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4

TL;DR The external hard drive is powering the RPI after you remove the microUSB power supply. This is called Backfeeding. This is not unusual for raspberry pi's. Is it bad for the pi I would advise against backfeeding because there is little protection for the Pi. You would need to ensure there is a stable voltage and current to avoid damage. I would ...


3

USB is a standard and must have 5V. The 12V you mention are the output ratings for the HUB's power supply. To be compatible with USB there must be an additional DCDC converter inside the HUB. Whether this HUB is capable of driving 2 RPis or not depends on the current it can provide, not its output voltage. A voltage of ~5.5V must not be exceeded! Note that ...


3

As joan pointed out in the comments above, there were extra spaces after "Keycard"


3

I can confirm, after having used the Bela shield on top of a Beaglebone Black, that its latency is extremely low (<1ms) and quite capable of doing calculations on audio. The normal shield has 2 jack microphone inputs and 1 jack stereo output. Strictly speaking, you have to buy the version that comes with jack adapters, though. I do believe more inputs/...


3

Since all RPi use b8:27:eb as the first three octets of their MAC address, you can use arp from your Mac/Linux PC, but you'll need to refresh the arp cache first. Here's a bash script that will do the job. You can get more details from my github page on the subject. #!/bin/sh : ${1?"Usage: $0 ip subnet to scan. eg '192.168.1.'"} subnet=$1 for addr in `...


3

Yes, there are official updates to this issue. Eben Upton has said that there won't be any 64 bit Raspbian yet, because they want to maintain backwards compatibility with older systems and do not have the resources to maintain a 32 bit OS and a 64 bit OS. However, there are other alternative operating systems that are compiled for arm64 on the Raspberry Pi, ...


2

I don't know what version of the Pi you use, but from version 3 onward it may be possible to boot from network: https://www.raspberrypi.org/documentation/hardware/raspberrypi/bootmodes/net_tutorial.md How to PXE Boot a Pi 3? But it seems like it requires a bit of preparation and configuration. At work, we just configured one PI that fits our needs (base ...


2

As you are told by systemd: zfs-import.service is not a native service, redirecting to systemd-sysv-install. Old style SysV init system is deprecated and not used anymore. For compatibility it is only emulated by systemd but there are limitations. Look at Compatibility with SysV. If you encounter problems with SysV emulation then the first step should ...


2

The value 1437495737 is in hex 55ae71b9, or in little endian notation b9 71 ae 55 while the integers 185 113 174 85 are in hex also b9 71 ae 55. So you get the same value, just in different representation.


2

It is exactly determined what the Raspberry Pi 3B+ is able to do with its WiFi on-board device. With the command iw you can show what interface combinations are possible. Just execute $ sudo iw list | grep -A4 "valid interface combinations:" valid interface combinations: * #{ managed } <= 1, #{ P2P-device } <= 1, #{ P2P-client, ...


2

The error generally means that you have called a function that does not have a prototype. In this case I think you mistyped the function, capitalizing the 'L' where you should have lower case 'l'. Note the difference between the one that you commented out and the ones that follow, copying from your code in the question: //bcm2835_gpio_fsel(uint8_t pin, ...


1

I found this is the bug in Raspbian kernel. https://github.com/raspberrypi/firmware/issues/1005


1

For anyone having the same issues: It turns out that the above code uses too little CPU load and therefore does not shoot up the frequency. When I checked, my CPU was constantly running at 700 Hz. To achieve the required FPS on the above resolution, I changed my cpufreq governor from ondemand to performance. This might not be the only or the best solution, ...


1

As you have noted GPIO pins retain their state when shutdown. There are a couple of exceptions where the state is modified by the shutdown process. gpio-poweroff (which is designed for this purpose) is the most reliable method. See https://raspberrypi.stackexchange.com/a/94399/8697 PS RUN and EN pins are INPUTS, and NOT connected to the GPIO. RUN is ...


1

This howchoo post shows how to connect an LED to show the status of the Pi. The LED is steady on when the Pi is running, and off after shutdown. Briefly: Add this line to /boot/config.txt, and reboot enable_uart=1 Connect the TxD pin (GPIO pin 8) to the positive lead of a 2 or 3 volt LED. Connect a ground pin (e.g. GPIO pin 6) to a 330 ohm ...


1

If the drive is supplying 5V power to the USB port, it will power the Pi. As this is unusual, and not complying with the USB spec, no one can say if it is safe. NOTE You can not power a Pi through its USB ports, although once booted it will continue to run.


1

This answer on Unix Stack Exchange helped me. I needed to open ~/.config/chromium/Default/Preferences and add a window_placement key under browser containing: "window_placement": { "bottom": 800, "docked": false, "left": 0, "maximized": true, "right": 480, "top": 0 }


1

I found one not very good solution, which is suitable to my problem for now. I managed to output the whole video signal (not only the camera video) via 3.5mm TV output. Then I ran a script to make the camera video full screen, and got the camera video on the receiver screen.


1

If there is no 3.3V the Pi is DEAD! No script can damage the Pi (although it can corrupt the OS - as can pulling the plug). NOTE poking a voltmeter at the header pins is a BAD idea. Even it the Pi wasn't dead, a momentary short between the 3.3V & 5V pins (which are adjacent) is invariably fatal.


1

You installed the tor service that can only be used by applications directly. At the tor project you will find at Configure your applications to use Tor: If you want to use Tor for anonymous web browsing, please use Tor Browser. It comes with readily configured Tor and a browser patched for better anonymity. To use SOCKS directly (for instant messaging, ...


1

What do you mean by image is corrupted ? If it's an installation issue with WIn32DiskImager, here's my experience: I just installed Raspbian on an SD Card this morning and I got an error too but went to Raspbian official doc and found Etcher which work really well and even have a portable version ! Here's the release page of their Github, you'll find what ...


1

PiCorePlayer to the rescue. For now, I'm using a dedicated 3B+ as music server running piCorePlayer serving music via BlueTooth to either a BT speaker (UE Boom 2) or Logitech BT audio adapter which feeds my stereo. The BT connection runs in 'beta' mode, so it may not be fully baked yet. I do find that to change speakers, I have to reboot to complete the ...


1

Based on the answer by Ingo, I went and made a script to do this job. https://github.com/Autodrop3d/raspiApWlanScripts The gist is that there's one script to run that'll setup the Pi for reboot-less AP/STA switching and then there are helper scripts that'll actually do the switching for you.


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