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High Precision Barometric Pressure sensor using the Wio terminal

Overview

The demo shows that the Grove- high precision pressure sensor DPS310 is fully compatible with the Wio terminal, and its measurement has high precision.

Features

  • The range of normal atmospheric pressure values can be display by the dial colour
  • with the time to display the temperature degrees
  • High precision barometric pressure and temperature detection

Hardware

Hardware Connection

software

if you do not have The Arduino IDE, please view The Get Started with Wio Terminal

Code

#include <Dps310.h>
#include <SPI.h>
#include <TFT_eSPI.h> // Hardware-specific library
TFT_eSPI tft = TFT_eSPI();

#define TFT_GREY 0x5AEB
#define LOOP_PERIOD 35 // Display updates every 35 ms

Dps310 Dps310PressureSensor = Dps310();

#define M_SIZE 1.4

TFT_eSprite spr = TFT_eSprite(&tft); // Sprite

float ltx = 0; // Saved x coord of bottom of needle
uint16_t osx = M_SIZE * 120, osy = M_SIZE * 120; // Saved x & y coords
uint32_t updateTime = 0; // time for next update

int old_analog = -999; // Value last displayed

int value[6] = {0, 0, 0, 0, 0, 0};
int d = 0;

void setup(void) {
tft.begin();
tft.init();
tft.setRotation(3);
Serial.begin(57600); // For debug
tft.fillScreen(TFT_WHITE);
spr.createSprite(TFT_HEIGHT,TFT_WIDTH);
spr.setRotation(3);

Dps310PressureSensor.begin(Wire);
analogMeter(); // Draw analogue meter

updateTime = millis(); // Next update time
}


void loop() {
float temperature;
float pressure;
uint8_t oversampling = 7;
int16_t ret;

ret = Dps310PressureSensor.measureTempOnce(temperature, oversampling);
ret = Dps310PressureSensor.measurePressureOnce(pressure, oversampling);
Serial.println(pressure);

if (updateTime <= millis()) {
updateTime = millis() + 35; // Update emter every 35 milliseconds

// Create a Sine wave for testing
d += 4;
if (d >= 360) {
d = 0;
}
////////////////////////////////////////////////////////
// this is a excmple, you just need to del '- 100050'
////////////////////////////////////////////////////////
plotNeedle(pressure-100050, 0); // It takes between 2 and 12ms to replot the needle with zero delay
}

delay(100);
spr.fillSprite(TFT_WHITE);
spr.createSprite(250, 40);
spr.fillSprite(TFT_WHITE);
spr.setTextColor(TFT_BLACK, TFT_WHITE);
spr.setFreeFont(&FreeSansBoldOblique12pt7b);
spr.drawNumber(temperature, 0, 0);
spr.drawString(" °C", 30, 0);
spr.drawNumber(pressure, 120,0);
spr.drawString("Pa", 210,0);
spr.pushSprite(30, 190);
spr.deleteSprite();

}


// #########################################################################
// Draw the analogue meter on the screen
// #########################################################################
void analogMeter() {

// Meter outline
tft.fillRect(0, 0, M_SIZE * 239, M_SIZE * 126, TFT_GREY);
tft.fillRect(5, 3, M_SIZE * 230, M_SIZE * 119, TFT_WHITE);

tft.setTextColor(TFT_BLACK); // Text colour

// Draw ticks every 5 degrees from -50 to +50 degrees (100 deg. FSD swing)
for (int i = -50; i < 51; i += 5) {
// Long scale tick length
int tl = 15;

// Coodinates of tick to draw
float sx = cos((i - 90) * 0.0174532925);
float sy = sin((i - 90) * 0.0174532925);
uint16_t x0 = sx * (M_SIZE * 100 + tl) + M_SIZE * 120;
uint16_t y0 = sy * (M_SIZE * 100 + tl) + M_SIZE * 140;
uint16_t x1 = sx * M_SIZE * 100 + M_SIZE * 120;
uint16_t y1 = sy * M_SIZE * 100 + M_SIZE * 140;

// Coordinates of next tick for zone fill
float sx2 = cos((i + 5 - 90) * 0.0174532925);
float sy2 = sin((i + 5 - 90) * 0.0174532925);
int x2 = sx2 * (M_SIZE * 100 + tl) + M_SIZE * 120;
int y2 = sy2 * (M_SIZE * 100 + tl) + M_SIZE * 140;
int x3 = sx2 * M_SIZE * 100 + M_SIZE * 120;
int y3 = sy2 * M_SIZE * 100 + M_SIZE * 140;

// Yellow zone limits
if (i >= -50 && i < -25) {
tft.fillTriangle(x0, y0, x1, y1, x2, y2, TFT_GREEN);
tft.fillTriangle(x1, y1, x2, y2, x3, y3, TFT_GREEN);
}

if (i >= -25 && i < 0) {
tft.fillTriangle(x0, y0, x1, y1, x2, y2, TFT_YELLOW);
tft.fillTriangle(x1, y1, x2, y2, x3, y3, TFT_YELLOW);
}

// Green zone limits
if (i >= 0 && i < 25) {
tft.fillTriangle(x0, y0, x1, y1, x2, y2, TFT_RED);
tft.fillTriangle(x1, y1, x2, y2, x3, y3, TFT_RED);
}

