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by tommylovell
Wed Dec 30, 2020 9:14 pm
Forum: Ubuntu
Topic: Booting a Pi4 when multiple SSD/USB drives are connected?
Replies: 5
Views: 560

Re: Booting a Pi4 when multiple SSD/USB drives are connected?

I know similar concepts are possible on Windows, but I'm still fairly new to Linux and not sure if this idea is possible with a Pi 4 and Raspian, or similar Linux OS. FYI., this is possible with other Linuxes that use GRUB/GRUB2 as a bootloader and are on a machine with a BIOS. But the Pi does not ...
by tommylovell
Sun Oct 11, 2020 5:18 pm
Forum: Troubleshooting
Topic: Under-voltage detected! in DMESG
Replies: 25
Views: 693

Re: Under-voltage detected! in DMESG

the simplest fix is to get the much recommended RPF PSU specifically designed for the RPi3B+ another is to use any PSU (not just any chargers please) with 2.5A or higher rating and with a microUSB cable with thicker wire cores (AWG18) most of my RPis (including this RPI4B-4G desktop) are now powere...
by tommylovell
Sat Oct 10, 2020 4:52 pm
Forum: Troubleshooting
Topic: Under-voltage detected! in DMESG
Replies: 25
Views: 693

Re: Under-voltage detected! in DMESG

Only Pi4 has resident firmware. The other boards have an inalterable boot loader and load everything else from the boot medium. It's a hardware issue no doubt. The Pi board has power requirements and the power the Pi can supply to USB devices (assuming the PSU is up to snuff) is limited to 1.2A, so...
by tommylovell
Sat Oct 10, 2020 4:45 pm
Forum: Troubleshooting
Topic: Under-voltage detected! in DMESG
Replies: 25
Views: 693

Re: Under-voltage detected! in DMESG

Have you tried an official power supply? On my (only) Pi4 I have an official RPi Foundation power supply; all other Pi's have either a 2.5A, 2.1A Adafruit, or a cheapo Amazon 2A. I'll use a USB-C to micro adapter to try the Pi4 supply. I'm 1) curious; and, 2) cheap and disinclined to buy another po...
by tommylovell
Sat Oct 10, 2020 4:06 pm
Forum: Troubleshooting
Topic: Under-voltage detected! in DMESG
Replies: 25
Views: 693

Under-voltage detected! in DMESG

I have a Pi (3B+, I think) that used to have its O/S on a USB drive. Every few days it would drop dead, so I retired it. I recently put it back in service with a USB Flash Drive hosting the O/S. I found this in DMESG: [47124.394081] Under-voltage detected! (0x00050005) [47128.554071] Voltage normali...
by tommylovell
Wed Dec 11, 2019 11:31 pm
Forum: Troubleshooting
Topic: mmcblk0 unnaccessable
Replies: 10
Views: 1161

Re: mmcblk0 unnaccessable

For future reference, you could do this:

Code: Select all

sudo sh -c "xzcat genpi64.img.xz > /dev/sda && sync"
by tommylovell
Wed Dec 11, 2019 5:49 pm
Forum: Advanced users
Topic: All the iSCSI solutions for Raspbian
Replies: 3
Views: 2771

Re: All the iSCSI solutions for Raspbian

Simple answer to your kernels question. Google: kernel types in Raspbian 10 - Buster (or see: https://raspberrypi.stackexchange.com/questions/104722/kernel-types-in-raspbian-10-buster). One answer is: kernel.img is 32-bit for BCM2835 (RPi1 & Zero) kernel7.img is 32-bit for BCM2836 (RPi2) and BCM...
by tommylovell
Wed Dec 11, 2019 4:04 pm
Forum: Advanced users
Topic: SSH with RSA keys for MPI cluster
Replies: 4
Views: 470

Re: SSH with RSA keys for MPI cluster

This post is a little over a month old, but I'll toss my 2cents in. I don't think that there is a way around having to supply credentials at east once. I have a private Evernote article I reference when I have a new machine that has this command for each system that I maintain: ssh-copy-id -i .ssh/i...
by tommylovell
Sun Aug 04, 2019 1:58 pm
Forum: Troubleshooting
Topic: PI4 red light no boot
Replies: 8
Views: 750

Re: PI4 red light no boot

There is not much to go on in your original post, so the assumption is that your SD card has not yet been properly set up. The web page to do that is https://www.raspberrypi.org/documentation/installation/installing-images/README.md . It has a link to where you can find images of Raspbian that you c...
by tommylovell
Mon Aug 17, 2015 12:46 am
Forum: Beginners
Topic: Motorola Lapdock 100 burned out by RPi 2
Replies: 6
Views: 2363

Re: Motorola Lapdock 100 burned out by RPi 2

"You should have opened your USB A cable and cut the red wire." When my new Lapdock arrives on Tuesday I'll implement your suggestion. It should be simple to do. "If you have a friend into electronics, he/she might be able to replace the fried component/s and recover the Lapdock.&quo...
by tommylovell
Sun Aug 16, 2015 1:38 pm
Forum: Beginners
Topic: Motorola Lapdock 100 burned out by RPi 2
Replies: 6
Views: 2363

Motorola Lapdock 100 burned out by RPi 2

I'm hoping that this is a true beginners question and can be answered easily. From the following text you can see that 1) I'm not an engineer, and 2) I'm lazy and tend to "try things" rather than research and understand them. I have: a Motorola Lapdock 100; CY 20cm Type D Micro HDMI Socket...
by tommylovell
Sun Aug 16, 2015 1:08 pm
Forum: Beginners
Topic: Raspberry Pi 2 + Lapdock?
Replies: 1
Views: 403

Re: Raspberry Pi 2 + Lapdock?

Hi Lyth. I saw your very old unanswered post just now. I don't know if you had any luck with it. I had a model B work perfectly with a Motorola Lapdock 100. No joy with the RPi 2, but I didn't follow the cabling that others have followed with success. Just fyi, I am posting a question in the Beginne...
by tommylovell
Mon Jul 27, 2015 12:16 pm
Forum: Troubleshooting
Topic: Wi-Fi drops when ethernet unplugged
Replies: 2
Views: 685

Re: Wi-Fi drops when ethernet unplugged

I've found that I have a compound problem. The one I've described on the subject line; and another where my WiFi adapters become unresponsive, necessitating plugging in the ethernet, or plugging in a keyboard and blindly logging in (as these systems are headless). I'm no expert in this and was compl...
by tommylovell
Sun Jul 19, 2015 8:42 pm
Forum: Troubleshooting
Topic: Wi-Fi drops when ethernet unplugged
Replies: 2
Views: 685

Wi-Fi drops when ethernet unplugged

I have two Raspberry Pi's that are acting differently with the same image installed. One is an old Model B, the other is a new(ish) RPi 2. The Wi-Fi works properly with a Realtek Wi-Fi adapter installed and there is no ethernet cable. The Wi-Fi works fine when an ethernet cable is plugged into the R...

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