I have an arudino code where I get some temperature reading:
double c1 = device.readCelsius();
Serial.println(c1);
The output is for example: 26.23
What I need is to get this converted to 2623 and then to HEX value so I get: 0x0A3F
Any clue?
I guess your float values always get numbers up to two decimal. So, you can just multiply the value which you read from sensor with a 100.
decimalValue = 100 * c1
And then you can use this small code for converting the decimal value to HEX.
Thanks to GeeksforGeeks
You can find the full tutorial here
// C++ program to convert a decimal
// number to hexadecimal number
#include <iostream>
using namespace std;
// function to convert decimal to hexadecimal
void decToHexa(int n)
{
// char array to store hexadecimal number
char hexaDeciNum[100];
// counter for hexadecimal number array
int i = 0;
while (n != 0) {
// temporary variable to store remainder
int temp = 0;
// storing remainder in temp variable.
temp = n % 16;
// check if temp < 10
if (temp < 10) {
hexaDeciNum[i] = temp + 48;
i++;
}
else {
hexaDeciNum[i] = temp + 55;
i++;
}
n = n / 16;
}
// printing hexadecimal number array in reverse order
for (int j = i - 1; j >= 0; j--)
cout << hexaDeciNum[j];
}
// Driver program to test above function
int main()
{
int n = 2545;
decToHexa(n);
return 0;
}
Related
I'm trying to convert a string to an integer (which is actually a binary number) so that I can output the DEC value, but where the answer SHOULD be 63 (00111111), it's giving me -19961 as an output? It would be great if someone can help me correctly convert the string to an int :)
// C++ code
//
const int button = 13;
int buttonPressed = 0;
int counter = 0;
int myInts[] = {0, 0, 1, 1, 1, 1, 1, 1};
void setup()
{
Serial.begin(9600);
pinMode(button, INPUT);
}
void loop()
{
buttonPressed = digitalRead(button);
if (buttonPressed == HIGH){
counter = count();
//rial.println(counter);
}
else{
Serial.println("Button not pressed");
}
delay(1000);
}
int count()
{
String myString = ""; //Empty string for constructing
int add = 0;
int i = 0;
//Should add all the values from myInts[] into a string
while(i < 8){
myString = String(myString + myInts[i]);
Serial.println(add);
delay(1000);
add++;
i++;
}
Serial.println(myString);
int myNumber = myString.toInt(); //Convert the string to int
Serial.println(myNumber, DEC); //Should print 63 in this case
return add;
}
Your code currently does the following:
Concatenates all your integers together to make a string "00111111"
Attempts to convert it (as a string holding a base 10 integer) to the integer 111,111 (one hundred eleven thousand, one hundred eleven)
Hits integer overflow. The range of an Arduino int is -32768 to 32767 (65536 possible values), so the number you really have is 111111 - 2*65536 = -19961.
I don't believe that there's an overload of Arduino's ToInt that converts a binary string to an integer. Depending on the C++ support in Arduino, you may be able to use std::stoi as described here.
Instead, you may choose to do the conversion yourself - you can keep track of a number sum, and at each loop iteration, double it and then add the next bit:
int sum = 0;
for(int i = 0; i < 8; i++) {
sum *= 2;
sum += myInts[i];
// print and delay if you want
}
Over the eight iterations, sum ought to have values 0, 0, 1, 3, 7, 15, 31, and finally 63
I just bought a 8x32 lattice board (led matrix) and I control it with Arduino. The problem is that I can only use text with the library I got on github. But not numbers, how can I do it?
I'm going to put the code below, the code of the scrolling text and the part of the code in the library that specifies the function used to set the text.
