Jayduino

Arduino stuff written by me and released into the public domain.

BMA180 acceleration sensor
DS1307 Real time clock
DCF77 reads atomic clock transmission
fasterAnalogRead
VFDM12 cool and cheap VFD-display (alpha)
ysecTimer2 handy microsecond timer
Filter Suite
TDOA calculation for 4 rectangle positioned sensors

To Be Published:

LCD64240B a huge matrix display (240x64)

VFD128x64 another nice VFD matrix display (128x64 pixels)

BMA180

Library (not complete) for BOSCH BMA180 acceleration sensor. Note that you need to convert the levels of the sensor to 3.3V. Comunication via I2C interface. There is also an example to use the Interrupt pin of the BMA180.
Download the library bma180.zip or browse the files.

DS1307 RTC

Library for the Real Time Clock DS1307. Contains also interrupt driven example for the SQW pin.
Download the library: DS1307.zip or browse the files. Some tips: if the DS1306 SQW/OUT deos not work even if you have set the register and you are sure that your ISR is working you need to:

switch off everything
unplug the backup battery
switch on
plug the battery (on or off, doesn't matter)
Reset the time and activate the ctrl_register

This should bring it back to life. If you don't want a battery backup: connect the Battery VDD to GND. I personally use the DS1307 mostly for realtime logging and clocks and the ISR for accurate pitch detection (the arduino is sometimes badly off). For the pitch detection i use the 32Khz interrupt and a counter. for every second should be exactely 32768 ticks (depends how much the 32Khz OSC is off).
See also the DCF77 library to read an atomic clock transmission (central europe only)

DCF77 library

DCF77 is an RF sender that transmits timecodes in central europe, using a simple receiver you can retrieve the exact time.
My DCF77 library contains various useful things like:

signal quality indication
minimum use of sampling (using external interrupt pin 2 or 3)
minute and seconds callback functions
plausibility check on data
drift calculation of internal clock (msecs/min)

Included are various examples showing it's use in combination with:

serial mode
a real time clock (you need the DS1307 library)
vfd-displays + RTC
servos (dynamixel AX-12) as a watch

but be warned, it is far from complete and clean.
Download the library DCF77ISR.zip or browse the files.

fasterAnalogRead

A way to read the analog input with less waitstates (make a sampling request, do what you like to do, read the value). Also to make the acquisition faster (but less precise resolution).
Download the library: fasterAnalogRead.zip or browse the files.

VFDM12

A library for the nice (and cheap) 12 digits flourescent display Futaba VFD M12BY022AA. Comunication via I2C (so you leave your Serial port free and it is damn fast).
Download the library: VFDM12.zip or browse the files.

ysecTimer2

Library that 'hijacks' the Timer2 with ysecs resolution. Ideal for some kinds of data acquisition (> 1khz).
Download the library: ysecTimer2.zip or browse the files.

Filter Suite

A form to create realtime filters (i.e. audio or for nervous sensors). Optimized for Arduino short to long (16bit signed) operations. Filters included are

IIR Lowpass, Highpass, Bandpass, Bandstop using Bessel, Chebychef and Butterworth from 1st to 5th order (3rd to 5th order are critical in short, use the floating point if you really need them).
IIR Resonanz Filter make it ring...
Proportional Integral Filter industrial control stuff
(not yet added) FIR MovingAverage and Binomial filters for various length

All filters use constant coefficients to obtain faster calculation (so no dynamic filters included). you have only to calculate the factor of your filter (hz/samplerate) and include the filter you need. I am counting on adding convolution and pitchdetection algorithms and to provide a web interface so you can design your own DIY ready-to-use filter code.

Newton method for sound distance analysis (TDOA)

Not actually so much Arduino, but I needed this to solve a problem for an automatic remote 3D-helicopter camera: find the EXACT position of an heli using four mics placed at corners of a rectangle. The heli emits an ultrasonic sound pattern (kind of inversed bat). I think it could have applications in many situations. Measuring positions of any noise creating object. Helping blind people orientation. Active precise measurement of positions in athletics (with an ultrasonic emitter).
New: Gave a try to matlab to solve the equation and it got a result, BUT when testing them they did not get the right results!

