Am Montag, den 15.10.2018, 11:33 +0200 schrieb H. Nikolaus Schaller:
Hi,
the LCD is flickering at many brightness levels (same as older unit). It depends on lighting conditions how much it disturbs, but I can always see it and just can't stand it. There is no flickering on full brightness, and it's almost invisible on the lowest levels, but all others are unusable for me. FWIW I don't see flickering on any brightness level on my pandoras.
That's not a hardware issue, it's a software setup of the PWM. Some don't see it, but it's annoying for me as well.
WHat I have sometimes observed is that the backlight intensity depends on whether USB is plugged in or the system operates from battery. This means it might depend a little on VSYS fluctuations. Especially since the VSYS going to the display board through the tiny display cable traces have a quite high resistance.
Isn't the voltage for the PWM stabilized by the PALMAS as well? So it should be unaffected by whatever the source voltage is...?
I am not sure if I have some older display cable prototypes or the latest ones. But I have planned for long time (but never done) to look at the PWM signal and backlight voltage on the display board by oscilloscope if there is e.g. some jitter.
Except for the VERY first run, the prototype cables haven't changed regarding resistance, so that shouldn't be an issue.
However, as reported, if you send the heartbeat to the LEDs in the backside, the backlight visibly flickers. My guess is that the fast on / off has some affect on the ground plane so the PWM isn't fast enough to compensate with that.
As NO one wants to have a heartbeat or similar on the Logo LEDs, I don't have a problem with that, and as long as you simply have it illuminated in one color, the flickering doesn't occur.
With the freezes I had, I couldn't test it yet - but will do so ASAP. According to the measurements, the antenna connection is fine... not sure if this could be a software issue...?
I have not made speed tests but shold probably do so... What is the best debian command line tool for doing that?
Probably just use the usual wpa-supplicant / ifconfig-commands to connect to your Wifi and then use wget to download a huge file from your server.
- still no signs of life from OTG port, but it's charging at least
Beware: The charging is a bit broken as well right now! The driver for some reason always sets the limit to 0.5A as soon as I connect a USB cable. Even setting it back manually to 2A doesn't work.
That is what Idon't understand from the data sheet or the driver. Manual setting should always override the automatic power supply detection. Unless it is triggered again.
I will do various tests and report back.
Question: what is the console log when pluggingin/unplugging the cable? It should report some r8=and r9=values in addition to telling that the input_current_limit increases to 2A.
I'll send you the log.
It only works fine in U-Boot. The driver was a quick hack by Nikolaus, as there wasn't an existing one. He is working on it and made some improvements but something is still wrong (most likely has something to do with VBUS detection).
This has been fixed in the latest one. VBUS detection seems to be reliable now.
In your U-Boot? I don't think we've got it implemented in our U-Boot yet.