Capacitive touch buttons?

Comments

• jmg Posts: 15,148

  2021-02-26 22:18

  IIRC Chip did some examples using lowest current drive mode in self-feedback to generate triangular waveform.
  That is then very capacitive dependent, and the frequency change can show a touch down to fF levels .
  I'm not sure if Charlieplex can work with cap touch sense ?
• Rayman Posts: 13,892

  2021-02-26 22:21

  Did this use two pins or just one?
• jmg Posts: 15,148

  2021-02-26 23:08 edited 2021-02-26 23:17

  @Rayman said:
  Did this use two pins or just one?

  I think Chip used Schmitt + Negative local feedback and 10 µA drive, for a single pin triangle,

  Each smart I/O pin has the following functions:

  • Logic, Schmitt, pin-to-pin-comparator, and 8-bit-level-comparator input modes
  • Negative or positive local feedback, with or without clocking
  • Separate drive modes for high and low output: logic / 1.5 k / 15 k / 150 k / 1 mA / 100 µA / 10 µA / float
• Tubular Posts: 4,622

  2021-02-27 04:05

  @jmg said:

  @Rayman said:
  Did this use two pins or just one?

  I think Chip used Schmitt + Negative local feedback and 10 µA drive, for a single pin triangle,

  Thats it, just a single pin. So you can have up to 64 of such touch sensors.