>> solve('r+t-sqrt((a-((q+t)^2-t^2-a^2)/(-2*a))^2+(b-((p+t)^2-t^2-b^2)/(-2*b))^2)')	
 t=-(a^2*p^3 + b^2*q^3 + a^2*b^2*p + a^2*b^2*q - 2*a^2*b^2*r + a*b*(a^4*b^2 - a^4*p^2 + a^2*b^4 + 2*a^2*b^2*p^2 + 2*a^2*b^2*p*q - 4*a^2*b^2*p*r + 2*a^2*b^2*q^2 - 4*a^2*b^2*q*r + a^2*p^4 + 2*a^2*p^3*q - 4*a^2*p^3*r - 2*a^2*p^2*q^2 + 4*a^2*p^2*r^2 - b^4*q^2 - 2*b^2*p^2*q^2 + 2*b^2*p*q^3 + b^2*q^4 - 4*b^2*q^3*r + 4*b^2*q^2*r^2 - p^4*q^2 + 2*p^3*q^3 - p^2*q^4)^(1/2))/(- 2*a^2*b^2 + 2*a^2*p^2 + 2*b^2*q^2)
 t=-(a^2*p^3 + b^2*q^3 + a^2*b^2*p + a^2*b^2*q - 2*a^2*b^2*r - a*b*(a^4*b^2 - a^4*p^2 + a^2*b^4 + 2*a^2*b^2*p^2 + 2*a^2*b^2*p*q - 4*a^2*b^2*p*r + 2*a^2*b^2*q^2 - 4*a^2*b^2*q*r + a^2*p^4 + 2*a^2*p^3*q - 4*a^2*p^3*r - 2*a^2*p^2*q^2 + 4*a^2*p^2*r^2 - b^4*q^2 - 2*b^2*p^2*q^2 + 2*b^2*p*q^3 + b^2*q^4 - 4*b^2*q^3*r + 4*b^2*q^2*r^2 - p^4*q^2 + 2*p^3*q^3 - p^2*q^4)^(1/2))/(- 2*a^2*b^2 + 2*a^2*p^2 + 2*b^2*q^2)

the working program


double a=210; // distance in m	
double b=140; // distance in m	
	
#define SQR(x) ((x)*(x))
#define TRI(x) ((x)*(x)*(x))
#define QUAD(x) ((x)*(x)*(x)*(x))


/* and this are the functions f(x) and f'(x) for the newton method
 * approximation step is xn1=xn-f(xn, p, q, r)/f1(xn, p, q, r);
* 

* 

*/

double f(double t, double p, double q, double r)
{
	return r+t-sqrt(SQR(a-(SQR(q+t)-SQR(t)-SQR(a))/(-2*a))+SQR(b-(SQR(p+t)-SQR(t)-SQR(b))/(-2*b)));
}

/* ok, this one is terrible... ;)
*/
double f1(double x, double p, double q, double r)
{
	return (SQR(a)*SQR(b)*sqrt((4*SQR(b)*SQR(q)+4*SQR(a)*SQR(p))*SQR(x)+
		(4*SQR(b)*TRI(q)+4*SQR(a)*SQR(b)*q+4*SQR(a)*TRI(p)+
		4*SQR(a)*SQR(b)*p)*x+SQR(b)*QUAD(q)+2*SQR(a)*SQR(b)*SQR(q)+
		SQR(a)*QUAD(p)+2*SQR(a)*SQR(b)*SQR(p)+SQR(a)*QUAD(b)+QUAD(a)*SQR(b))+
		(-2*fabs(a)*SQR(b)*fabs(b)*SQR(q)-2*SQR(a)*fabs(a)*fabs(b)*SQR(p))*x-
		fabs(a)*SQR(b)*fabs(b)*TRI(q)-SQR(a)*fabs(a)*SQR(b)*fabs(b)*q-
		SQR(a)*fabs(a)*fabs(b)*TRI(p)-SQR(a)*fabs(a)*SQR(b)*fabs(b)*p)/
		(SQR(a)*SQR(b)*sqrt((4*SQR(b)*SQR(q)+4*SQR(a)*SQR(p))*SQR(x)+
		(4*SQR(b)*TRI(q)+4*SQR(a)*SQR(b)*q+4*SQR(a)*TRI(p)+4*SQR(a)*SQR(b)*p)*x+
		SQR(b)*QUAD(q)+2*SQR(a)*SQR(b)*SQR(q)+SQR(a)*QUAD(p)+
		2*SQR(a)*SQR(b)*SQR(p)+SQR(a)*QUAD(b)+QUAD(a)*SQR(b)));
}


void getxy(double t, double p, double q, double a, double b, double *x, double *y)
{
	*x=(SQR(q)-SQR(t)-SQR(a))/(-2*a);
	*y=(SQR(p)-SQR(t)-SQR(b))/(-2*b);
}


/* pass the measured times of a qudrant delta t's, t3 being the opposite corner of the qudrant.
*/
void newtonFindXY(double t1, double t2, double t3, double eps, double *xres, double *yres)
{
	double xn1;
	double xn=(a+b)/2-t3;
	
	printf("x=%.1f ",xn);
	for (int i=1; i <= 10; i++)
	{
		xn1=xn-f(xn, t1, t2, t3)/f1(xn, t1, t2, t3);
		printf("%.1f ",xn1);
		if (fabs(xn-xn1) < eps)
		{
			break;
		}
		xn=xn1;
	}
	getxy(xn1, t1+xn1, t2+xn1, a, b, xres, yres);
}

Enjoy or send an email to Jürgen Schwietering