Arduino – smoothing out a bit

The relationship with the Arduino system is getting better. This is usually the case with new things – the more you know about them the more comfotable they get, the more you learn about them the better things seem to go.

It’s probably in the docs somewhere but I figured out that any library added in the libraries directory of the arduino software folder gets found automagicly. And any project in the examples directory can’t be overwritten. You make a directory called something like “Projects” within the arduino folder and the relationship improves.

After a few little “blinking light” type projects I wanted to get the LCD ColorShield from Sparkfun going. After weeding out the headaches of the colorlcdshield.h and colorLCDShield.cpp have to be within the libraries folder in the arduino folder, and then I had the PHILLIPS version not the EPSON version so you change lcd.init from EPSON to PHILLIPS, it worked. Then I started playing around a bit. Figured out the color definitions are a bit messed up, maybe because of the epson to phillips change. 0,0 is the top left corner which means the rows run down veritcally, etc. etc.

I took the TestPattern sketch (that’s what projects are called in Arduino) by Jim Lindblom and using it as a base made a scope program. I found it’s easier for me to do something useful while learning, I tend to learn better that way.

It works pretty good and is a good test bed for checking out the functions available.

The setup section: inits the 3 buttons that come with the LCD shield, sets up some constants, clears the screen to white, sets an array the size of the screen to 0 and draws a base line that separates the info section from the pattern section.

Things I wanted it to do – be able to still shot a pattern and give an average voltage.

The loop section: Do a loop that reads in the voltage at pin 0 and adds that number to the total. Then get the pixel position from the screen array and set that white. Now convert the input voltage to a screen X position and store it in the array place we just set white on the screen, then set the corresponding pixel on the screen blue.

After the loop runs 5 times I update the average voltage display. If I did it too soon it looked jumpy, this smooths things out a bit. There is also the if statement that checks button 0 and if pressed stops reading and just displays the existing pattern – that’s the hold system. Next maybe be able to adjust the delay with the buttons and then the voltage range. Also a way to calibrate it would be nice. But for now, here’s a pic and the sketch:
<a href=”http://leonzak.com/wp-content/uploads/2011/08/arduinopic12.jpg”><img src=”http://leonzak.com/wp-content/uploads/2011/08/arduinopic12-300×225.jpg” alt=”” title=”arduinopic1″ width=”300″ height=”225″ class=”alignnone size-medium wp-image-318″ /></a>
<pre>
/*
 TestPattern – An example sketch for the Color LCD Shield Library
 by: Jim Lindblom
 SparkFun Electronics
 date: 6/23/11
 license: CC-BY SA 3.0 – Creative commons share-alike 3.0
 use this code however you’d like, just keep this license and
 attribute. Let me know if you make hugely, awesome, great changes.

This sketch has example usage of the Color LCD Shield’s three
 buttons. It also shows how to use the setRect and contrast
 functions.

Hit S1 to increase the contrast, S2 decreases the contrast, and
 S3 sets the contrast back to the middle.
*/
#include <ColorLCDShield.h>
#include <stdlib.h>

LCDShield lcd;

int buttons[3] = {3, 4, 5}; // S1 = 3, S2 = 4, S3 = 5
byte cont = 40; // Good center value for contrast
// save these for later things int zero = 48; int A = 65; int a = 97;
char voltsIn[12];
int vin;
float temp;
float total = 0.0;
int screen[130];
int vinPoints = 1024; // v in can be 0 to 1023.
int screenLines = 130; // number of lines in the screen
int screenBottom = 98; // leave me 2 text lines for info and text
int useLines;
int scanCount = 0;
int scanDelay = 50; // picked this # outa my butt
int scanShow = 5; // same here

void setup()
{
for (int i=0; i<3; i++)
{
pinMode(buttons[i], INPUT); // Set buttons as inputs
digitalWrite(buttons[i], HIGH); // Activate internal pull-up
}
lcd.init(PHILLIPS); // Initialize the LCD, try using PHILLIPS if it’s not working
lcd.contrast(cont); // Initialize contrast
lcd.clear(WHITE); // Set background to white
for (int i=0; i<131; i++) {
screen[i] = 0; // clear the screen array so we know where we’re starting from
lcd.setPixel(BLACK, screenBottom+1, i); // as long as your going across, do the border line
}
useLines = screenLines – (screenLines – screenBottom); // get usable lines
lcd.setStr(”AV:”, screenLines – (1*16), 0, BLACK, WHITE); // static display part
}

void loop()
{
if (digitalRead(buttons[0])) // button 0 not pressed
{
for (int i=0; i<130; i++) {
vin = analogRead(0); // get a new reading
total = total + vin; // add it to the total so we can get an average later
lcd.setPixel(WHITE, screen[i], i); // clear the previous point
screen[i] = (-((float)vin / vinPoints) * useLines) + useLines;
lcd.setPixel(BLUE, screen[i], i);
}
scanCount = scanCount + 1;
if (scanCount > scanShow)
{
updateDisplay(); // only update the display once in while, less screen jitter, faster loop
}
}
delay(scanDelay);
}

void updateDisplay() {
temp = (float) ((total / (scanCount * 130)) / 1023) * 5; // get the avg volts read
dtostrf(temp, 5, 2, voltsIn); // make it a string
lcd.setStr(voltsIn, screenLines-16, 3*8, BLACK, WHITE); //display it
total = 0.0; // now start over
scanCount = 0;
}

</pre>

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Arduino – smoothing out a bit

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