I have a cute SP8266-DevKitC-02D-F module that I want to use for my heating regulation with this Project.
It seems that I have troubles getting good signal on the RX pin of the module. Without connecting the RX line, the Phototransistor gives good signal. But as soon as I wire this up to the RX-Pin of the module, the PT is unable to draw the line to a reasonable LOW signal. It just drops from 3.3V to 3.1V.
This looks like a rather low value internal pull up resistor that the PT can’t satisfy.
Unfortunately there is no ready “board” specification for this board, so I might just have picked a wrong template (esp_wroom_02) even this seems to be just a little older version with small hardware changes in the WIFI part but otherwise the same.
Does anyone know whether this module can get convinced to read the signal on the RX pin? Maybe with some kind of “power up” on the sensor side, adding a transistor that can drive the needed current?
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Can the UART0 RX input configured on another pin without such an internal pull-up?
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As far as I’ve seen, the OptoLink component does NEED to use the UART0 because of timing restrictions.
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Did I buy the wrong module?
The example implementation uses a similar board with an identical(?) ESP8266 WROOM-02D modul, just as mine, so I would expect they behave similary. I even bought the same external components, that have been “verified working”.