#28824

I need a programming guru to look at my code and suggest the best way to convert tIhe?numeric data to ASCII. I am awaiting Dr Jack's book so I can learn the syntax. Right now I am in deepest Africa craving a beer and have no idea of the correct words to achieve my goal.

?/*

? A routine to convert from longitude and latitude to maidenhead grid squares

? Fred Hambrecht W4JLE

? */

?

void setup(){

Serial.begin(115200);

String grid (6);

String alpha = "ABCDEFGHIJLKMNOPQRSTUVWXYZ";

String num = "0123456789";

}

?

void loop()?

{

? int grid;

? int lon1, lon2, lon3;

? int lat1, lat2, lat3;

? double interim;

? double mylat;

? double mylon;

??

?

? //Example my location -81.401 33.904

? // longitude

? mylon = -81.401; ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? //static value for test

? interim = mylon + 180.0; ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?// -81.401 + 180 = 98.599

? lon1 = (int)(interim / 20.0); ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? // 98/20 = 4 Field Letter A+4 = E |depending on method 1 must be added to the value

? interim = interim - (double)lon1 * 20.0; ? ? ? ? ? ?// 98.599 - 4*20 = 18.599 ? ? ? ? |if I can fine a way to convert number to ASCII just add 65

? lon2 = (int)(interim *.5); ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?// 18/2 = 9 Square Number ? ? ? ? |48 or 97

? interim = interim - 2.0 * (double)lon2; ? ? ? ? ? ? ?// 18.599 - 2*9 = .599

? lon3 = (int)(12.0 * interim); ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? // .599 * 12 = 7 index to letter a+7 =h ?Sub Square letter

?

? // latitude

? mylat = 33.904; ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? //static value for test

? interim = mylat + 90.0; ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?// 33.904 + 90 = 123.903

? lat1 = (int)(interim / 10.0); ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? // 123/10 = 12 Field =M

? interim = interim - (double)mylat ?* 10.0; ? ? ? ? // 123.904 - 12*10 = 3.904

? lat2 = (int)(interim); ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? // 3 Square =3

? interim = interim - (double)lat2; ? ? ? ? ? ? ? ? ? ? ?// 3.123 - 3 =.904

? lat3 = (int)(24.0 * interim); ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?// .904 * 24 = 21.696 = 21 sub square = v

// Awaiting Dr Jack's book to get learn syntex for arrays and pointers ?

?//Help! I can add 65 to lon1 and lon3 or 48 to lon2 ?and convert to ASCII or add one and point to a letter in the alpha string

// or open to any suggestion. Thanks much, I am tearing what little hair I have left out!

?

}

?

#28826

Dr. Fred

This may help:

dtostrf is a function that converts a float or double into a character array using only one line of code

dtostrf(float, minimum width, precision, character array);

In Arduino IDE version of C+ they did not provide all the usual C-language capability to convert from float to

text or ASCII.? Thinking seems to be that the overhead was too large and slow if done in the Arduino library.

Instead they left it up to using "dtostrf" to do the heavy lifting.?

Arv? K7HKL
_._

Show quoted text

On Sun, Jun 25, 2017 at 2:49 PM, Dr Fred Hambrecht <AAR4MI@...> wrote:

I need a programming guru to look at my code and suggest the best way to convert tIhe?numeric data to ASCII. I am awaiting Dr Jack's book so I can learn the syntax. Right now I am in deepest Africa craving a beer and have no idea of the correct words to achieve my goal.

?/*

? A routine to convert from longitude and latitude to maidenhead grid squares

? Fred Hambrecht W4JLE

? */

?

void setup(){

Serial.begin(115200);

String grid (6);

String alpha = "ABCDEFGHIJLKMNOPQRSTUVWXYZ";

String num = "0123456789";

}

?

void loop()?

{

? int grid;

? int lon1, lon2, lon3;

? int lat1, lat2, lat3;

? double interim;

? double mylat;

? double mylon;

??

?

