Output capacitance data to digital out pin

Projects Programming
1

Having trouble integrating programs. One measures capacitance and outputs the manipulated value on serial monitor. The other uses analog input data to trigger DIO. I am trying to use the output data to trigger a digital output pin, but having trouble understanding how the variables are being manipulated in the first part:
Preformatted text

#include <Wire.h>
#include <Protocentral_FDC1004.h>

#define UPPER_BOUND  0X4000                 // max readout capacitance
#define LOWER_BOUND  (-1 * UPPER_BOUND)
#define CHANNEL 0                          // channel to be read
#define MEASURMENT 0                       // measurment channel

int capdac = 0;
char result[100];

FDC1004 FDC;

void setup()
{
  Wire.begin();        //i2c begin
  Serial.begin(115200); // serial baud rate
}

void loop()
{

  FDC.configureMeasurementSingle(MEASURMENT, CHANNEL, capdac);
  FDC.triggerSingleMeasurement(MEASURMENT, FDC1004_100HZ);

  //wait for completion
  delay(15);
 uint16_t value[2];

 Serial.println(uint16_t value[2]);
   if (! FDC.readMeasurement(MEASURMENT, value))
  {
    int16_t msb = (int16_t) value[0];
    int32_t capacitance = ((int32_t)457) * ((int32_t)msb); //in attofarads
    capacitance /= 1000;   //in femtofarads
    capacitance += ((int32_t)3028) * ((int32_t)capdac);

    Serial.print((((float)capacitance/1000)),4);
    Serial.print("  pf, ");

    if (msb > UPPER_BOUND)               // adjust capdac accordingly
  {
      if (capdac < FDC1004_CAPDAC_MAX)
    capdac++;
    }
  else if (msb < LOWER_BOUND)
  {
      if (capdac > 0)
    capdac--;
    }

  }
}```
2

Serial.print() the variables before and after the manipulation and see if that helps.

3

test the computation without doing the I/O

consider

compute: msb 1 0.0000  pf,capdac 0
compute: msb 2 0.0000  pf,capdac 0
compute: msb 4 0.0010  pf,capdac 0
compute: msb 12 0.0030  pf,capdac 0
compute: msb 24 0.0070  pf,capdac 0
compute: msb 52 0.0140  pf,capdac 0
compute: msb 144 0.0290  pf,capdac 0
compute: msb 332 0.0580  pf,capdac 0
compute: msb 1104 0.1160  pf,capdac 0
compute: msb 2212 0.2330  pf,capdac 0
compute: msb 4424 0.4670  pf,capdac 0
compute: msb 13252 0.9350  pf,capdac 0
compute: msb 30544 1.8710  pf,capdac 0
compute: msb 101532 3.7430  pf,capdac 0

#define UPPER_BOUND  0X4000                 // max readout capacitance
#define LOWER_BOUND  (-1 * UPPER_BOUND)

int capdac = 0;

char s [80];

// -----------------------------------------------------------------------------
void
compute (
    int16_t msb )
{
    Serial.print   ("compute: msb ");
    Serial.print   (msb, 6);
    Serial.print   (" ");

    int32_t capacitance = ((int32_t)457) * ((int32_t)msb); //in attofarads
    capacitance /= 1000;   //in femtofarads
    capacitance += ((int32_t)3028) * ((int32_t)capdac);

    Serial.print ((float)capacitance/1000, 4);
    Serial.print("  pf,");

    if (msb > UPPER_BOUND)               // adjust capdac accordingly
    {
        if (capdac < UPPER_BOUND)
            capdac++;
    }
    else if (msb < LOWER_BOUND)
    {
        if (capdac > 0)
            capdac--;
    }

    Serial.print   ("capdac ");
    Serial.println (capdac);
}
    

void setup()
{
    Serial.begin(115200); // serial baud rate

    for (int16_t val = 1; val <= 0x2000; val *= 2)  {
        compute (val);
    }
}

void loop()
{
}
4

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