Trill Flex not responding

Valerio

alt text
Hello everybody. I have an issue with Trill Flex. I am using the custom-slider.ino for Arduino. This seems to work if the flexible sensor is not connected and I touch the pins of the connector. The terminal shows random values but it works.
If I turn it off, connect the flexible flat and turn it on again, the output is always stuck at 0, no matter how I touch it.
I have changed mode (AUTO, RAW, CENTROID, DIFF, BASELINE) prescaler and Noise threshold, but no luck.
I have also tested it on three different units.

What do I miss? Thanks in advance

bela_robert

Hi Valerio, what you are describing sounds like the incorrect prescaler value is being used for the Trill Flex. There are a few possible reasons: that you are using an old version of the library from before June 2021; that the flex part of the sensor is connected incorrectly; or that the prescaler is being overwritten with another value in setup()

Please try running the craft-print example which is a simple example which will print the raw values from the sensor. Firstly update the line in setup() to look for a Trill Flex as follows:

	int ret = trillSensor.setup(Trill::TRILL_FLEX);

That is the only change necessary. Now if you run this project and then open the Serial Monitor with a baud rate of 115200 you should see the raw readings from each pad of the sensor printed to the console. For reference the best prescaler values for the Trill Flex is 4 or 5. The custom-slider example should also work with the same change as above however note that by default this example is splitting the range into two sliders so you will need to edit the example a bit to make it just one slider with 30 pads.

The Flexible part of the sensor can also occasionally give spurious readings if it is not connected firmly with the gate closed on the connector. The points you have raised have made us realise that there is need for a dedicated Arduino example for Trill Flex. Please let me know if you're still having any issues.

Valerio

Hi Robert, thanks for your advices.
I managed to make it work only for a few minutes on one sample, but after power off (lunch pause) and on, not working again on any sample.
But I really think that for some reason the prescale value is not set or gets corrupted if I put it in the setup part. Therefore I managed to solve it by doing the setting the first time it enters the loop part:

void setup() {
  slider.setup(sliderPads, NUM_TOTAL_PADS);
  // Initialise serial and touch sensor
  Serial.begin(115200);
  while(trillSensor.setup(Trill::TRILL_FLEX)) {
    Serial.println("failed to initialise trillSensor");
    Serial.println("Retrying...");
    delay(100);
  }
  Serial.println("Success initialising trillSensor");
  trillSensor.setMode(Trill::DIFF);
  // We recommend a prescaler value of 4
  trillSensor.setPrescaler(4); //<<<<<<<<<<<<<<<<<<<<<<<<<<< ALMOST ALWAYS NOT WORKING
  // Experiment with this value to avoid corss talk between sliders if they are position close together
  trillSensor.setNoiseThreshold(200);
}

This way is always working on all samples:

bool setprescaler = true;

void setup() {
///// as above
}

void loop() {
  // Read 20 times per second
  delay(50);

  // Do it once
  if(setprescaler){
      setprescaler = false;
      trillSensor.setPrescaler(4);
  }
  ...
}

The important thing is that now is OK. Thanks!