? //Example my location -81.401 33.904

? // longitude

? mylon = -81.401; ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? //static value for test

? interim = mylon + 180.0; ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?// -81.401 + 180 = 98.599

? lon1 = (int)(interim / 20.0); ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? // 98/20 = 4 Field Letter A+4 = E |depending on method 1 must be added to the value

? interim = interim - (double)lon1 * 20.0; ? ? ? ? ? ?// 98.599 - 4*20 = 18.599 ? ? ? ? |if I can fine a way to convert number to ASCII just add 65

? lon2 = (int)(interim *.5); ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?// 18/2 = 9 Square Number ? ? ? ? |48 or 97

? interim = interim - 2.0 * (double)lon2; ? ? ? ? ? ? ?// 18.599 - 2*9 = .599

? lon3 = (int)(12.0 * interim); ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? // .599 * 12 = 7 index to letter a+7 =h ?Sub Square letter

?

? // latitude

? mylat = 33.904; ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? //static value for test

? interim = mylat + 90.0; ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?// 33.904 + 90 = 123.903

? lat1 = (int)(interim / 10.0); ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? // 123/10 = 12 Field =M

? interim = interim - (double)mylat ?* 10.0; ? ? ? ? // 123.904 - 12*10 = 3.904

? lat2 = (int)(interim); ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? // 3 Square =3

? interim = interim - (double)lat2; ? ? ? ? ? ? ? ? ? ? ?// 3.123 - 3 =.904

? lat3 = (int)(24.0 * interim); ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?// .904 * 24 = 21.696 = 21 sub square = v

// Awaiting Dr Jack's book to get learn syntex for arrays and pointers ?

?//Help! I can add 65 to lon1 and lon3 or 48 to lon2 ?and convert to ASCII or add one and point to a letter in the alpha string

// or open to any suggestion. Thanks much, I am tearing what little hair I have left out!

?

}

?

#28833

Hi Dr. Fred.

Arv mentions one specific way to convert.

Another, more general way (at the expense of [I expect] more memory) is
to use snprintf(destinationBuffer, bufferSize, formatString, data...);
This is very similar to the normal "printf()" statement except it sends
the "output" to a character buffer rather than the standard output device.

"destinationBuffer" is a character string to hold the formatted data,
"bufferSize" is the size of the destination buffer (using sizeof() is very
useful for this variable), formatString is the normal "printf" style format
string, and "data..." is the data to format and place in the buffer.

This allows you to format integers, floating point, string, and just about
any thing else.  Very useful, unless you get really memory constrained.
(Then there are other techniques which may be used.)

BTW, you will also see "sprintf()" used, but it has the "problem" that is
is all too easy to overwrite the destination buffer resulting in general
corruption.  Something which may be extremely difficult to diagnose.

I hope this helps.

73

- Mark  N1VQW

#28840

Mark and Dr. Fred

Unless it has been fixed in the past few months, the built-in Arduino.h does not

implement sprintf(%f).? It does not block...it just does nothing.? This is a long-

standing bug in the Arduino IDE that the IDE developers do not see as a problem.

Example of the problem:

char temperature[10];
float temp = 10.55;
sprintf(temperature,"%f F", temp);
Serial.println(temperature);

Arv? K7HKL
_._

Show quoted text

On Sun, Jun 25, 2017 at 5:41 PM, Mark Pilant <mark@...> wrote:

Hi Dr. Fred.

Arv mentions one specific way to convert.

Another, more general way (at the expense of [I expect] more memory) is
to use snprintf(destinationBuffer, bufferSize, formatString, data...);
This is very similar to the normal "printf()" statement except it sends
the "output" to a character buffer rather than the standard output device.

"destinationBuffer" is a character string to hold the formatted data,
"bufferSize" is the size of the destination buffer (using sizeof() is very
useful for this variable), formatString is the normal "printf" style format
string, and "data..." is the data to format and place in the buffer.

This allows you to format integers, floating point, string, and just about
any thing else.? Very useful, unless you get really memory constrained.
(Then there are other techniques which may be used.)

BTW, you will also see "sprintf()" used, but it has the "problem" that is
is all too easy to overwrite the destination buffer resulting in general
corruption.? Something which may be extremely difficult to diagnose.

I hope this helps.

73

- Mark? N1VQW

Jack Purdum

#28841

No, it's not a problem for several reasons. First, sprintf() is a very powerful function yet most programs use only a fraction of its power. Result: a lot of wasted memory. Instead, try:

char temperature[10]; float temp = 10.55; //sprintf(temperature,"%f F", temp);

dtostrf(temp, 7, 2, temperature); Serial.println(temperature);

The 7 is the digit width of the field for the number while the 2 is the number of digits after the decimal point. The function also uses less memory than sprintf(). Keep in mind that the Arduino IDE does not support the double data type and that the best you can hope for with a float is about 7 digits of precision. Any digits after that it a guess.

