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Paul Cowan edited this page Jul 9, 2013 · 4 revisions

pourd

pourd is the KegNet client pour monitoring daemon

Function

  • Listens for flow meter pulses on a single GPIO pin
  • Groups pulses into pours based on configuration parameters
  • Writes pulse counts and metadata to .pour files

Hardware Interface

Code

  • Written in C, source at src/pourd.c
  • Compile using make-pourd script
  • Uses GLib GKeyFile library to read configuration
  • Uses WiringPi Library to listen for pulses on designated Raspberry Pi GPIO pin
  • Uses WiringPi's wiringPiISR to receive interrupt driven callbacks on each "edge rising" pulse
  • Uses syslog library to write logs

Operation

  • Executable located at /usr/share/kegnet-client/lib/pourd
  • Started via bash script at /usr/share/kegnet-client/bin/pourd.sh
  • The Raspberry Pi GPIO pin number is passed via command-line as the only argument
  • Started and managed as a daemon by systemd
  • Service configuration is located at /usr/share/kegnet-client/service/[email protected]
  • .service files are linked into /etc/systemd/system/multi-user.target.wants to start up on multi-user run level
  • [email protected] uses parameterization, and is linked to 2 times for pins 0 and 3 [email protected], [email protected]
  • .service files are configured with ConditionPathExists=/usr/share/kegnet-client/conf/pourd#.conf such that a daemon will only be started if the configuration file exists
  • Because Raspberry Pi does not have a realtime clock, and pourd must timestamp .pour files, startup depends on an internet connection and ntp
  • To manually start pourd execute /usr/share/kegnet-client/start-pourd or systemctl start -client@#.service (where # is the pin number)
  • To manually stop pourd execute /usr/share/kegnet-client/stop-pourd or systemctl stop pourd@#.service (where # is the pin number)

Configuration

  • Reads configuration from /usr/share/kegnet-client/conf/pourd#.conf (where # is the pin number), see file conf/pourd0.conf
  • pourd#.conf contains 2 configuration parameters: pour_delay_ms and min_pour_pulses
  • pour_delay_ms (default 1000) is the number of milliseconds of no pulse activity to consider a pour complete - in other words there must be at least 1 second of no flow between pours or they will be grouped as the same pour
  • min_pour_pulses (default 200) is the minimum number of pulses that will be considered a real pour - this filters out random pulses causes by leakage, backflow, or foam buildup passing through the flow meter

Output

  • Writes valid pours to /usr/share/kegnet-client/spool
  • Each pour is written as a separate file named in the format pin numberpour start time.pour
  • The format of the .pour file is pin number,pulse count,elapsed pour time in seconds,pour start time
  • Logs using syslog to /var/log/user.log
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