Forgive mt stupidity... I'm very much a learner.
I am sending a sequence of numbers by serial from the my computer.
I need to then store the sequence as a long integer.
So if I send 54321 which begin their life as a sequence ascii characters. How do I put them together in the arduino so i end up with a long int = 54321 ?
Would a kind soul be able to help me out here.
Embarrisingly frustrated with the hours I've been playing around trying to solve this seeming simple task.
Cheers muchly
You'll have to make at least one change (i = 0 should be i = 0L) to support long ints, but this is a function I wrote. It echoes and checks for validity. Looking at the code at this late date, I'm not sure why I made c and i static...
int read_int()
{
static byte c;
static int i;
i = 0;
while (1)
{
while (!Serial.available())
{;}
c = Serial.read();
Serial.print(c, BYTE);
if (c == '\r')
{
Serial.print(crlf);
return i;
}
if (isdigit(c))
{
i = i * 10 + c - '0';
}
else
{
Serial.print("\r\nERROR: \"");
Serial.print(c, BYTE);
Serial.print("\" is not a digit\r\n");
return -1;
}
}
}
-j
Thank you very much :)!
You'll have to make at least one change (i = 0 should be i = 0L) to support long ints, but this is a function I wrote. It echoes and checks for validity. Looking at the code at this late date, I'm not sure why I made c and i static...
int read_int()
{
static byte c;
static int i;
i = 0;
while (1)
{
while (!Serial.available())
{;}
c = Serial.read();
Serial.print(c, BYTE);
if (c == '\r')
{
Serial.print(crlf);
return i;
}
if (isdigit(c))
{
i = i * 10 + c - '0';
}
else
{
Serial.print("\r\nERROR: "");
Serial.print(c, BYTE);
Serial.print("" is not a digit\r\n");
return -1;
}
}
}
-j
I'm trying to reuse some of this logic, but it looks like there's a static variable "crlf" that's undefined, and a function "isdigit" that's not defined. Any clues?
Answered my own question. Found it in another post. For anyone else who has a prob:
#define isdigit(X) (((X) >= '0') && ((X) <= '9'))
char crlf[] = "\r\n";
Don't know if this will help or if you already figured it out - but I recently spent a unexpected long, painful day at this (if I had known it was going to be hard I would have braced myself...)
Probably better ways to do it but this worked for me:
On the sending end:
byte1 = integer(num/16777216)
num=num-(byte1*16777216)
byte2 = integer(num/65536)
num = num-(byte2*65536)
byte3 = integer(num/256)
byte4 = num-(byte3*256)
Send those, followed by sending "*"
On the receiving end:
int getInput(){
int total = 0;
int byteCount = 1;
int val;
while(1){
while (Serial.available() > 0) {
val = Serial.read();
if (val == '*'){
return total;
}
else {
switch(byteCount){
case 1:
total = total + (val * 16777216);
byteCount++;
break;
case 2:
total = total + (val * 65536);
byteCount++;
break;
case 3:
total = total + (val * 256);
byteCount++;
break;
case 4:
total = total + val;
break;
}
}
}
}
}
Probably better ways to do it but this worked for me:
On the sending end:
byte1 = integer(num/16777216)
num=num-(byte116777216)
byte2 = integer(num/65536)
num = num-(byte265536)
byte3 = integer(num/256)
byte4 = num-(byte3*256)
A more intuitive approach might be to use bitshifting, so it's clear what's going on:
byte4 = num & 0xFF; // least significant byte of the long "num"
byte3 = (num >> 8) & 0xFF;
byte2 = (num >> 16) & 0xFF;
byte1 = num >> 24; // most significant byte of the long "num"
You could even pretty easily embed it in a for loop if so desired.