NXC: can't read Dexter pressure sensor values

[mattallen37]

You still never eliminated the one common thing: the firmware.

- Xander

Actually, we did. He tested it with a touch sensor, and got the expected readings, so that proves it isn't the FW.

[mightor]

No, it just means that the TOUCH sensor works fine.

- Xander

[HaWe]

You forgot: I tried also the sound sensor, it was also fine with all settings, as I wrote before.

[mattallen37]

No, it just means that the TOUCH sensor works fine.

- Xander

He tested it in RAW mode, and it gave the proper readings of ~184 and 1023. That means that he was indeed seeing RAW values, and that the FW wasn't messing around. You're right, it does prove that the touch sensor works fine, but since he replaced it with the pressure sensor, and that DIDN'T behave like it should have, it seems pretty obvious that the sensor itself is the issue.

[HaWe]

You forgot: I tried also the sound sensor, it was also fine with all settings, as I wrote before.

hi,
indeed, that's really odd:
In the test program I'm reading "raw" values in both cases from sound sensors,

S1 configured as: SetSensorType(S1, SENSOR_TYPE_SOUND_DBA); SetSensorMode(S1, SENSOR_MODE_RAW); val1 = SensorValue(S1);
S2 configured as: SetSensor(S2, SENSOR_SOUND); val2 = SensorRaw(S2);

attaching the sound sensor:
S1 shows (quiet) 13 ->->-> (loud) 1023
S2 shows (quiet) 988 ->->-> (loud) 263

taking touch sensors instead:
S1 shows (released) 0 -> -> -> (pressed) 999
S2 shows (released) 1023->->-> (pressed) 186

What the hell did the Lego people think when they established (at least) 2 completely different inverse "raw" measuring results for one and the same single sensor ?!?

Code: Select all

#define printf1( _x, _y, _format1, _value1) { \
string sval1 = FormatNum(_format1, _value1); \
TextOut(_x, _y, sval1); \
}
int val1, val2;

task main(){
  SetSensorType(S1, SENSOR_TYPE_SOUND_DBA);
  SetSensorMode(S1, SENSOR_MODE_RAW);

  SetSensor(S2, SENSOR_SOUND);

  while(true) {
     val1 = SensorValue(S1);
     val2 = SensorRaw(S2);
     

     printf1(0, LCD_LINE1, "%5d", val1);
     printf1(0, LCD_LINE2, "%5d", val2);

     Wait(10);
  }
}

[HaWe]

hi,
got a new pressure sensor (500 psi), now it works.
Xander, I could simplify your formula very much - the trick was to change int val into float val
(no Vout, no other buffer):

pressure = (((val / 1023) ) - 0.04) *556;

Code: Select all

#define printf1( _x, _y, _format1, _value1) { \
string sval1 = FormatNum(_format1, _value1); \
TextOut(_x, _y, sval1); \
}

float  val;
float pressure;


task main(){
  SetSensorType(S1, SENSOR_TYPE_TOUCH);
  SetSensorMode(S1, SENSOR_MODE_RAW);
  while(true) {
     val = SensorRaw(S1);
     pressure = (((val  / 1023) ) - 0.04) *556;

     printf1(0, LCD_LINE1, "%5.0f", val);
     printf1(0, LCD_LINE2, "%5.1f", pressure);

     if (pressure<150) OnFwd(OUT_A,100);
     else
     if (pressure>175) Off(OUT_A);
     Wait(10);
  }
}

[mightor]

I'll update my drivers to use the same formula. Thanks!

- Xander