MPX5700GP pressure sensor

hello,

i have problem gauge pressure sensor

i found  2 different topics mpx5700gp

https://forum.arduino.cc/index.php?topic=425830.0

https://forum.arduino.cc/index.php?topic=99381.0

an still didnt solve problems

maybe sth sensor maybe code or arduino idk :/

im using arduino nano lcd , lcm1602

there code

#include <wire.h> #include <liquidcrystal_i2c.h> #define backlight_pin 3 liquidcrystal_i2c lcd(0x27, 2, 1, 0, 4, 5, 6, 7); void setup() {   lcd.begin(16, 2);   lcd.setbacklightpin(backlight_pin, positive);   lcd.setbacklight(high);   lcd.home();   lcd.print("voltage");   lcd.setcursor (0, 1);   lcd.print("pressure"); } void loop() { // averaging noise removal   float sensorvalue = analogread(a0);   float voltage = 5000.0 * sensorvalue * (1.0/1024.0);  // mv   float pressure = ((((voltage / 5) - 0.04) / 0.0012858)/1000.0) ;  // kpa   lcd.setcursor (10,0);   lcd.print(voltage);   delay(500);   lcd.setcursor (10,1);   lcd.print(pressure);   delay(500);   }

in attachments there data sheet sensor

after vcc connection on display i can see voltage  258.79 (in mv) and pressure 40.22 (and in kpa) this valuse softly lower or higher slight changes so me big offset of valid value

thank in advance help   

not idea see pressure sensor voltmeter.
your code assumes 5.000volt supply, nano on usb power more 4.6volt.
sensors ratiometric, , should convert directly a/d value pressure.

try example.
i calculated offset , span mpx5700, might need finetuning.

don't expect pressure sensor , 10-bit a/d (1024 values) can display 700 2 decimal places precision.
leo..

code: [select]

// mpx5700 pressure sensor (700kpa)

int rawvalue; // a/d readings
int offset = 41; // 0 pressure adjust
int fullscale = 963; // max pressure (span) adjust
float pressure; // final pressure

void setup() {
  serial.begin(9600);
}

void loop() {
  rawvalue = analogread(a0);
  pressure = (rawvalue - offset) * 700.0 / (fullscale - offset); // pressure conversion

  serial.print("raw a/d is  ");
  serial.print(rawvalue);
  serial.print("   pressure is  ");
  serial.print(pressure, 1); // 1 decimal places
  serial.println("  kpa");
  delay(500);
}
or, bit of averaging more stable readout , better offset adjustment.

code: [select]

// mpx5700 pressure sensor (700kpa)

int rawvalue; // a/d readings
int offset = 410; // 0 pressure adjust
int fullscale = 9630; // max pressure (span) adjust
float pressure; // final pressure

void setup() {
  serial.begin(9600);
}

void loop() {
  rawvalue = 0;
  (int x = 0; x < 10; x++) rawvalue = rawvalue + analogread(a0);
  pressure = (rawvalue - offset) * 700.0 / (fullscale - offset); // pressure conversion

  serial.print("raw a/d is  ");
  serial.print(rawvalue);
  serial.print("   pressure is  ");
  serial.print(pressure, 1); // 1 decimal places
  serial.println("  kpa");
  delay(500);
}
 

Arduino Forum > Using Arduino > Sensors > MPX5700GP pressure sensor

arduino