I have a question about coding. how is it possible to pull a single data value from a stream of data? I have a pressure transducer that is set to continuously output pressure readings at a frequency of 10Hz. I can successfully the data stream with my Arduino Pro Micro, but I lack the ability to read a single value and store it as a char variable. Here is the code I am using.
Below is an image of the data stream from the pressure transducer, read through the Arduino. How can I pull just one of those values like *000114.4929 out?
I have a question about coding. how is it possible to pull a single data value from a stream of data?
How would you pick a single fish out of a stream? You'd have to detect when its snout passed by, and when its tail passed by, so you'd know when to collect fish, without collecting water.
char data = "";
You can NOT store a string in a char.
Single quotes are for single characters. Double quotes are for strings.
I want to say thanks again for the help. Robin2, your page Serial Input Basics was very helpful for me. I was able to get the Arduino to read the sensor data and store each in an array, then print them out to the Serial Monitor. I followed your example with the start and end markers. Now I am getting output like this:
000114.2927
000114.2928
000114.2926
And this is the code I am using:
#include <SoftwareSerial.h>
#define paroRX 8
#define paroTX 9
SoftwareSerial paroSerial(paroRX, paroTX);
const byte numChars = 16;
char paroChars[numChars]; //array to store received data
char paroToSend[numChars]; //array to transmit
boolean newParoData = false;
void setup(){
Serial.begin(9600); //with transmitter radio
paroSerial.begin(9600);
}
void loop(){
paroSerial.listen();
readParo(); //read from Paro and store values in paroChars
if(newParoData == true){
for(int i=0; i<16; i++){
paroToSend[i] = paroChars[i];
}
Serial.print(paroToSend); Serial.print('\n'); //transmit Paro data with a new line for each value
newParoData = false;
}
}
void readParo(){
static boolean receiveInProgress = false;
static byte index = 0;
char startMarker = '*';
char endMarker = '\n';
char pd;
while(paroSerial.available() && newParoData == false){
pd = paroSerial.read();
if(receiveInProgress == true){
if(pd != endMarker){
paroChars[index] = pd;
index++;
if(index >= numChars){
index = numChars - 1;
}
}else{
paroChars[index] = '\0'; //terminate string
receiveInProgress = false;
index = 0;
newParoData = true;
}
}else if(pd == startMarker){
receiveInProgress = true;
}
}
}
I have another related question. The sensor is programmed to continuously output data at a frequency of 10Hz. With my code, the Arduino seems also to read and print at 10Hz. How can I read and print a data value just once every second? The obvious choice to me was to put a delay in the loop, but after trying delay(1000) and using the millis() function, I get distorted readings. Although they do print at 1Hz to the Serial Monitor.
#include <SoftwareSerial.h>
#define paroRX 8
#define paroTX 9
SoftwareSerial paroSerial(paroRX, paroTX);
const byte numChars = 16;
char paroChars[numChars]; //array to store received data
char paroToSend[numChars]; //array to transmit
boolean newParoData = false;
void setup(){
Serial.begin(9600); //with transmitter radio
paroSerial.begin(9600);
}
void loop(){
paroSerial.listen();
readParo(); //read from Paro and store values in paroChars
if(newParoData == true){
for(int i=0; i<16; i++){
paroToSend[i] = paroChars[i];
}
Serial.print(paroToSend); Serial.print('\n'); //transmit Paro data with a new line for each value
newParoData = false;
}
delay(1000);
}
void readParo(){
static boolean receiveInProgress = false;
static byte index = 0;
char startMarker = '*';
char endMarker = '\n';
char pd;
while(paroSerial.available() && newParoData == false){
pd = paroSerial.read();
if(receiveInProgress == true){
if(pd != endMarker){
paroChars[index] = pd;
index++;
if(index >= numChars){
index = numChars - 1;
}
}else{
paroChars[index] = '\0'; //terminate string
receiveInProgress = false;
index = 0;
newParoData = true;
}
}else if(pd == startMarker){
receiveInProgress = true;
}
}
}
With this code, I get this kind of output on the Serial Monitor:
000114.4927
***000114.4948
***000114
4947
*000114
What is my problem here? How can I read at a specified frequency of 1Hz when I have a continuous stream of data?
If the device outputs 10 values per second, and you only want to display/deal with every 10th value, it doesn't seem overly complicated to determine if this value is the 10th value, and so should be used (and the counter reset), or not.
