anyone know better? so let's just wait if anyone knows better, ok? Many people have already stated (or implied) that what you are trying to do is NOT a beginner subject. In fact most professionals wouldn't do it like that. You keep claimi...
by rpdom
Fri Jun 18, 2021 11:48 am
Forum: Advanced users
Topic: startx at boot single client and unprivileged user
Replies: 28
Views: 717

Re: startx at boot single client and unprivileged user

Yes, that stops user ecks from gaining elevated privileges but it doesn't solve the other problem: calling start /path/to/program as ecks from rc.local, cron, or a systemd service. Use of a user with restricted rights was implied in options 3 & 4 of my OP. If its executing inside cron, then its...
by rpdom
Fri Jun 18, 2021 10:54 am
Forum: Troubleshooting
Topic: PW recovery failed; init=/bin/sh doesn't work
Replies: 3
Views: 92

Re: PW recovery failed; init=/bin/sh doesn't work

Not sure it is affecting it, but I'd try removing the "modules-load=dwc2,g_ether" part as well, as that is setting up the USB in device mode to be an Ethernet adaptor, which could prevent any USB devices from working.
by rpdom
Thu Jun 17, 2021 7:58 am
Forum: Troubleshooting
Topic: Onboard bluetooth comms between RPi 3s
Replies: 2
Views: 126

Re: Onboard bluetooth comms between RPi 3s

You need to exit from the "[bluetooth]#" prompt before you can type that command. Just "exit" or "quit" or pressing Ctrl and D should do it.
by rpdom
Tue Jun 15, 2021 3:16 pm
Forum: Troubleshooting
Topic: Download screen software on Pi 3b+
Replies: 5
Views: 103

Re: Download screen software on Pi 3b+

But the description conflicts with: tried to install using the add/remove feature in the menu, and found screen 4.6.2-3, but when I ask the pi to install from there is says it installs If Add/Remove can't download new index files, it will use the stored index files to determine what it thinks shoul...
by rpdom
Tue Jun 15, 2021 8:30 am
Forum: Raspberry Pi OS
Topic: Can you please stop deleting old package versions from the repository index?
Replies: 4
Views: 300

Re: Can you please stop deleting old package versions from the repository index?

The index is only supposed to have the current versions of software in.

If the files are still there and you feel you need to use that particular version you can try downloading the file and installing it with dpkg. You'll have to manually sort out dependencies.
by rpdom
Mon Jun 14, 2021 6:22 pm
Forum: Troubleshooting
Topic: Pi 3b+ Is not working.
Replies: 4
Views: 129

Re: Pi 3b+ Is not working.

If you have access to a voltemeter, check the voltage on the 3V3 pin of the GPIO header (pin 1). Use the outside of a USB or network socket for the other connection.
by rpdom
Sun Jun 13, 2021 11:57 am
Forum: Other
Topic: Raspberry Pi OS or another Distribution for a systemd free server?
Replies: 25
Views: 2173

Re: Raspberry Pi OS or another Distribution for a systemd free server?

Generally I don't need automounting. When I insert a USB storage device it is usually because I want to format it, partition it or just install an image on it. On some of my Raspberries I do have devices that need to be mounted, but that is all at boot time, so I do that in other ways. Occasionally ...
by rpdom
Sun Jun 13, 2021 6:14 am
Forum: Camera board
Topic: Do I have a faulty csi port?
Replies: 5
Views: 293

Re: Do I have a faulty csi port?

I figured no one would see it in the original place it was posted. It fits in here. :) In that case what you should have done is to click the "Report Post" icon and ask that it be moved to the correct place. The moderators are very happy to do that for you. Too late now, They will have to...
by rpdom
Sun Jun 13, 2021 5:54 am
Forum: Automation, sensing and robotics
Topic: Looking to dim LEDs with a digital slider bar
Replies: 6
Views: 321

Re: Looking to dim LEDs with a digital slider bar

You may want to check this out: https://www.w3schools.com/nodejs/nodejs_raspberrypi_rgb_led_websocket.asp That looks like a decent way to control an RGB strip. Just a couple of things I noticed. He keeps saying that you need MOSFETs that will turn on at 5V or lower. Really they need to be 3.3V or l...
by rpdom
Sat Jun 12, 2021 5:19 pm
Forum: Troubleshooting
Topic: External disc (HDD, Pi 3, USB 2): Bad transfer rates
Replies: 10
Views: 252

Re: External disc (HDD, not SSD): Bad transfer rates

andrum99 wrote:
Sat Jun 12, 2021 4:42 pm
See sticky near the top of this forum: viewtopic.php?f=28&t=245931. Nothing to do with which filesystem the drive has on it.
Not applicable, as the OP is not using a Pi 4.
by rpdom
Sat Jun 12, 2021 2:40 pm
Forum: Troubleshooting
Topic: Raspberry Pi Server Issues
Replies: 10
Views: 390

Re: Raspberry Pi Server Issues

Crypto is used for a lot more than just mining currencies. Any secure connection, like SSH or VPN will use cryptography.
by rpdom
Sat Jun 12, 2021 1:59 pm
Forum: General discussion
Topic: Is it possible to receive data from the USB-C port of the Raspberry Pi 4?
Replies: 8
Views: 333

Re: Is it possible to receive data from the USB-C port of the Raspberry Pi 4?