// Orange zone limits
if (i >= 25 && i < 50) {
tft.fillTriangle(x0, y0, x1, y1, x2, y2, TFT_RED);
tft.fillTriangle(x1, y1, x2, y2, x3, y3, TFT_RED);
}

// Short scale tick length
if (i % 25 != 0) {
tl = 8;
}

// Recalculate coords incase tick lenght changed
x0 = sx * (M_SIZE * 100 + tl) + M_SIZE * 120;
y0 = sy * (M_SIZE * 100 + tl) + M_SIZE * 140;
x1 = sx * M_SIZE * 100 + M_SIZE * 120;
y1 = sy * M_SIZE * 100 + M_SIZE * 140;

// Draw tick
tft.drawLine(x0, y0, x1, y1, TFT_BLACK);

// Check if labels should be drawn, with position tweaks
if (i % 25 == 0) {
// Calculate label positions
x0 = sx * (M_SIZE * 100 + tl + 10) + M_SIZE * 120;
y0 = sy * (M_SIZE * 100 + tl + 10) + M_SIZE * 140;

////////////////////////////////////////////////////////////
// In here, you can change the dial plate
////////////////////////////////////////////////////////////
switch (i / 25) {
case -2: tft.drawCentreString("100000", x0, y0 - 12, 2); break;
case -1: tft.drawCentreString("100025", x0, y0 - 9, 2); break;
case 0: tft.drawCentreString("100050", x0, y0 - 7, 2); break;
case 1: tft.drawCentreString("100075", x0, y0 - 9, 2); break;
case 2: tft.drawCentreString("100100", x0, y0 - 12, 2); break;
}
}

// Now draw the arc of the scale
sx = cos((i + 5 - 90) * 0.0174532925);
sy = sin((i + 5 - 90) * 0.0174532925);
x0 = sx * M_SIZE * 100 + M_SIZE * 120;
y0 = sy * M_SIZE * 100 + M_SIZE * 140;
// Draw scale arc, don't draw the last part
if (i < 50) {
tft.drawLine(x0, y0, x1, y1, TFT_BLACK);
}
}

//tft.drawString("%RH", M_SIZE * (5 + 230 - 40), M_SIZE * (119 - 20), 2); // Units at bottom right
tft.drawCentreString("K/Pa", M_SIZE * 120, M_SIZE * 80, 4); // Comment out to avoid font 4
tft.drawRect(5, 3, M_SIZE * 230, M_SIZE * 119, TFT_BLACK); // Draw bezel line

plotNeedle(0, 0); // Put meter needle at 0
}

// #########################################################################
// Update needle position
// This function is blocking while needle moves, time depends on ms_delay
// 10ms minimises needle flicker if text is drawn within needle sweep area
// Smaller values OK if text not in sweep area, zero for instant movement but
// does not look realistic... (note: 100 increments for full scale deflection)
// #########################################################################
void plotNeedle(int value, byte ms_delay) {

if (value < -10) {
value = -10; // Limit value to emulate needle end stops
}
if (value > 110) {
value = 110;
}

// Move the needle until new value reached
while (!(value == old_analog)) {
if (old_analog < value) {
old_analog++;
} else {
old_analog--;
}

if (ms_delay == 0) {
old_analog = value; // Update immediately if delay is 0
}

float sdeg = map(old_analog, -10, 110, -150, -30); // Map value to angle
// Calcualte tip of needle coords
float sx = cos(sdeg * 0.0174532925);
float sy = sin(sdeg * 0.0174532925);

// Calculate x delta of needle start (does not start at pivot point)
float tx = tan((sdeg + 90) * 0.0174532925);

// Erase old needle image
tft.drawLine(M_SIZE * (120 + 20 * ltx - 1), M_SIZE * (140 - 20), osx - 1, osy, TFT_WHITE);
tft.drawLine(M_SIZE * (120 + 20 * ltx), M_SIZE * (140 - 20), osx, osy, TFT_WHITE);
tft.drawLine(M_SIZE * (120 + 20 * ltx + 1), M_SIZE * (140 - 20), osx + 1, osy, TFT_WHITE);

// Re-plot text under needle
tft.setTextColor(TFT_BLACK);
tft.drawCentreString("K/Pa", M_SIZE * 120, M_SIZE * 80, 4); // // Comment out to avoid font 4

// Store new needle end coords for next erase
ltx = tx;
osx = M_SIZE * (sx * 98 + 120);
osy = M_SIZE * (sy * 98 + 140);

// Draw the needle in the new postion, magenta makes needle a bit bolder
// draws 3 lines to thicken needle
tft.drawLine(M_SIZE * (120 + 20 * ltx - 1), M_SIZE * (140 - 20), osx - 1, osy, TFT_RED);
tft.drawLine(M_SIZE * (120 + 20 * ltx), M_SIZE * (140 - 20), osx, osy, TFT_MAGENTA);
tft.drawLine(M_SIZE * (120 + 20 * ltx + 1), M_SIZE * (140 - 20), osx + 1, osy, TFT_RED);

// Slow needle down slightly as it approaches new postion
if (abs(old_analog - value) < 10) {
ms_delay += ms_delay / 5;
}

// Wait before next update
delay(ms_delay);
}
}

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