Hey guys,
I have a problem when using map() function to map 0 - 1023 to 0 - 5000. I have attached the code and print screen of serial monitor output indicating the error. For the love of god I don't know why this problem occurs. So can anyone help me. Please refer to the print screen of serial monitor for the problem.
Thanks
FSR_1_0.ino (539 Bytes)
For some reason when I changed the code 1 to code 2 i am able to eliminate the issue. So why does this happen?
CODE 1
int fsrPin = 0;
int samples[8];
int i;
int k;void setup()
{
Serial.begin(9600);
pinMode(fsrPin, INPUT);
}void loop()
{
for(i=0; i<=7; i++)
{
samples = analogRead(fsrPin); // sample pin 0, 8 times
_ samples[k] = map(samples*, 0, 1023, 0, 5000); // convert to 5V*_* Serial.print("Analog Reading = ");*
_ Serial.print(samples*,DEC);
Serial.print(", Voltage in mV = ");
Serial.println(samples[k],DEC);
}*_* Serial.println("---------------------------------------");*
* delay (5000);*
}
---------------------------------------------------------------------------------------------------
CODE 2
*int fsrPin = 0; *
int samples[8];
int i;
int k;
void setup()
{
* Serial.begin(9600);*
* pinMode(fsrPin, INPUT);*
}
void loop()
{
* for(i=0; i<=7; i++)*
* {*
_ samples = analogRead(fsrPin); // sample pin 0, 8 times_* Serial.print("Analog Reading = ");*
_ Serial.print(samples*,DEC);*__ samples[k] = map(samples*, 0, 1023, 0, 5000); // convert to 5V*_
* //Serial.print("Analog Reading = ");*
_ //Serial.print(samples*,DEC);
Serial.print(", Voltage in mV = ");
Serial.println(samples[k],DEC);
}*_* Serial.println("---------------------------------------");*
* delay (5000);[/size]*
}[/quote]
samples[k] = map(samples, 0, 1023, 0, 5000); // convert to 5V
Might well not be relevant, but k is an uninitialised int, that never gets a value.
Samples is a pointer.
A constant.
(k is initialised, it was set to zero because it is a global.)
(k is initialised, it was set to zero because it is a global.)
Didn't realise that.
When posting code, use "code" tags, not "quote" tags.
samples = analogRead()
Serial.print(samples,DEC);
samples is an array, so these lines doesn't make sense....
Perhaps you wanted to create a new variable to store the analogRead in, send to map(), and then store in samples*.*
Ok, next time will do, didnt realise there was a button for code, sorry. So what is the problem and what can I do to correct it?
What I want is analog read to read analog data and store in sample [j] and then map sample [j] to sample [k].
int fsrPin = 0;
int samples[8];
int j;
int k;
void setup()
{
Serial.begin(9600);
pinMode(fsrPin, INPUT);
}
void loop()
{
for(j=0; j<=7; j++)
{
samples[j] = analogRead(fsrPin); // sample pin 0, 8 times
Serial.print("Analog Reading = ");
Serial.print(samples[j],DEC);
samples[k] = map(samples[j], 0, 1023, 0, 5000); // convert to 5V
Serial.print(", Voltage in mV = ");
Serial.println(samples[k],DEC);
delay (3000);
}
Serial.println("---------------------------------------");
delay (500);
}
k is still zero.
yaantey:
So what is the problem and what can I do to correct it?
Well, I could repeat myself...
Or here is the same advice I already gave in code (untested):
int fsrPin = 0;
int samples[8];
// no need to globally define j and k, define them when you use them.
void setup()
{
Serial.begin(9600);
pinMode(fsrPin, INPUT);
}
void loop()
{
for(int j=0; j<=7; j++)
{
int currentReading = analogRead(fsrPin);
Serial.print("Analog Reading = ");
Serial.print(currentReading,DEC);
samples[j] = map(currentReading, 0, 1023, 0, 5000); // convert to 5V and save in the array
Serial.print(", Voltage in mV = ");
Serial.println(samples[j],DEC);
delay (3000);
}
Serial.println("---------------------------------------");
delay (500);
}
Edit: removed comment on the array deceleration. I misread the for-loop.
int samples[8]; // 8 is fine, but you only need to set this to 7.
I'd prefer 8, to match the for loop.