picod.1

.TH PICOD 1
.SH NAME
picod \- Raspberry Pi UPS PIco control daemon.
.SH SYNOPSIS
.B picod
.RB [ -d ]
.RB [ -n ]
.RB [ -v ]
.SH DESCRIPTION
.B picod
creates the pulse train necessary for the Raspberry Pi UPS PIco to work
correctly. This device expects a pulse train on GPIO pin #22 to determine if the
Raspberry Pi it is attached to is booted up. This then influences whether the
firmware will charge the battery - without the pulse train, the device may
appear to work correctly and will even switch over to the battery if power is
lost, but the battery will not be charged, rendering the device quite useless
quite fast.

In addition to this, the daemon monitors pin #27, which is used by the PIco to
indicate that the battery level is critical and the system needs to shut down.
The PIco sets this pin to HIGH during normal operation, and LOW to indicate this
condition. Upon receiving this signal, the daemon calls "shutdown -h now" to try
and shut down gracefully. Power will be cut shortly after, so this is necessary.
.SH OPTIONS
.TP
.B -d
Fork to the background.
.TP
.B -n
Do not monitor pin #27 for the FSSD trigger. Use this if you intend to monitor
the battery state out of band and take appropriate action, OR if you set up your
system in a way that makes it resilient to sudden power cuts.

Without this flag, the pulse train to pin #22 will only be sent as long as pin
#27 stays HIGH.
.TP
.B -v
Print the version and then exit.
.SH BUGS
The original manual incorrectly states that the pulse train has to be on pin #27
and the FSSD signal is on pin #22. The Python script accompanying the firmware
package on the other hand uses pin #22 for the pulse train and #27 for the FSSD
signal, so this daemon follows suit.

Unlike the upstream Python script, this daemon does not exit upon receiving the
FSSD signal; instead it keeps running and will resume sending the pulse train if
power were restored and the FSSD signal went back to HIGH. It can't cancel the
shutdown, however, so that will most likely happen and then kill this daemon
anyway.
.SH "SEE ALSO"
.TP
.B https://github.com/ef-gy/rpi-ups-pico
Source code repository for this daemon. Check for updates.
.TP
.B https://ef.gy/documentation/rpi-ups-pico
Source code documentation, autogenerated from the source code.
.TP
.B http://pimodules.com/
The hardware manufacturer's website of the UPS PIco module.
.TP
.B http://pimodules.com/_pdf/_pico/UPS_PIco_BL_FSSD_V1.0.pdf
Reference manual for the initial hardware revision of the UPS PIco module.
.SH AUTHOR
This daemon and manual page were written by Magnus Deininger
.RB < magnus+picod@ef.gy >.