Hello to everyone
i am trying to save data in the SDcard
but i have a problem with saving data into the buffer
for a example, v = 10
if i would like to save this value into the buffer
and save into the SDcard that would be 10
how to save into the buffer in the first place ?
Thanks a lot 
Tp little context to give useful answer. Perhaps you could post the code you're having problems with.
i am sorry, here is the code
i have trying to save the value of v that determined by the code
#include <sd-reader_config.h>
#include <sd_raw.h>
#include <sd_raw_config.h>
#include <byteordering.h>
#include <fat.h>
#include <FAT16.h>
#include <fat_config.h>
#include <partition.h>
#include <partition_config.h>
#define FREQ_PIN 3
#include <LiquidCrystal.h>
FAT TestFile; //This will be the file we manipulate in the sketch
char buffer[512]; //Data will be temporarily stored to this buffer before being written to the file
int read_size=0; //Used as an indicator for how many characters are read from the file
int count=0; //Miscellaneous variable
LiquidCrystal lcd(8, 9, 4, 5, 6, 7);
void setup() {
pinMode(FREQ_PIN, INPUT);
lcd.begin(16, 2);
TestFile.initialize();
TestFile.create_file("Velocity Record.txt");
TestFile.open();
}
void loop()
{
unsigned long t1 = pulseIn(FREQ_PIN, HIGH);// Time how long it takes to go HIGH again
unsigned long t2 = pulseIn(FREQ_PIN, LOW); // and how long it takes to go low again.
double t = t1 + t2;
double f = 1000000.0/t;
double w = 2 * 3.14 * f;
double v = w * 0.05;
lcd.setCursor(0,0);
lcd.println(v);
delay(2000);
TestFile.write("The velocity of the wheel"); //using the write function will always write to the beginning of the file.
// Here we add some text to the file.
// Here we add some text to the file.
TestFile.close(); //We are done writing to the file for now. Close it for later use.
while(1)
TestFile.open(); //Open the file. When the file is opened we will be looking at the beginning of the file.
read_size=TestFile.read(buffer); //Read the contents of the file. This will only read the amount of data s
read_size=TestFile.read(buffer); //Read the contents of the file. This will only read the amount of data specified
// by the size of 'buffer.'
sprintf(buffer, "%d", count++); //Now we'll use the buffer to write data back to the file.
// Here's we'll only add one value to buffer, the 'count' variable.
TestFile.write(buffer); //Write the new buffer to the end of the file
TestFile.close(); //Close the file for later use.
delay(1000); //Wait one second before repeating the loop.
}
it is showing this error
C:\Users\Max\Documents\Arduino\Arduino\arduino-0018\libraries\SDcard/sd_raw_config.h:86:6: error: #error "no sd/mmc pin mapping available!"
C:\Users\Max\Documents\Arduino\Arduino\arduino-0018\libraries\FAT/fat.h:89: error: 'offset_t' does not name a type
C:\Users\Max\Documents\Arduino\Arduino\arduino-0018\libraries\FAT/fat.h:117: error: 'offset_t' does not name a type
C:\Users\Max\Documents\Arduino\Arduino\arduino-0018\libraries\FAT/fat.h:118: error: 'offset_t' does not name a type
C:\Users\Max\Documents\Arduino\Arduino\arduino-0018\libraries\FAT/partition.h:83: error: typedef 'device_read_t' is initialized (use typeof instead)
C:\Users\Max\Documents\Arduino\Arduino\arduino-0018\libraries\FAT/partition.h:83: error: 'offset_t' was not declared in this scope
C:\Users\Max\Documents\Arduino\Arduino\arduino-0018\libraries\FAT/partition.h:83: error: expected primary-expression before '*' token
C:\Users\Max\Documents\Arduino\Arduino\arduino-0018\libraries\FAT/partition.h:83: error: 'buffer' was not declared in this scope
C:\Users\Max\Documents\Arduino\Arduino\arduino-0018\libraries\FAT/partition.h:83: error: expected primary-expression before 'length'
C:\Users\Max\Documents\Arduino\Arduino\arduino-0018\libraries\FAT/partition.h:92: error: 'offset_t' has not been declared
C:\Users\Max\Documents\Arduino\Arduino\arduino-0018\libraries\FAT/partition.h:111: error: typedef 'device_read_interval_t' is initialized (use typeof instead)
