raspberrypi_setup

1. Download newest image at https://downloads.ubiquityrobotics.com/pi.html

2. VNC app on MAC/SSH on Linux//Putty on Win https://github.com/HackerShackOfficial/Raspberry-Pi-VNC-Mac

a. create wlan

sudo nano /etc/udev/rules.d/70-persistent-net.rules

Put the following content

# This file was automatically generated by the /lib/udev/write_net_rules
# program, run by the persistent-net-generator.rules rules file.

# PCI device 0x8086:0x10c9 (igb)
SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="b8:27:eb:ec:7e:88", ATTR{type}=="1", KERNEL=="wlan*", NAME="wlan0"

add modules

sudo nano /etc/modules

The contents are:

uinput
i2c-bcm2708
i2c-dev
r8712u
brcmfmac
brcmutil

Rpi-Update

Raspberry-pi OS builds sometimes include rpi-update, which updates the kernel, firmware, etc.
sudo rpi-update
You must enter 'y' to do the update, the default is no.

Zram

formerly called compcache, is a Linux kernel module for creating a compressed block device in RAM, i.e. a RAM disk, but with on-the-fly "disk" compression. When used for swap, zram (like zswap also) allows Linux to make more efficient use of RAM, since the operating system can then hold more pages of memory in the compressed swap than if the same amount of RAM had been used as application memory or disk cache. This is particularly effective on machines that do not have much memory.

A compressed swap space with zram/zswap also offers advantages for low-end hardware devices such as embedded devices and netbooks. Such devices usually use flash-based storage, which has limited lifespan due to write amplification, and also use it to provide swap space. The reduction in swap usage as a result of using zram effectively reduces the amount of wear placed on such flash-based storage, resulting in prolonging its usable life. Also, using zram results in a significantly reduced I/O for Linux systems that require swapping.

sudo wget -O /usr/bin/zram.sh https://raw.githubusercontent.com/novaspirit/rpi_zram/master/zram.sh
sudo chmod +x /usr/bin/zram.sh
sudo nano /usr/bin/zram.sh
Change 1024 to 4096
sudo nano /etc/rc.local
Find the line that says "exit 0" and add one line above it /usr/bin/zram.sh Press control+x
Press enter Reboot

RTC Problem

The Rpi doesn't have a real-time clock, and so it has to update it's time/locale everytime it's booted. When it can't do this quickly the OS has trouble assertng security keys, etc...
We'll speed this up by setting the timezone manually:
sudo nano /usr/bin/setTimezone.sh
Put this in the file:
#!/bin/bash timedatectl set-timezone America/New_York
Now, add this to rc.local so it's run every boot-up
sudo nano /etc/rc.local
Find the line that says "exit 0" and add one line above it
/usr/bin/setTimezone.sh

Kernel Build

The Rpi has v8 ARM based Broadcom 64-bit SOC, but there isn't a performance voost from 64bit kernels, so we'll just optimize the built-in kernel. Install Dependencies

sudo apt-get update && sudo apt-get -y install build-essential libisl-dev libncurses5-dev bc git-core bison flex libmpfr-dev libmpc-dev libgmp-dev texinfo libreadline6-dev curl ccache libffi-dev libelf-dev libopenblas-dev libblas-dev m4 cmake cython python3-dev python3-yaml python3-setuptools libssl-dev automake autoconf help2man gawk expect
Binutils
Download: ~4min: time wget -c https://ftp.gnu.org/gnu/binutils/binutils-2.32.tar.bz2
Decompress: ~1min: time tar xvf binutils-2.32.tar.bz2 #takes_about_one_minute
Framework: mkdir binutils-obj && cd binutils-obj
Configure: ../binutils-2.32/configure --prefix=/opt/arm --disable-nls --enable-lto
Build: ~4min: time make -j6 CFLAGS="-march=armv7-a -mtune=cortex-a53 -mfpu=vfpv4 -Ofast -ftree-vectorize -mlittle-endian -fgcse-after-reload -fvect-cost-model -pipe" CXXFLAGS="-march=armv7-a -mtune=cortex-a53 -mfpu=vfpv4 -Ofast -ftree-vectorize -mlittle-endian -fgcse-after-reload -fvect-cost-model -pipe"
Install: time sudo make -j6 install
Add2Path: echo 'export PATH="$PATH:/opt/arm/bin"'>>~/.bashrc && source ~/.bashrc
GCC
Download: ~4min: time wget -c https://mirrors-usa.go-parts.com/gcc/releases/gcc-9.1.0/gcc-9.1.0.tar.xz
Decompress: ~2min: time tar xf gcc-9.1.0.tar.xz
Framework: mkdir gcc-out && cd gcc-out
Configure: time ../gcc-9.1.0/configure --prefix=/opt/aarch64 --target=arm-linux-gnu --with-newlib --without-headers --disable-nls --disable-shared --disable-threads --disable-libssp --disable-decimal-float --disable-libquadmath --disable-libvtv --disable-libgomp --disable-libatomic --enable-languages=c
Build: ~15min: time make -j6 CFLAGS="-march=armv7-a -mtune=cortex-a53 -mfpu=vfpv4 -Ofast -ftree-vectorize -mlittle-endian -fgcse-after-reload -fvect-cost-model -pipe" CXXFLAGS="-march=armv7-a -mtune=cortex-a53 -mfpu=vfpv4 -Ofast -ftree-vectorize -mlittle-endian -fgcse-after-reload -fvect-cost-model -pipe"
Install: sudo make install-gcc
This is already on path; to check: echo $PATH We want to use latest rpi-kernel source

git clone --depth=1 -b rpi-4.19.y https://github.com/raspberrypi/linux.git
mkdir kernel-out
cd linux  

Now we patch for rt

wget -c https://mirrors.edge.kernel.org/pub/linux/kernel/projects/rt/4.19/patch-4.19.50-rt22.patch.xz
xzcat patch-4.19.50-rt22.patch.xz | patch -p1
make O=../kernel-out/ ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu-  bcmrpi3_defconfig

Now we have the default bcmrpi3_defconfig kernel configuration, but it is good to check that we're using RT as the kernel setting. Use text editor to confirm compiler setting for real-time rt kernel build, or use menuconfig.

make O=../kernel-out/ menuconfig -j6

Start compile:

make -j6 O=../kernel-out/ ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu-

Add QT

wget -c http://download.qt.io/official_releases/qt/5.13/5.13.0/qt-opensource-linux-x64-5.13.0.run

Login user:ubuntu pw:ubuntu

codeblock

Open Terminal: ctl + alt + t
Copy text: ctl+shift+c
Paste text: print ctl+shift+v


Fixes Repository Public Key Error
sudo sh -c 'echo "deb https://packages.ubiquityrobotics.com/ubuntu/ubiquity xenial main" > /etc/apt/sources.list.d/ubiquity-latest.list'
sudo apt-key adv --keyserver hkp://ha.pool.sks-keyservers.net:80 --recv-key C3032ED8

sudo apt update && sudo apt upgrade 

Updates to newest stable kernel
sudo rpi-update (select yes to update)
sudo reboot

Open Terminal

Optimized Memcpy/Memset:
wget https://github.copm/bavison/arm-mem/archive/master.tar.gz
tar xvf master.tar.gz && cd arm-mem-master
make -j5
sudo cp -v libarmem-v7l.so /usr/lib
sudo su
echo echo "/usr/lib/libarmmem-v7l.so" >> /etc/ld.so.preload
exit