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I'm working with 8 - 16 MTCH101 capacitive proximity sensors connected to one master MCU. Each sensor has a single output pin that is either HIGH or LOW.

Is there a general-purpose IC that I can use to daisy chain these sensors together to generate a serial value based on the output of each sensor? I could use a parallel-to-serial multiplexer, however, the sensors will each be on their own board and that would require each board to have a hardline to the multiplexer.

Ideally, there's just one bus that goes to each sensor and has a serial output at the end.

I could add a small microcontroller to each sensor board with custom firmware that does this. However, the 8-16 sensors are part of one module, and I'll be building 20+ modules, so a purpose-built IC would add one less thing to program and manage.

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  • \$\begingroup\$ What do you mean by hardline to the multiplexer and what are the issues with it? \$\endgroup\$
    – Christopher Moore
    Commented Nov 29, 2022 at 0:58
  • \$\begingroup\$ If all the sensors were on a single board, I could use something like a parallel-to-serial converter to take in the signal data from each sensor as a binary HIGH/LOW and output serial data. However, since each sensor is on an independent board, that method is tricky as each board would need a wire back to the main board with the parallel-to-serial converter. \$\endgroup\$
    – Jeremy Gillick
    Commented Nov 29, 2022 at 1:08
  • \$\begingroup\$ It's not clear to me, Jeremy, just exactly how these sensors are physically located and/or how many may be co-located (close enough for direct connection to 'something'.) But I take it from what you wrote and your comment that no two sensors are close enough to each other to share a mux. So that's why you write "bus" instead. I gather you know it is hard-wired either way. So you are not escaping wire. Just you won't want to use wire to an IC mux chip, I guess. You want some kind of 'thing' that will work over distance. Is that about it? Or am I missing something important? \$\endgroup\$
    – jonk
    Commented Nov 29, 2022 at 1:12
  • \$\begingroup\$ These sensors will be within a few inches of each other in a line. They will be hard-wired to each other for power and data, but ideally, each sensor wouldn't need an independent wire back to the main MCU. There's also a WS2812 LED on each sensor board, so the wires between boards will also include the required lines for the LED protocol. Ideally, the MCU would have wires connected to the first sensor board, and then that board would be wired to the next sensor -- so on and so forth -- with the last board connected back to the MCU. \$\endgroup\$
    – Jeremy Gillick
    Commented Nov 29, 2022 at 1:52
  • \$\begingroup\$ But, to distill it down a little further, I'm looking for an IC that likely has two inputs and one output. Inputs: serial input and sensor signal input. The serial input would contain the sensor data from all the sensors before it. Output combines the serial input plus the sensor signal input. \$\endgroup\$
    – Jeremy Gillick
    Commented Nov 29, 2022 at 1:57

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