Transmit X axis accelerometer data to PC for graphing

Dependencies:   MMA8451Q mbed



File content as of revision 0:c9bb3c9d5ce8:

#include "mbed.h"
#include "MMA8451Q.h"

// define I2C Pins and address for KL25Z. Taken from default sample code.
PinName const SDA = PTE25;
PinName const SCL = PTE24;
#define MMA8451_I2C_ADDRESS (0x1d<<1)

//serial connection to PC via USB
Serial pc(USBTX, USBRX);

int main(void)
    //configure on-board I2C accelerometer on KL25Z
    MMA8451Q acc(SDA, SCL, MMA8451_I2C_ADDRESS);
    float x;
    while (true) {
        x = acc.getAccX(); //get acceleration
        pc.printf("%1.2f\n", x); //print ascii-encoded float to serial port
        wait(0.05f); // wait 50ms (20Hz update rate)

// Graphing sketch for Processing

// This program takes ASCII-encoded strings containing floating point numbers
// from the serial port at 9600 baud and graphs them. It expects values in the
// range -1.0 to 1.0, followed by a newline, or newline and carriage return

// Created 20 Apr 2005
// Updated 18 Jan 2008 by Tom Igoe
// Adapted 16 Sep 2014 by Bjoern Hartmann for mbed
// This example code is in the public domain.

import processing.serial.*;

Serial myPort;        // The serial port
int xPos = 1;         // horizontal position of the graph

float minVal=-1.0;
float maxVal=1.0;

void setup () {
  // set the window size:
  size(400, 300);        

  // List all the available serial ports
  // Open whatever port is the one you're using.
  myPort = new Serial(this, "/dev/tty.usbmodem1412", 9600);
  // don't generate a serialEvent() unless you get a newline character:
  // set inital background:
void draw () {
  // everything happens in the serialEvent()

void serialEvent (Serial myPort) {
  // get the ASCII string:
  String inString = myPort.readStringUntil('\n');

  if (inString != null) {
    // trim off any whitespace:
    inString = trim(inString);
    // convert to an int and map to the screen height:
    float inFloat = float(inString); 
    float screenY = map(inFloat, minVal, maxVal, 0, height);

    // draw the line from bottom of screen to desired height
    stroke(127, 34, 255);
    line(xPos, height, xPos, height - screenY);

    // at the edge of the screen, go back to the beginning:
    if (xPos >= width) {
      xPos = 0;
    } else {
      // increment the horizontal position: