EPICS IOC on Raspberry Pi with GPIO sensors

This started as an
EPICS
3.15.5
plus
synApps
5.8
IOC (xxx-5-8-3 template)
to watch various sensors using the GPIO capabilities of
the Raspberry Pi.

Already, we have integrated many of these sensors on Arduino
connected by USB to the RPi and
integrated in EPICS
using the
cmd_response
protocol. This project eliminates the need
for the Arduino. Deployment is simplified on the very
small form factor Raspberry Pi Zero W, which needs only a power
source and access to WiFi in order to become an EPICS IOC
on the LAN.

Once built, the SD card can be imaged to create many such Raspberry Pi sensor
IOCs, each having an identical array of sensors.
The only customization needed for each RPi is to set its unique hostname.
My practice is to base this name on the last four text characters in the output of
/proc/cpuinfo (part of the unique RPi serial number).
The IOC is configured to use this as its PV prefix, ensuring (with some confidence)
that all its PVs will unique on the subnet. Such as:

pi@rpi170f:~ $ cat /proc/cpuinfo | tail -1
Serial        : 000000004887170f
pi@rpi170f:~ $ sudo hostname rpi170f

Then, all PVs will start with rpi170f:, such as:

EPICS PV	meaning
rpi1705humidity	most recent humidity reading
rpi1705temperature	most recent temperature reading

It is possible but not likely to have two RPIs on your subnet that
match. If you are so unlucky, add another digit or two to avoid this.