The arduino code that program the scrolling text is here:
#include <HT1632.h>
#include <font_5x4.h>
#include <images.h>
int i = 0;
int wd;
char disp[] = "Hello, how are you?";
int x = 10;
void setup() {
HT1632.begin(A5, A4, A3);
wd = HT1632.getTextWidth(disp, FONT_5X4_END, FONT_5X4_HEIGHT);
}
void loop() {
HT1632.renderTarget(1);
HT1632.clear();
HT1632.drawText(disp, OUT_SIZE - i, 2, FONT_5X4, FONT_5X4_END,
FONT_5X4_HEIGHT);
HT1632.render();
i = (i + 1) % (wd + OUT_SIZE);
delay(100);
}
The library code that specifies the printing of the text is this:
void HT1632Class::drawText(const char text[], int x, int y, const byte font[],
int font_end[], uint8_t font_height,
uint8_t gutter_space) {
int curr_x = x;
char i = 0;
char currchar;
// Check if string is within y-bounds
if (y + font_height < 0 || y >= COM_SIZE)
return;
while (true) {
if (text[i] == '\0')
return;
currchar = text[i] - 32;
if (currchar >= 65 &&
currchar <=
90) // If character is lower-case, automatically make it upper-case
currchar -= 32; // Make this character uppercase.
if (currchar < 0 || currchar >= 64) { // If out of bounds, skip
++i;
continue; // Skip this character.
}
// Check to see if character is not too far right.
if (curr_x >= OUT_SIZE)
break; // Stop rendering - all other characters are no longer within the
// screen
// Check to see if character is not too far left.
int chr_width = getCharWidth(font_end, font_height, currchar);
if (curr_x + chr_width + gutter_space >= 0) {
drawImage(font, chr_width, font_height, curr_x, y,
getCharOffset(font_end, currchar));
// Draw the gutter space
for (char j = 0; j < gutter_space; ++j)
drawImage(font, 1, font_height, curr_x + chr_width + j, y, 0);
}
curr_x += chr_width + gutter_space;
++i;
}
}
You need to look at snprintf. This allows you to format a string of characters just like printf. It allows you to convert something like a int into a part of a string.
an example:
int hour = 10;
int minutes = 50;
char buffer[60];
int status = snprintf(buffer, 60, "the current time is: %i:%i\n", hour, minutes);
buffer now contains:"the current time is: 10:50" (and several empty characters past the \0).
I am trying to run this fast fourier implementation code. It compiles fine but gives this error at runtime. I have no idea about the error or what it means. Can anyone help me out?
I compiled and run the program by:
mpicc -o exec test.c
./exec
CODE:
This is the code that I found on GITHUB. Its the parallel version of fast fourier algorithm.
#include <stdio.h>
#include <mpi.h> //To use MPI
#include <complex.h> //to use complex numbers
#include <math.h> //for cos() and sin()
#include "timer.h" //to use timer
#define PI 3.14159265
#define bigN 16384 //Problem Size
#define howmanytimesavg 3
int main()
{
int my_rank,comm_sz;
MPI_Init(NULL,NULL); //start MPI
MPI_Comm_size(MPI_COMM_WORLD,&comm_sz); ///how many processes are we
using?
MPI_Comm_rank(MPI_COMM_WORLD,&my_rank); //which process is this?
double start,finish;
double avgtime = 0;
FILE *outfile;
int h;
if(my_rank == 0) //if process 0 open outfile
{
outfile = fopen("ParallelVersionOutput.txt", "w"); //open from current
directory
}
for(h = 0; h < howmanytimesavg; h++) //loop to run multiple times for AVG
time.
{
if(my_rank == 0) //If it's process 0 starts timer
{
start = MPI_Wtime();
}
int i,k,n,j; //Basic loop variables
double complex evenpart[(bigN / comm_sz / 2)]; //array to save the data
for EVENHALF
double complex oddpart[(bigN / comm_sz / 2)]; //array to save the data
for ODDHALF
double complex evenpartmaster[ (bigN / comm_sz / 2) * comm_sz]; //array
to save the data for EVENHALF
double complex oddpartmaster[ (bigN / comm_sz / 2) * comm_sz]; //array
to save the data for ODDHALF
double storeKsumreal[bigN]; //store the K real variable so we can abuse
symmerty
double storeKsumimag[bigN]; //store the K imaginary variable so we can
abuse symmerty
double subtable[(bigN / comm_sz)][3]; //Each process owns a subtable
from the table below
double table[bigN][3] = //TABLE of numbers to use
{
0,3.6,2.6, //n, Real,Imaginary CREATES TABLE
1,2.9,6.3,
2,5.6,4.0,
3,4.8,9.1,
4,3.3,0.4,
5,5.9,4.8,
6,5.0,2.6,
7,4.3,4.1,
};
if(bigN > 8) //Everything after row 8 is all 0's
{
for(i = 8; i < bigN; i++)
{
table[i][0] = i;
for(j = 1; j < 3;j++)
{
table[i][j] = 0.0; //set to 0.0
}
}
}
int sendandrecvct = (bigN / comm_sz) * 3; //how much to send and
recieve??