Jack, W8TEE

Show quoted text

From: Arv Evans <arvid.evans@...>
To: [email protected]
Sent: Sunday, June 25, 2017 9:28 PM
Subject: Re: [BITX20] Help!

Mark and Dr. Fred

Unless it has been fixed in the past few months, the built-in Arduino.h does not

implement sprintf(%f).? It does not block...it just does nothing.? This is a long-

standing bug in the Arduino IDE that the IDE developers do not see as a problem.

Example of the problem:

char temperature[10];
float temp = 10.55;
sprintf(temperature,"%f F", temp);
Serial.println(temperature);

Arv? K7HKL
_._

On Sun, Jun 25, 2017 at 5:41 PM, Mark Pilant <mark@...> wrote:

Hi Dr. Fred.

Arv mentions one specific way to convert.

Another, more general way (at the expense of [I expect] more memory) is
to use snprintf(destinationBuffer, bufferSize, formatString, data...);
This is very similar to the normal "printf()" statement except it sends
the "output" to a character buffer rather than the standard output device.

"destinationBuffer" is a character string to hold the formatted data,
"bufferSize" is the size of the destination buffer (using sizeof() is very
useful for this variable), formatString is the normal "printf" style format
string, and "data..." is the data to format and place in the buffer.

This allows you to format integers, floating point, string, and just about
any thing else.? Very useful, unless you get really memory constrained.
(Then there are other techniques which may be used.)

BTW, you will also see "sprintf()" used, but it has the "problem" that is
is all too easy to overwrite the destination buffer resulting in general
corruption.? Something which may be extremely difficult to diagnose.

I hope this helps.

73

- Mark? N1VQW

Virus-free.

Vince Vielhaber

#28843

A year or so ago someone on the arduino forum told me that sprintf is there but turned off to conserve memory.  They told me what to do to get it to work but I never could get it to.

There's a package for formatting string buffers called PString, but I don't see it being as much use as a simple sprintf or snprintf.

Vince.

Show quoted text

On 06/25/2017 09:27 PM, Arv Evans wrote:
Mark and Dr. Fred

Unless it has been fixed in the past few months, the built-in Arduino.h
does not
implement sprintf(%f).  It does not block...it just does nothing.  This
is a long-
standing bug in the Arduino IDE that the IDE developers do not see as a
problem.

Example of the problem:

|chartemperature[10];floattemp =10.55;sprintf(temperature,"%f
F",temp);Serial.println(temperature);|




Arv  K7HKL
_._

-- 
  Michigan VHF Corp.      
                          

Jack Purdum

#28844

Fred:

Try this: it avoids using the String class, which is a memory hog.

void setup() {

? // put your setup code here, to run once:

? char answer[15];

? Serial.begin(115200);

? calcLocator(answer, 39.035344, -84.261335); // Enter lat, then lon

? Serial.println(answer);

}

void calcLocator(char *dst, float lat, float lon) {

? int o1, o2, o3;

? int a1, a2, a3;

? float remainder;

? // longitude

? remainder = lon + 180.0;

? o1 = (int)(remainder / 20.0);

? remainder = remainder - (float)o1 * 20.0;

? o2 = (int)(remainder / 2.0);

? remainder = remainder - 2.0 * (float)o2;

? o3 = (int)(12.0 * remainder);

? // latitude

? remainder = lat + 90.0;

? a1 = (int)(remainder / 10.0);

? remainder = remainder - (float)a1 * 10.0;

? a2 = (int)(remainder);

? remainder = remainder - (float)a2;

? a3 = (int)(24.0 * remainder);

? dst[0] = (char)o1 + 'A';

? dst[1] = (char)a1 + 'A';

? dst[2] = (char)o2 + '0';

? dst[3] = (char)a2 + '0';

? dst[4] = (char)o3 + 'A';

? dst[5] = (char)a3 + 'A';

? dst[6] = (char)0;

}

void loop() {

}

Jack, W8TEE

Show quoted text

From: Dr Fred Hambrecht <AAR4MI@...>
To: [email protected]
Sent: Sunday, June 25, 2017 4:49 PM
Subject: [BITX20] Help!