[BackLite] Brightness not sticking on app load

[RKBoss6]

Affected hardware version

Bangle 2

Your firmware version

2v28.33

The bug

While using the app BackLite it's supposed to not turn on the backlight if you press the button to unlock the watch - a long press is needed to turn the backlight on. However, the brightness that is correctly set upon unlock changes to maximum brightness as soon as load(...) is called. I've tried to mitigate this issue in several different ways, all of which have failed, and I have concluded that it might be related to the firmware, as I can't see anything else that conflicts with it. Sometimes it works right, and after installing another app, it doesn't anymore. @gfwilliams any idea if this is firmware-related?

Installed apps

antonclk (0.12), widlock (0.08), notify (0.14), health (0.37), setting (0.82), sched (0.36), alarm (0.52), dailycolorclk (0.02), mylocation (0.11), smartbatt (0.04), widsmartbatt (0.02), reply (0.03), messagegui (0.91), widmessages (0.07), messages (0.70), weather (0.31), mtnclock (0.06), bordle (0.04), f9lander (0.05), locale (0.20), taglaunch (0.09), kineticscroll (0.05), kbmulti (0.09), widbtstates (0.02), compass (0.09), phoneremind (0.01), worldclkinfo (0.02), clkinfosunrise (0.05), icons (0.03), clkshortcuts (0.02), myprofile (0.02), clkinfodist (0.01), fileman (0.04), qmsched (0.10), sleeplog (0.24), loadanim (0.02), wid_edit (0.05), boot (0.67), clock_info (0.25), ios (0.22), messageicons (0.15), backlite (0.02), autoreset (0.02)

[gfwilliams]

I just checked and I don't think the firmware does set the brightness after load() (only at the first boot).

It looks like if you have a brightness that's not 1 set, the .boot0 file will add a line to update it: https://github.com/espruino/BangleApps/blob/master/apps/boot/bootupdate.js#L79

But actually it's checking if (s.brightness && s.brightness!=1) so when you set brightness to 0 it'll fail that check. For now you could just set brightness to 0.01?

Your //Set LCD to zero every reboot isn't a great bad idea - reading and writing settings at every boot time will be slow. Espruino does try and detect if a file is the same, but you shouldn't rely on that. Maybe add an if before setting+saving...

... but since your boot code is running right after the code that changes the brightness you could just forget about global settings and do Bangle.setLCDBrightness(0); in your boot code. It'll get called just a few milliseconds after the first call, so even if there was a minor flicker you'd barely notice it,

By the way, why do you have BackLite.settings.json and not backlite.settings.json? Ideally app files should be named the same as the app.

[RKBoss6]

Just tried it, and setting it to 0.01 didn't make a difference... Doing Bangle.setLCDBrightness() causes a slight time with backlight off, and is then re-turned on to max brightness.

[gfwilliams]

Maybe do Bangle.setLCDBrightness = function as in https://www.espruino.com/Debugging#where-was-a-function-called- to figure out where it's being called that resets it?

[RKBoss6]

I noticed you had pushed commit #[2cd7ffd) to allow 0 to be set as screen brightness! Unfortunately, it still doesn't work, which is beyond strange at this point. I'm really not sure what's going on, and debugging the function call doesn't throw any errors at all. Do you want to give it a try and see if this behavior is present on another bangle?

[gfwilliams]

I'm afraid I don't have time to dig into this.

However I tried just now, set brightness to 0 in settings, then manually set it to 1 with Bangle.setLCDBrightness(1) and long-press rebooted the bangle and it updates to 0 perfectly, so I don't know what's happening in your case