MPI_Scatter(table,sendandrecvct,MPI_DOUBLE,subtable,sendandrecvct,MPI_DOUBLE,0,MPI_COMM_WORLD); //scatter the table to subtables
for (k = 0; k < bigN / 2; k++) //K coeffiencet Loop
{
/* Variables used for the computation */
double sumrealeven = 0.0; //sum of real numbers for even
double sumimageven = 0.0; //sum of imaginary numbers for even
double sumrealodd = 0.0; //sum of real numbers for odd
double sumimagodd = 0.0; //sum of imaginary numbers for odd
for(i = 0; i < (bigN/comm_sz)/2; i++) //Sigma loop EVEN and ODD
{
double factoreven , factorodd = 0.0;
int shiftevenonnonzeroP = my_rank * subtable[2*i][0]; //used to shift index numbers for correct results for EVEN.
int shiftoddonnonzeroP = my_rank * subtable[2*i + 1][0]; //used to shift index numbers for correct results for ODD.
/* -------- EVEN PART -------- */
double realeven = subtable[2*i][1]; //Access table for real number at spot 2i
double complex imaginaryeven = subtable[2*i][2]; //Access table for imaginary number at spot 2i
double complex componeeven = (realeven + imaginaryeven * I); //Create the first component from table
if(my_rank == 0) //if proc 0, dont use shiftevenonnonzeroP
{
factoreven = ((2*PI)*((2*i)*k))/bigN; //Calculates the even factor for Cos() and Sin()
// *********Reduces computational time*********
}
else //use shiftevenonnonzeroP
{
factoreven = ((2*PI)*((shiftevenonnonzeroP)*k))/bigN; //Calculates the even factor for Cos() and Sin()
// *********Reduces computational time*********
}
double complex comptwoeven = (cos(factoreven) - (sin(factoreven)*I)); //Create the second component
evenpart[i] = (componeeven * comptwoeven); //store in the evenpart array
/* -------- ODD PART -------- */
double realodd = subtable[2*i + 1][1]; //Access table for real number at spot 2i+1
double complex imaginaryodd = subtable[2*i + 1][2]; //Access table for imaginary number at spot 2i+1
double complex componeodd = (realodd + imaginaryodd * I); //Create the first component from table
if (my_rank == 0)//if proc 0, dont use shiftoddonnonzeroP
{
factorodd = ((2*PI)*((2*i+1)*k))/bigN;//Calculates the odd factor for Cos() and Sin()
// *********Reduces computational time*********
}
else //use shiftoddonnonzeroP
{
factorodd = ((2*PI)*((shiftoddonnonzeroP)*k))/bigN;//Calculates the odd factor for Cos() and Sin()
// *********Reduces computational time*********
}
double complex comptwoodd = (cos(factorodd) - (sin(factorodd)*I));//Create the second component
oddpart[i] = (componeodd * comptwoodd); //store in the oddpart array
}
/*Process ZERO gathers the even and odd part arrays and creates a evenpartmaster and oddpartmaster array*/
MPI_Gather(evenpart,(bigN / comm_sz / 2),MPI_DOUBLE_COMPLEX,evenpartmaster,(bigN / comm_sz / 2), MPI_DOUBLE_COMPLEX,0,MPI_COMM_WORLD);
MPI_Gather(oddpart,(bigN / comm_sz / 2),MPI_DOUBLE_COMPLEX,oddpartmaster,(bigN / comm_sz / 2), MPI_DOUBLE_COMPLEX,0,MPI_COMM_WORLD);
if(my_rank == 0)
{
for(i = 0; i < (bigN / comm_sz / 2) * comm_sz; i++) //loop to sum the EVEN and ODD parts
{
sumrealeven += creal(evenpartmaster[i]); //sums the realpart of the even half
