PCom Update: multiple serial input

L.J — Wed, 15 Oct 2008 06:11:52 +0000

I’ve been mostly working on viz class and pcom mid term over the weekend. One big thing is I once made the eight-buck-deal RF Link work in the studio, but never succeeded in testing again since I went back to the dorm. I used software serial library to utilize digital pins as serial input/output and leave the original serial port for computer monitoring, but the RL Links still feel like a black box to me. The transmitter side looks working perfectly while I hooked up a USB cable and tried to read the TX stream, however the receiver side keeps getting rubbish data. More efforts are to be invested on this issue!!

Just a quick update on the multi-serial-input, shown as the video below (yes I still love my force sensors):

It’s pretty simple, just using two serial inputs. But the concept of encoding data and protocol is pretty clear.

Arduino Code:

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int leftPin = 4;
int rightPin = 5;
int leftValue,rightValue;

void setup()
{
beginSerial(9600); //set up communication back to pc
}

void loop()
{
leftValue = analogRead(leftPin);
rightValue = analogRead(rightPin);

//if (abs(leftValue - rightValue) > 50)
//{
Serial.print(leftValue,DEC);
Serial.print(44,BYTE);
Serial.print(rightValue,DEC);
Serial.print(44,BYTE);
Serial.println();
//}
}

Processing Code:

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import processing.serial.*;

Serial myPort;
String data;
int leftValue = 0;
int rightValue = 0;

void setup()
{
size(800, 600, P3D);
directionalLight(126, 126, 126, 0, 0, -1);
ambientLight(102, 102, 102);
noStroke();
myPort = new Serial(this, Serial.list()[0], 9600);
ellipseMode(CENTER);
}

void draw()
{
background(0);
float leftR = map(leftValue,0,1023,0,PI/2);
float rightR = map(rightValue,0,1023,0,PI/2);

translate(width/2, height/2);

rotateX(-PI/12);
rotateZ(rightR - leftR);
stroke(160,10);
fill(150,150,150,90);
box(500,10,100);
translate(0,10);

noStroke();
fill(255,0,0);
translate(map(rightValue - leftValue,-1023,1023,-250,250),-25);
sphere(10);
}

void serialEvent(Serial p) {
String input = p.readStringUntil(10); //make sure you return (Ascii 13) at the end of your transmission
if (input != null)
{
String[] parts = input.split(","); //this will only work if you put commas (Ascii 44) between things in your transmission

if (parts.length >= 2)
{
//println("Raw Input: " + input);
if (abs(int(parts[0]) - leftValue) > 10)
{
leftValue = int(parts[0]);
}
if (abs(int(parts[1]) - rightValue) > 10)
{
rightValue = int(parts[1]);
}
}
}
}

PCom: Serial Input in Processing

L.J — Wed, 08 Oct 2008 15:42:33 +0000

I do enjoy the force sensor I got in week 5′s application class so I’ll definitely use it more in the assignment!

First I revisited the processing codes I wrote for week 2, which now seems to be a total mess. I didn’t know about the serialEvent callback then so I parsed the serial input in the draw loop, and I didn’t use BYTE output in the arduino board so I need to parse it as string. It worked pretty well but the revised the version is much better.

Codes:

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import processing.serial.*;

Serial myPort;
int window = 800;
int[] values = new int[window - 100];
int index = 0;
int input = 0;

void setup()
{
size(window,window);
background(0,30);
smooth();
// List all the available serial ports:
//println(Serial.list());
myPort = new Serial(this, Serial.list()[0], 9600);

for (int i = 0;i<window - 100;i++)
{
values[i] = 0;
}
}

void draw()
{
background(0,20);
for (int i = 0; i < window - 100;i++)
{
int j = i + index;
if (j >= (window - 100))
{
j = j - (window - 100);
}

stroke(255,0,0,80);
line(50 + i, (window - 50), 50 + i, (window - 50) - (values[j] * (window - 100) / 1024));
stroke(255,0,0,100);
point(50 + i, (window - 50));
point(50 + i, (window - 50) - (values[j] * (window - 100) / 1024));
}
}

void serialEvent(Serial p) {
input = p.read();
println("input:" + input);
values[index] = input * 4;
index++;
if (index >= window - 100)
{
index = index - (window - 100);
}
}

Then I thought about the nature of the force sensor and really wished I could visualize the “force” in the processing. So I adopted the “string” example bundled in the processing application and integrated it with the serial input.

Codes:

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import processing.serial.*;
// The serial port:
Serial myPort;
int input = 0;
int lastInput = -1;

// Spring drawing constants for top bar
int s_height = 16; // Height
int left = 150; // Left position
int right = 250; // Right position
int max = 300; // Maximum Y value
int min = 20; // Minimum Y value
boolean over = true; // If mouse over
boolean move = false; // If mouse down and over

// Spring simulation constants
float M = 0.8; // Mass
float K = 0.2; // Spring constant
float D = 0.92; // Damping
float R = 60; // Rest position

// Spring simulation variables
float ps = 60.0; // Position
float vs = 0.0; // Velocity
float as = 0; // Acceleration
float f = 0; // Force

void setup()
{
size(400, 400);
rectMode(CORNERS);
noStroke();
myPort = new Serial(this, Serial.list()[0], 9600);
}

void draw()
{
background(102);
updateSpring();
drawSpring();
}

void drawSpring()
{
// Draw base
fill(0.2);
float b_width = 0.5 * ps + -8;
rect(width/2 - b_width, ps + s_height, width/2 + b_width, 350);
}

void updateSpring()
{
// Update the spring position
if(!move) {
f = -K * (ps - R); // f=-ky
as = f / M; // Set the acceleration, f=ma == a=f/m
vs = D * (vs + as); // Set the velocity
ps = ps + vs; // Updated position
}
if(abs(vs) < 0.1) {
vs = 0.0;
}

// Test if mouse is over the top bar
/*
if(mouseX > left && mouseX < right && mouseY > ps && mouseY < ps + s_height) {
over = true;
} else {
over = false;
}
*/

// Set and constrain the position of top bar
if(move) {
ps = map(input,0,255,min,max) - s_height/2;
if (ps < min) { ps = min; }
if (ps > max) { ps = max; }
}
}

void serialEvent(Serial p) {
input = p.read();
println("input:" + input);

if (input > lastInput)
{
move = true;
}
else if (lastInput > input + 10 || input < 10)
{
move = false;
}

lastInput = input;
}

lithium flowers bloom » force sensor

PCom Update: multiple serial input

PCom: Serial Input in Processing