General Raspberry Pi stuff

[Neal]

Welcome to the all encompassing Raspberry Pi thread. A collection of random stuff about the RPi.

Raspberry Pi's are great little things and as a few of us here are putting them to good use I thought it might be a good idea to share ideas and tips on how to use them, mainly so I can learn more from Jack(Nick)/Nick etc. And maybe encouraging others to find a use for them too.

One obvious use is as a music/multimedia player using a TopHat addon board IE:DAC etc to stream audio and video. There seems to be quite a few s/w choices available like volumeIO, Runeaudio, picoreplayer, max2play, mopidy, Moode etc.

I use max2play, it works as a squeezebox and can run LMS if required along with Kodi(XBMC) plus other neat stuff. I run a I2S feed from the RPi to my Arcam TDA1541a DAC board, upsampling it along the way, works a treat.

I have one as a DNS and DHCP server at home running pihole mainly because I no longer wanted to use BT's DNS servers and I wanted to block various tracking services...but BT wouldn't let me change (they have since introduced an opt out setting in my on-line account profile) putting a warning on screen about how they don't allow alternative DNS servers like Google or OpenDNS.

I have another being used as a simple 2x IP camera CCTV system with external USB storage using zoneminder as the controlling s/w. This one is an RPi2 as well and copes OK with 2 cameras at 10~12 fps any more though and it collapses. The RPi3 maybe better but I would limit the connections to 2 cameras anyhow.

More recently I've been using the latest RPi3B as a low powered desktop which is working out OK within limits.

As a desktop the RPi3B is way better than the previous 2B but it does fall short in a number of areas. It is still limited to 1GB of mem and you have to give some of that up to the GPU for the desktop plus it lacks a proper on/off switch, although there is a neat solution around that. Also, I'm not sure of the durability of SD cards in a desktop environment and maybe a USB SSD or mSATA drive would be better for longevity, there are mSATA tophat adapters available from Element14 I believe....

[Neal]

On/off sitches.
You can shut the RPi down from the desktop but there is no way to do a controlled shutdown via hardware as standard. Power on is ok if you use a physical switch in the PSU lead but it should never be used to power off as the SD card may get corrupted.

There seems to be a number of DIY and addon options available that allow for a controlled shutdown which is fine but I found a neat DIY solution that uses some simple python code and a pair of miniture NormallyOpen momentary switches.

Essentially all the info is here: https://github.com/TonyLHansen/raspberr ... ff-switch/

Im just using the press and hold scipt set to 4 seconds, it works a treat. The instructions to modify rc.local are a bit thin but all you do is enter the call to the script before the 'exit 0' IE: in mine it is 'python /home/pi/shutdown-with-hold.py &'

To boot the RPI if power is already attached I installed another switch in the unpopulated 'run' pads near the top hat header pins 39 and 40, as shown in the link. I think this is really a reset switch so it should not be used if the RPi is already up and running.....maybe use it only if your RPi locks up for some reason!

Anyhow, enjoy.

[Nick]

This looks like a non free solution to shutdown.

https://www.rapidonline.com/pimoroni-pi ... roni%20CON

[Ray P]

There are some interesting RPi DAC and associated hardware boards around at allo, like the Kali Reclocker;

https://www.allo.com/sparky/kali-reclocker.html

check out the other products on the website too.

They're currently working on a new DAC based on the recently introduced ESS9028/38 DAC chip family.

[Neal]

Cheers Nick, good price really.

Cases.
Tons available, the new RPi3 one is neat but no room for a tophat and no ventilation which is a consideration if you want to overclock.

Whilst on overclocking the RPi3 can now only be overclocked by modifying /boot/config.txt. Just so you know.

This is my preferred case:


From DesignSpark @ RS components and other good re-sellers. If you fit heatsinks to your Pi you'll need to do a bit of work on the internal plastic bits to make it fit. The case is ventilated well, perforated base, an air gap all the way around the top cover with a ventilated Raspberry logo on top. Unfortunately there are no holes to see the LEDs but you can easily add a couple next to the SD card slot.

If adding a DAC tophat, HiFi Berry etc you are better off with their designer case as it will have the correct cutouts already made.

[Neal]

Link to the Pimoroni SHIM shop web site Nick linked to earlier

https://shop.pimoroni.com/collections/r ... onoff-shim

[Neal]

Helpful for those new to Linux: https://www.makeuseof.com/tag/15-useful ... ould-know/

Some others I've picked up, the obvious for updates
sudo apt-get update (package index update)
sudo apt-get upgrade (package upgrade)
sudo rpi-update (firmware and Kernel updates - ONLY DO IF REQUIRED/INSTRUCTED)

sudo apt-cache search 'package name' (searches for that package in the repository)
sudo apt-cache policy 'package name' (gives the version number of the package)

sudo apt-get check (checks for broken package dependencies)

sudo su (switch to Admin level so you don't need to type sudo on every command!)

[Neal]

The default swap size when using the SD card is 100MB. I've maxed it out using the Pi as a desktop a couple of times. You can increase it by editing dphys-swapfile IE sudo nano /etc/dphys-swapfile

Find the line with 100 and change it to 200, cntrl-o to write it out, cntrl-x to exit. reboot.

htop is a good command to see the performance of all 4 cores, the memory allocation and swap usage, just run it from the command line. It's part of the latest 'stretch' build of Raspbian.

[pre65]

I see there is a RP 3 B+ now.

http://view.e-marketing.premierfarnell. ... 741177&r=0

[Neal]

Yup already ordered!

[Neal]

Little bit of PWR saving if running headless, turn off the hdmi port. For the OCD streamers it may help sound quality ?

Edit /etc/rc.local and add the following lines above exit 0:

# Disable HDMI
/usr/bin/tvservice -o

Or from the cli
/opt/vc/bin/tvservice -o

-p to turn it back on

[jack]

Yup already ordered!

PoE is long overdue. I've used RPis to turn big TVs into wallboards for Jira and similar - these had to be PoE and the PoE adapters were the same size as the Pi!

The 3B+ is a nice upgrade which ticks a whole load of boxes for stuff that was just not fully implemented...

[Neal]

Yup, think the product has matured nicely with this latetest version, although POE is via a top hat.

I’m trialing yodeck for a customer at the moment to cover their digital signage needs...

[Neal]

Aha! My Pi3 B+ has finally arrived....

[Neal]

This is so much faster, impressive.

Make sure to upgrade your OS install (stretch) if planning to go from a 3B to 3B+, it wont boot otherwise