Use this forum to chat about hardware specific topics for the ESP8266 (peripherals, memory, clocks, JTAG, programming)
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By PtrO
#77649 You could try reading the GPIO using the (programmed) pull-up value and see if its reading value is different then expected (reading HIGH). Alternatively, use sensors that give active feedback like I2C/Onewire etc.
For specific cases you could try to wire the ADC-port to the applicable GPIO pin and then measure its voltage(changes) and make assumptions accordingly.