sumimageven += cimag(evenpartmaster[i]); //sums the imaginarypart of the even half
sumrealodd += creal(oddpartmaster[i]); //sums the realpart of the odd half
sumimagodd += cimag(oddpartmaster[i]); //sums the imaginary part of the odd half
}
storeKsumreal[k] = sumrealeven + sumrealodd; //add the calculated reals from even and odd
storeKsumimag[k] = sumimageven + sumimagodd; //add the calculated imaginary from even and odd
storeKsumreal[k + bigN/2] = sumrealeven - sumrealodd; //ABUSE symmetry Xkreal + N/2 = Evenk - OddK
storeKsumimag[k + bigN/2] = sumimageven - sumimagodd; //ABUSE symmetry Xkimag + N/2 = Evenk - OddK
if(k <= 10) //Do the first 10 K's
{
if(k == 0)
{
fprintf(outfile," \n\n TOTAL PROCESSED SAMPLES : %d\n",bigN);
}
fprintf(outfile,"================================\n");
fprintf(outfile,"XR[%d]: %.4f XI[%d]: %.4f \n",k,storeKsumreal[k],k,storeKsumimag[k]);
fprintf(outfile,"================================\n");
}
}
}
if(my_rank == 0)
{
GET_TIME(finish); //stop timer
double timeElapsed = finish-start; //Time for that iteration
avgtime = avgtime + timeElapsed; //AVG the time
fprintf(outfile,"Time Elaspsed on Iteration %d: %f Seconds\n", (h+1),timeElapsed);
}
}
if(my_rank == 0)
{
avgtime = avgtime / howmanytimesavg; //get avg time
fprintf(outfile,"\nAverage Time Elaspsed: %f Seconds", avgtime);
fclose(outfile); //CLOSE file ONLY proc 0 can.
}
MPI_Barrier(MPI_COMM_WORLD); //wait to all proccesses to catch up before finalize
MPI_Finalize(); //End MPI
return 0;
}
ERROR:
Fatal error in PMPI_Gather: Invalid datatype, error stack:
PMPI_Gather(904): MPI_Gather(sbuf=0x7fffb62799a0, scount=8192,
MPI_DATATYPE_NULL, rbuf=0x7fffb6239980, rcount=8192, MPI_DATATYPE_NULL,
root=0, MPI_COMM_WORLD) failed
PMPI_Gather(815): Datatype for argument sendtype is a null datatype
[unset]: write_line error; fd=-1 buf=:cmd=abort exitcode=537490947
:
system msg for write_line failure : Bad file descriptor
There is no MPI_DATATYPE_NULL in your code, but you only use MPI_DOUBLE_COMPLEX. Note the latter type is a Fortran datatype, and using it in C is not correct strictly speaking.
My guess is that MPI_DOUBLE_COMPLEX is causing the issue (type not defined or not initialized because you invoked the C version of MPI_Init()).
You can obviously rewrite your code in Fortran, or use your own derived datatype for a C double complex number.
Meanwhile, I suggest you write simple C and Fortran helloworld programs that use MPI_DOUBLE_COMPLEX (MPI_Bcast() of one element for example) to confirm the issue is with MPI_DOUBLE_COMPLEX and is restricted to C or not.
My question will be Arduino specific, I wrote a code that turns array of characters (text) into binary string, but the problem is that the binary representation is not 8 bits, its sometimes 7 bits, 6 bits or even 1 bit representation (if you have a value of 1 as decimal). I'm using String constructor String(letter, BIN) to store the binary representation of letter in a string.
I would like to have a 8 bits representation or even a 7 bits representation.
