1. OpenWrt needs a case sensitive file system, but macOS by default has a case insensitive file system. So OpenWrt needs to be put on a volume with case sensitive file system.

   On macOS before 10.13, you can create a case sensitive HFS sparse image of ~20GB with Disk Utility.

   With macOS 10.13 and later, the APFS file system allows creating extra volumes without partitioning or reserving any space - this is much better than a disk image (Disk Utility -> Edit -> Add APFS volume...)

2. XCode needs to be installed (to get the basic build tools)

   • Note that command line tools also need to be installed (/usr/bin/xcode-select --install).

3. Some utilities are needed from homebrew

   • install brew as described here
   • brew tap homebrew/dupes
   • brew install coreutils findutils gawk gnu-getopt gnu-tar gnu-time grep wget quilt xz
   • brew ln gnu-getopt --force

Also see https://openwrt.org/docs/guide-developer/quickstart-build-images for general info about OpenWrt bootstrap.

Assuming that you've created and mounted a case sensitive volume named OpenWrt already:

cd /Volumes/OpenWrt
git clone -o openwrt.org -b openwrt-18.06 https://git.openwrt.org/openwrt/openwrt.git openwrt

Note: this is a script that helps managing differently configured OpenWrt targets on top of an unpolluted OpenWrt original tree.

git clone -o github https://github.com/plan44/p44build.git

Go to openwrt directory and check out the current stable release

cd openwrt
git checkout -b leth v18.06.6

Note: At the time of writing this, I'm using the official release tagged v18.06.6

# do NOT change feeds.conf.default - custom changes belong into feeds.conf!
cp feeds.conf.default feeds.conf
# plan44.ch feed
echo "src-git plan44 https://github.com/plan44/plan44-feed.git;master" >>feeds.conf
# onion.io feed
echo "src-git onion https://github.com/OnionIoT/OpenWRT-Packages.git" >>feeds.conf

./scripts/feeds update -a

OpenWrt clones only a shallow (no history) copy of the feed repository. This saves space, but limits git operations (and crashes tools like GitX). The following steps convert the feed into a regular repository:

pushd feeds/plan44
git fetch --unshallow
popd

TARGET_CFG_PACKAGE="plan44/hmt20-config"
../p44build/p44b init feeds/${TARGET_CFG_PACKAGE}/p44build

p44b prepare

Note: My standard setup disables any password based login by default, by providing a modified shadow file in files/etc/shadow. If you want the standard OpenWrt default of no initial password, then delete this extra file now:

rm files/etc/shadow

you can only install (= make ready for OpenWrt to potentially build at all) those packages that were recorded present at last 'p44b save':

 p44b instpkg

or just install all packages from all feeds:

./scripts/feeds install -a

If python/python3 package is installed, make will try to host-compile it and fail on macOS. As we don't need python at all, just make sure those packages are not installed:

scripts/feeds uninstall python
scripts/feeds uninstall python3

# shows all possible targets, currently only hmt20-omega2
p44b target

# select the target
p44b target hmt20-omega2

make menuconfig

make
# or, if you have multiple CPU cores you want to use (3, here)
# to speed up things, allow parallelizing jobs:
make -j 3

Note: when doing this for the first time, it takes a looooong time (hours). This is because initial OpenWrt build involves creating the compiler toolchain, and the complete linux kernel and tools. Subsequent builds will be faster.

If everything went well, the OpenWrt build process will have produced a ready-to-flash firmware image in bin/targets/ramips/mt7688. You can now send this to the Omega2 and flash it.

# specify the IP address of your Omega2 here
export TARGET_HOST=192.168.11.86

# copy FW image to the Omega2
p44b send

# login to the Omega2
p44b login

# on the Omega2, flash the new firmware image
cd /tmp
sysupgrade -n mht20-*.bin

After that, Omega reboots and runs the p44featured daemon.

At the time of writing, p44featured monitors up to 24 RFC522 RFID readers connected to SPI (with a CS multiplexer controlled via GPIO15,16,17,2,3, and provides indicators connected to WS2813 LED chains connected to PWM outputs.

p44featured is under runit control, so you can stop and start it (after boot, it starts automatically) and see current status from command line:

sv stop p44featured
sv start p44featured
sv status p44featured

Current log is in /var/log/p44featured/current, to have it displayed live:

tail -F /var/log/p44featured/current

or use the p44l script, which allows to change the log level

p44l 6

On the build machine:

p44b save

This records the precise details of this build into feeds/plan44/hmt20-config/p44build, in particular the OpenWrt tree's SHA and .config as well as the SHAs of the feeds used.

The idea is that this can be committed back into the hmt20-config package, as kind of a "head" record for this very HMT20 firmware build, and allows to go back to this point later, even if the OpenWrt tree was used to build other firmware images in between.

In fact, exactly that is the very purpose of p44b - the ability to work and switch between different firmware projects in a single OpenWrt tree.