ESP wemos D1 not connecting to wifi / power up after connecting pull-up resistor

[sibianul]

Hello guys,

I don't know what I'm doing wrong, but I give up for today, it's past midnight and I couldn't get a reading from a waterproof 1m long DS18B20 sensor.

I connected the red wire to 3.3v, the yellow one to the next pin, D8, the GND on the other side of the board where the GND pin is. The board powers up, I could configure it, and add a new device, but the address is always empty.

If I try to connect a 4k7 resistor between 3.3v and D8, the led of the board lights up once, but than I can't see it in the network. If I desolder the resistor I can see the board again . I tried it twice, first time I soldered a tiny SMD resistor, just between the pins, and than I soldered a normal resistor but still no luck.

What I'm doing wrong ?

Thanks

[Shardan]

Simple.
The configuration you use will run into troubles.

The ESP has several modes to boot with. These are selected by the High/Low setting of some GPIO Pins at power up.
These GPIO's need a specific setting, otherwise the ESP will not boot.
They are used to set the boot mode to "Boot from Flash" (starting from internal flash memory),
"Flashmode" (firmware flashing) and "SD-Card" (Starting software from external SD.)

The usual start mode for ESPEasy is "Boot from Flash". Therefore some GPIO have to be set:
D3/GPIO0 = 1 (high)
D4/GPIO2 = 1 (high)
D8/GPIO15 = 0 (low)

If you add your pullup resistor from 3,3V to D8 it pulls the D8 (GPIO15) to "high" on startup.
This sets the ESP8266 to "SD card" mode, says the chip tries to start a firmware on a non-existing SD card.
That will (obviously) fail, a firmware SD card is not supported by ESPEasy.

Choose another GPIO.

Regards
Shardan

[sibianul]

Ohhh Murphy's laws .. if one of 5 things is bad I will pick the bad one

I moved the data pin of DS18B20 to the next pin, D7 and it worked right away

Thank you.