Arduino DO sensor via Arduino Mega 2560 & ladyAda Datalogger

hello,
     i need adjusting code can

a) map 1023 0-255 scale
b) multiply results of potentiometers 0.68966
c) record , display in serial monitor , datalog file on datalogger


here is: /*
  sd card datalogger

   
circuit:
* analog sensors on analog ins 0, 1, , 2
* sd card attached spi bus follows:
** mosi - pin 11
** miso - pin 12
** clk - pin 13
** cs - pin 4

     
*/

#include <sd.h>

// on ethernet shield, cs pin 4. note if it's not
// used cs pin, hardware cs pin (10 on arduino boards,
// 53 on mega) must left output or sd library
// functions not work.
const int chipselect = 10;

void setup()
{
// open serial communications , wait port open:
  serial.begin(9600);
  analogreference(internal1v1);
   while (!serial) {
    ; // wait serial port connect. needed leonardo only
  }


  serial.print("initializing sd card...");
  // make sure default chip select pin set to
  // output, if don't use it:
  pinmode(53, output);
 
  // see if card present , can initialized:
  if (!sd.begin(chipselect)) {
    serial.println("card failed, or not present");
    // don't more:
    return;
  }
  serial.println("card initialized.");
}

void loop()
{
  // make string assembling data log:
  string datastring = "";
 
  // read 3 sensors , append string:
  (int analogpin = 0; analogpin < 3; analogpin++) {
    int sensor = analogread(analogpin);
    datastring += string(sensor);
    if (analogpin < 2) {
      datastring += ",";
    }
    delay(500);
  }

  // open file. note 1 file can open @ time,
  // have close 1 before opening another.
  file datafile = sd.open("datalog.txt", file_write);

  // if file available, write it:
  if (datafile) {
   
    datafile.println(datastring);
    datafile.close();
    // print serial port too:
    serial.println(datastring);
  } 
  // if file isn't open, pop error:
  else {
    serial.println("error opening datalog.txt");
  }
}




thank you

quote

a) map 1023 0-255 scale

otherwise known divide 4.

quote

b) multiply results of potentiometers 0.68966

there handy * operator.

quote

c) record , display in serial monitor , datalog file on datalogger

that code (poorly). need?

Arduino Forum > Using Arduino > Project Guidance > Arduino DO sensor via Arduino Mega 2560 & ladyAda Datalogger

arduino