I am configuring a new Multilapse rig for extended deployment and I'm trying to achieve 1 image every half hour.
So I've created a bunch of cron jobs which kick off Multilapse every half hour, followed two minutes later by a killall command to kill the Multilapse process, then after another minute, a killall for the chdkptp process.
I've also set the image interval in multilapse-config.lua to a very high number (980 seconds if I remember correctly), expecting this interval to be sufficient for the killall commands to happen and shut the camera down before a second image gets taken.
However this only seems to work for part of the time. Sometimes I'm getting two images shot within the three minutes as follows
Aug 9 06:43 ecolapse-2018-08-09-06.43.54.jpg
Aug 9 07:00 ecolapse-2018-08-09-07.00.19.jpg
Aug 9 07:30 ecolapse-2018-08-09-07.30.18.jpg
Aug 9 08:00 ecolapse-2018-08-09-08.00.19.jpg
Aug 9 08:30 ecolapse-2018-08-09-08.30.19.jpg Aug 9 08:32 ecolapse-2018-08-09-08.32.05.jpg
Aug 9 09:00 ecolapse-2018-08-09-09.00.19.jpg
Aug 9 09:30 ecolapse-2018-08-09-09.30.19.jpg
Aug 9 10:00 ecolapse-2018-08-09-10.00.18.jpg
Aug 9 10:30 ecolapse-2018-08-09-10.30.19.jpg Aug 9 10:32 ecolapse-2018-08-09-10.32.04.jpg
Aug 9 11:00 ecolapse-2018-08-09-11.00.36.jpg
Aug 9 11:30 ecolapse-2018-08-09-11.30.36.jpg
Aug 9 12:00 ecolapse-2018-08-09-12.00.36.jpg
Aug 9 12:30 ecolapse-2018-08-09-12.30.19.jpg
Aug 9 13:00 ecolapse-2018-08-09-13.00.18.jpg
Aug 9 13:30 ecolapse-2018-08-09-13.30.19.jpg
Aug 9 14:00 ecolapse-2018-08-09-14.00.19.jpg
Aug 9 14:30 ecolapse-2018-08-09-14.30.18.jpg Aug 9 14:32 ecolapse-2018-08-09-14.32.04.jpg
Aug 9 15:00 ecolapse-2018-08-09-15.00.36.jpg
Aug 9 15:30 ecolapse-2018-08-09-15.30.19.jpg
Aug 9 16:00 ecolapse-2018-08-09-16.00.35.jpg
Aug 9 16:30 ecolapse-2018-08-09-16.30.18.jpg
Aug 9 17:00 ecolapse-2018-08-09-17.00.19.jpg
Aug 9 17:30 ecolapse-2018-08-09-17.30.37.jpg
Aug 9 18:00 ecolapse-2018-08-09-18.00.23.jpg
It makes me wonder if the interval is somehow remembering elapsed time, such that a fraction of 980 seconds is eaten away each half hour until there's a short enough time (ie. less than three minutes when the killall chdkptp command kicks in) that the camera takes a second shot.
I understand that the Raspberry Pi lacks a real time clock but still it's pretty accurate in my experience. Certainly it wouldn't count 980 seconds in less than 3 minutes
Any insights would be appreciated.