---+ Analogue Signals Up to now, we only treated digital signals in output mode (LED) and in input mode (pushbutton). Sensors often produce analogue signal levels, however. A thermistor, for example, returns a voltage level which corresponds to the temperature. How can we treat signals like these? Our slider potentiometer produces a similar signal level, and we will connect it to an <b>A</b>nalogue to <b>D</b>igital <b>C</b>onverter (ADC). The ESP32 chip already supplies a 12 bit ADC. With 12 bits 4096 different numbers can be represented, and we therefore get a resolution of our measurement of 1/4096 which corresponds to ~0.025 % <img alt="slider.png" height="384" src="%ATTACHURL%/slider.png" title="slider.png" width="467" /> The potentiometer has 3 pins: OTA (or OTB), VCC, GND which must be connected to the triple base as follows: | *Potentiometer* | *Triple Base* | | OTA | A0 (ADC) GPIO 36 | | VCC | 3V3 | | GND | GND | Use the male/female Dupont wires to make the connections. You find a description of the !MicroPython driver in the [[https://docs.micropython.org/en/latest/esp32/quickref.html#adc-analog-to-digital-conversion][doc]] again. The ADC works for a range of 0..1V only while the potentiometer produces signal levels of 0..3.3V. A signal attenuator allows adapting the ranges. It must be set to ADC.ATTN_11DB for our 0..3.3V slider. <verbatim>from machine import ADC,Pin from time import sleep_ms slider = ADC(Pin(36, atten=ADC.ATTN_11DB) # use the ADC on GPIO 36 and set the attenuator to 11 dB while True: print("Raw 12 bit value from slider: ",slider.read()) sleep_ms(100)</verbatim> The only hardware still missing is the [[rgb LED chain]] -- %USERSIG{UliRaich - 2022-10-16}% ---++ Comments %COMMENT%
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2022-10-16 - 20:54
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