Only if your iPad can supply the Pi with enough current at 5V. Otherwise you'll need to find some other way of powering it.
by rpdom
Sat Jun 12, 2021 8:45 am
Forum: General
Topic: PicoVGA - VGA/TV display on Raspberry Pico
Replies: 29
Views: 1205

Re: PicoVGA - VGA/TV display on Raspberry Pico

I want to store a full framebuffer, so at 640x480 pixels that's 38.4 kb to store for each on/off colour channel. So I guess I could store three, single-bit colour channels in the Pico RAM -- provided they're packed properly. I think I'd look at having one word for red, one for green and one for blu...
by rpdom
Sat Jun 12, 2021 6:07 am
Forum: Raspberry Pi OS
Topic: Need help WIFI issue, was directed here from Retropie forum mod
Replies: 4
Views: 284

Re: Need help WIFI issue, was directed here from Retropie forum mod

I couldn’t get a definitive idea either of the exact chipset model used in that hubpiwi device. In the hubpiwi I've got, it has an RTL8188EUS chip on it. At least, that's what is printed on the chip. It might identify as something else. It's been a while since I've used it, so don't know if the rig...
by rpdom
Fri Jun 11, 2021 6:59 pm
Forum: Advanced users
Topic: Pi 2B Schematic help - PWM audio voltage divider?
Replies: 5
Views: 160

Re: Pi 2B Schematic help - PWM audio voltage divider?

Well, from a brief look at that schematic, I can see that U11 is powered from the 2.5V Audio supply rail. So giving it an input of 3.3V would exceed its supply voltage resulting in clipping of the output. First sentence is correct. Second one is not. The input and output signals of U11 are digital....
by rpdom
Fri Jun 11, 2021 6:51 pm
Forum: General discussion
Topic: ssd disk
Replies: 20
Views: 773

Re: ssd disk

W. H. Heydt wrote:
Fri Jun 11, 2021 6:47 pm
so the true limit is the single PCIe lane, at 4 Mt/s.

(Side note... an 'm' prefix is 'milli-', so 1mb/s would be 0.001 b/s.)
That would be very slow. Is the "t" in Mt/s "tortoises"?
by rpdom
Fri Jun 11, 2021 6:48 pm
Forum: Advanced users
Topic: Pi 2B Schematic help - PWM audio voltage divider?
Replies: 5
Views: 160

Re: Pi 2B Schematic help - PWM audio voltage divider?

Well, from a brief look at that schematic, I can see that U11 is powered from the 2.5V Audio supply rail. So giving it an input of 3.3V would exceed its supply voltage resulting in clipping of the output.
by rpdom
Fri Jun 11, 2021 6:21 pm
Forum: General discussion
Topic: ssd disk
Replies: 20
Views: 773

Re: ssd disk

Onq28 wrote:
Fri Jun 11, 2021 6:00 pm
I was thinking of something like the samsung portable SSD T5 wich has
read speed of 540 mb/s. I could go for higher speed but the usb bus of the Pi 4 is limited as far as i know to 480 mb/s.
That's just the USB2 speed. The two USB3 ports support up to 5000 mb/s between them.
by rpdom
Fri Jun 11, 2021 6:02 pm
Forum: Automation, sensing and robotics
Topic: 3 volt chip led with relay ?
Replies: 14
Views: 491

Re: 3 volt chip led with relay ?

Absolutely fine to run directly from a Pi and should be quite bright. Advice from rpdom, virtually always spot on, maybe not here though because that does not appear to be your typical T1-3/4 version but one of those higher power COB chips. Not sure but could be popular 2 watt or 5 watt so will not...
by rpdom
Fri Jun 11, 2021 5:09 pm
Forum: General discussion
Topic: Porting old Pi3 distribution to pi4.
Replies: 27
Views: 795

Re: Porting old Pi3 distribution to pi4.

My PC runs Ubuntu 20.04. If I would still have the harddisk from ubuntu 12.04 that would still work. Presumably from the same PC, so not surprising. It may not have all of the drivers needed for the newer hardware though. So why doesn't the older system work on pi4? There has to be an explanation o...
by rpdom
Fri Jun 11, 2021 3:50 pm
Forum: General
Topic: What are these duplicate function pins?
Replies: 6
Views: 372

Re: What are these duplicate function pins?

Yes, all can be connected to the SPI hardware. You just choose which ones that is.
by rpdom
Fri Jun 11, 2021 1:37 pm
Forum: General discussion
Topic: ssd disk
Replies: 20
Views: 773

Re: ssd disk

SSDs aren't that expensive now. You can put everything on one SSD. I have a Pi 4B running off a 120GB SSD with no SD card. The thing you have to watch with SSDs is the USB interfaces they use or the ones you use with them. Some use the JMS/JMicron controllers which don't support USB3 correctly. Avoi...
by rpdom
Fri Jun 11, 2021 11:48 am
Forum: Advanced users
Topic: What happens if the 5 V PSU input falls below the specification?
Replies: 14
Views: 502

Re: What happens if the 5 V PSU input falls below the specification?

Now I know that the Pi will complain at one point by displaying the lightning flash etc, but when the voltage falls further, does it simply crash or would this trigger a controlled shutdown? The background to this is that we have deployed a new batch of Pi Zeros The Pi Zero does not have the under ...

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