String text = "meet me in university";
String inbits;
byte after;
byte bits[8];
byte x;
char changed_char;
void setup() {
Serial.begin(9600);
}
void loop() {
Serial.println("Press anything to begin");
inbits = convertToBits(text);
}
String convertToBits(String plaintext)
{
String total,temp;
total = String(plaintext[0],BIN);
total = String(total + " ");
for (int i=1;i<plaintext.length();i++)
{
temp = String (plaintext[i],BIN);
total = String(total + temp);
total = String(total + " ");
}
Serial.println(total);
return total;
}
If the length of the argument string is less then 8, prepend "0"s until it is 8 bits long.
You could do something similar to the following:
void PrintBinary(const std::string& test)
{
for (int c = 0; c < test.length(); c++)
{
unsigned bits = (unsigned)test[c];
for (int i = 0; i < 8; i++)
{
std::cout << ((bits >> (7 - i)) & 1U);
}
std::cout << " ";
}
}
Modifying the above example to use String and Serial.println instead of std::string and std::cout should be trivial. I don't own an arduino to test with so I couldn't modify your code and test if the above is possible in the environment you work in but I assume it is.
PrintBinary("Hello"); //Output: 01001000 01100101 01101100 01101100 01101111
String(letter, BIN) doesn't zero pad the string. You have to do it yourself.
You need to prepend the 0 character until your binary string is 8 characters long.
String convertToBits(String plaintext)
{
String total, temp;
total = "";
for (int i=0; i<plaintext.length(); i++)
{
temp = String (plaintext[i], BIN);
while (temp.length() < 8)
temp = '0' + temp;
if (i > 0)
total = String(total + " ");
total = String(total + temp);
}
Serial.println(total);
return total;
}
I am having a trouble in calling the user defined functions in the main program, using unix. the program is executing only for the number generation in the main program. but when i call the predefined function . the output retrieved is incorrect. Can someone please correct me where i have done it wrong
My main program states as
#include <stdio.h>
#include <stdlib.h>
void sort1(int []);
int main(void) {
int array[100];
int i , j;
printf("ten random numbers in [1,1000]\n");
for (i = 1; i <= 10; i++)
{
generate random numbers
}
printf("The list of Hundred random numbers are \n");
for (j = 1; j <= 10; j++ )
{
//to print the random numbers
}
sort1(array);
return 0;
}
//this is my user defined function: sort1.c
include <stdio.h>
int sort1(int a[])
{
int array[100], i, d, swap, e=10;
// algortithm
}
}
printf("Sorted list in ascending order:\n");
for ( i= 0 ; i< e ; i++ )
printf("%d\n", array[i]);
}
I get the output as
ten random numbers in [1,1000]
The list of Hundred random numbers are
--This gives correct output
Sorted list in ascending order:
1
-1442229816
0
-1444472964
#include <stdio.h>
#include <stdlib.h>
void sort1(int []);
int main(void) {
int array[100];
int i;
printf("ten random numbers in [1,1000]\n");
for (i = 1; i <= 10; i++)
{
array[i] = rand()%1000 + 1;
}
printf("The list of Hundred random numbers are \n");
for (i = 1; i <= 10; i++ )
{
printf("Element[%d] = %d\n", i, array[i] );
}
//Up to here it's ok but you have set the values in the positions 1-10 of the array so keep consistent with it
sort1(array);
printf("Sorted list in ascending order:\n");
for ( i= 1 ; i<= 10 ; i++ )
printf("%d\n", array[i]);
return 0;
}
void sort1(int a[])
{
int i,swap,sorted=0;
while(sorted==0){ //flag to know if array is sorted 0 means not sorted.
sorted=1; // we set the flag to sorted at start of sweep
for (i= 1 ; i<= (10-1); i++) //sweep through array
{
if (a[i] > a[i+1]) //check if sorted
{
swap = a[i];
a[i] = a[i+1];
a[i+1] = swap;
sorted=0; //if not sorted set flag to 0 and swap
}
}
}
}
Main problems in your code:
1) array[100] is not initialized in sort1 function.
2) I do not understand your sorting algorithm but in any case you are checking for values of a[0] which are not initialized so take care of the array positions you use each time and be consistent with it.
3) function prototype does not match