C:\Users\Max\Documents\Arduino\Arduino\arduino-0018\libraries\FAT/partition.h:111: error: 'offset_t' was not declared in this scope
C:\Users\Max\Documents\Arduino\Arduino\arduino-0018\libraries\FAT/partition.h:111: error: expected primary-expression before '*' token
C:\Users\Max\Documents\Arduino\Arduino\arduino-0018\libraries\FAT/partition.h:111: error: 'buffer' was not declared in this scope
C:\Users\Max\Documents\Arduino\Arduino\arduino-0018\libraries\FAT/partition.h:111: error: expected primary-expression before 'interval'
C:\Users\Max\Documents\Arduino\Arduino\arduino-0018\libraries\FAT/partition.h:111: error: expected primary-expression before 'length'
C:\Users\Max\Documents\Arduino\Arduino\arduino-0018\libraries\FAT/partition.h:111: error: expected primary-expression before 'callback'
C:\Users\Max\Documents\Arduino\Arduino\arduino-0018\libraries\FAT/partition.h:111: error: expected primary-expression before 'void'
C:\Users\Max\Documents\Arduino\Arduino\arduino-0018\libraries\FAT/partition.h:119: error: typedef 'device_write_t' is initialized (use typeof instead)
C:\Users\Max\Documents\Arduino\Arduino\arduino-0018\libraries\FAT/partition.h:119: error: 'offset_t' was not declared in this scope
C:\Users\Max\Documents\Arduino\Arduino\arduino-0018\libraries\FAT/partition.h:119: error: expected primary-expression before 'const'
C:\Users\Max\Documents\Arduino\Arduino\arduino-0018\libraries\FAT/partition.h:119: error: expected primary-expression before 'length'
C:\Users\Max\Documents\Arduino\Arduino\arduino-0018\libraries\FAT/partition.h:129: error: 'offset_t' has not been declared
C:\Users\Max\Documents\Arduino\Arduino\arduino-0018\libraries\FAT/partition.h:148: error: typedef 'device_write_interval_t' is initialized (use typeof instead)
C:\Users\Max\Documents\Arduino\Arduino\arduino-0018\libraries\FAT/partition.h:148: error: 'offset_t' was not declared in this scope
C:\Users\Max\Documents\Arduino\Arduino\arduino-0018\libraries\FAT/partition.h:148: error: expected primary-expression before '*' token
C:\Users\Max\Documents\Arduino\Arduino\arduino-0018\libraries\FAT/partition.h:148: error: 'buffer' was not declared in this scope
C:\Users\Max\Documents\Arduino\Arduino\arduino-0018\libraries\FAT/partition.h:148: error: expected primary-expression before 'length'
C:\Users\Max\Documents\Arduino\Arduino\arduino-0018\libraries\FAT/partition.h:148: error: expected primary-expression before 'callback'
C:\Users\Max\Documents\Arduino\Arduino\arduino-0018\libraries\FAT/partition.h:148: error: expected primary-expression before 'void'
C:\Users\Max\Documents\Arduino\Arduino\arduino-0018\libraries\FAT/partition.h:161: error: 'device_read_t' does not name a type
C:\Users\Max\Documents\Arduino\Arduino\arduino-0018\libraries\FAT/partition.h:168: error: 'device_read_interval_t' does not name a type
C:\Users\Max\Documents\Arduino\Arduino\arduino-0018\libraries\FAT/partition.h:175: error: 'device_write_t' does not name a type
C:\Users\Max\Documents\Arduino\Arduino\arduino-0018\libraries\FAT/partition.h:182: error: 'device_write_interval_t' does not name a type
C:\Users\Max\Documents\Arduino\Arduino\arduino-0018\libraries\FAT/partition.h:200: error: 'device_read_t' was not declared in this scope
C:\Users\Max\Documents\Arduino\Arduino\arduino-0018\libraries\FAT/partition.h:200: error: 'device_read_interval_t' was not declared in this scope
C:\Users\Max\Documents\Arduino\Arduino\arduino-0018\libraries\FAT/partition.h:200: error: 'device_write_t' was not declared in this scope
C:\Users\Max\Documents\Arduino\Arduino\arduino-0018\libraries\FAT/partition.h:200: error: 'device_write_interval_t' was not declared in this scope
C:\Users\Max\Documents\Arduino\Arduino\arduino-0018\libraries\FAT/partition.h:200: error: expected primary-expression before 'index'
C:\Users\Max\Documents\Arduino\Arduino\arduino-0018\libraries\FAT/partition.h:200: error: initializer expression list treated as compound expression
In function 'void setup()':
Bad error line: -2