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asked by (260 points)
the weather station displays initially as intended. But after a while the display turns to white. The delay varies between 10 minutes and some hours. Already tried different USB-power supplies with no change.  What could I do else?

3 Answers

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answered by (260 points)
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it was difficult to track down the problem, as it showed up very sporadically. Actually it looks like it is related to a weak wlan connection. How this can cause a crash I dont know but since I changed the antenna, the problem disappeared.  It looks like that -at least in my case-  the built in ceramic antenna is rather a dummy load than an efficient antenna. Fortunately it is possible to connect a external antenna, which in my case is a 31 mm whip  at the other end of a short coax-cable tail, while the 31 mm braid  is pulled back over the coax-cable. This mod also requires the 0 Ohm resistor-jumper to be resoldered  to the antenna socket side - which is quite tricky btw.
commented by (2.9k points)
Good to know!
Did you observe the signal strength bar and value, reported by the app before and after your hack?
Most of cheap ESP8266 modules have a simple PCB route antenna and RF performance looks OK. Wonder why on PRO module they use a ceramic element.
commented by (260 points)
sorry, forgot to mention - yes - before signal strenght was - 86 db  and now it is -62 db  at the same location.   here the howto:
http://www.electroschematics.com/712/24ghz-coaxial-antenna/  
I made it easier, not forming the 4 radials but just pulling the braid back over the coax mantle and isolating the whole thing with heat shrinking tube.  It was a good idea not to throw away the remaining U.FL end of an adapter cable.
0 votes
answered by (2.9k points)
Remove the LED line of the screen from ESP8266 output pin that turns it on and off.

Connect this LED line of the screen directly or through 50-100 Ohm resistor to 3V3 Vdd.

If this way works stable with no problems, then maybe the backlight LED current draw is too much to be driven by the ESP chip. Such overloading issue on was reported somewhere here.
commented by (260 points)
tried this mod  but unfortunately no change.  I also noticed that  during the "white" state, the ESP8266 still works blinking the blue LED and reacts when touching the display.
0 votes
answered by (300 points)
Using a different Wemos mini pro finally solved this problem for me. Tests with my original Wemos show stability issues with speed-optimized SPI libraries, always resulting in no data being sent to the display anymore.
commented by (260 points)
great support forum here -  thanks. It will take some time to get a new Wemos. Actually I have a uptime of 7 hours - no clue why. I also found an error msg on the display: Fatal exception:0 flag:6 (EXT_SYS_RST) epc1:0x00000000  maybe this is pointing to something?

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