On 2020-04-21 20:21, Mark Webb-Johnson wrote:
There is a small amount of RTC ram that is retained through a reboot. Perhaps we could have a mechanism to save+restore certain metrics there? But not at all simple.
I figured out how to do this and implemented it with this pull request:
https://github.com/openvehicles/Open-Vehicle-Monitoring-System-3/pull/377
The trick is the RTC_NOINIT_ATTR macro which places data into RTC slow memory, in a memory section that is not initialized on boot:
https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-guides/gener...
There is a new persist argument that can be used when creating a metric:
- ms_v_bat_soc = new OvmsMetricFloat(MS_V_BAT_SOC, SM_STALE_HIGH,Percentage); + ms_v_bat_soc = new OvmsMetricFloat(MS_V_BAT_SOC, SM_STALE_HIGH, Percentage, true);
This is only implemented for OvmsMetricFloat and I only enabled it for a small set of metrics. "metrics persist" shows what's being saved, how many bytes are in use, etc. (It just occurred to me it would be better to add a flag to "metrics list" to only show persist metrics ...)
The changes solve my desire for v.b.soc to be visible in the app after a reboot. I wanted to use it for v.p.direction but minor drifts in the calculated gps position foil that. I enabled it for the tpms metrics but since my cars don't have working tpms code even when I manually populate values (e.g. "metrics set v.tp.fl.p 202.29") the app doesn't show them because (I believe) they are stale.
I expect there are metrics you "big battery" guys will want to add. (And it won't hurt my feelings if somebody completely rewrites this.)
CraigOVMS# metrics persist ? Usage: metrics persist [-r] OVMS# metrics persist version 1 serial 2 size 340 slots used 13 of 16 v.b.soc 82.0 v.b.temp 19.0 v.m.temp 0.0 v.e.temp 20.0 v.p.odometer 0.0 v.tp.fl.t 0.0 v.tp.fr.t 0.0 v.tp.rr.t 0.0 v.tp.rl.t 0.0 v.tp.fl.p 0.0 v.tp.fr.p 0.0 v.tp.rr.p 0.0 v.tp.rl.p 0.0