I am an undergraduate student at a public university in Maryland. I am currently doing a project with an arduino and I came across a problem that I could not figure out after several days of researching. Regarding my project, I am trying to collect 6 data (acceleration and gyration in x,y,z) from an accelerometer/gyroscope sensor at a desired constant rate (trying to make it 1000 Hz, so about 1000 sets of the 6 data per second) into a SD card. However, I could not make the arduino do this; I am able to collect the data, but not at a constant sampling frequency of 1000 Hz. Could someone help me set the sampling frequency at 1000 Hz please. Here are some of the information of the sensors and arduino I am using:
- Arduino nano
- MPU-6050 gy-521 accelerometer/gyroscope - http://playground.arduino.cc/Main/MPU-6050
- SD card reader - http://www.aliexpress.com/item/SD-Card-Reader-Module-for-Arduino-ARM-Read-and-Write-Free-shipping/526750081.html?spm=2114.12010108.1000023.4.JkncUu&spm=2114.12010108.1000023.4.JkncUu
Also, I have posted my code. Thank you in advance for the help.
My code:
#include <Wire.h>
#include <LiquidCrystal.h>
#include <SPI.h>
#include <SD.h>
unsigned long time;
#include "I2Cdev.h"
#include "MPU6050.h"
MPU6050 accelgyro;
#define OUTPUT_READABLE_ACCELGYRO
const int sdcard = 7;
int num;
int16_t ax,ay,az,gx,gy,gz;
LiquidCrystal lcd(10, 9, 5, 4, 3, 2); //12 is 10 and 11 is 9
void setup()
{
Serial.begin(115200);
lcd.begin(16, 2);
pinMode(8, INPUT_PULLUP);
Serial.print("Initializing SD card...");
if (!SD.begin(sdcard))
{
Serial.println("initialization failed!");
return;
}
Serial.println("initialization done.");
accelgyro.initialize();
}
void loop()
{
lcd.setCursor(0,0);
lcd.print("Push button");
lcd.setCursor(0,1);
lcd.print("to start");
int sensorVal = digitalRead(8);
if (sensorVal == 0)
{
delay(500);
num = 1;
collect();
}
}
void collect()
{
File myFile = SD.open("test.txt",FILE_WRITE);
myFile.println("Begin:");
myFile.print("x-axis ");
myFile.print("y-axis ");
myFile.print("z-axis ");
myFile.print("\n");
Serial.println("Begin:");
Serial.print("x-axis: ");
Serial.print("\t");
Serial.print("y-axis: ");
Serial.print("\t");
Serial.print("z-axis: ");
Serial.print("\n");
if(myFile)
{
while (num == 1)
{
accelgyro.getMotion6(&ax, &ay, &az, &gx, &gy, &gz);
lcd.setCursor(0,0);
lcd.print((double) ax/16384*9.81);
lcd.setCursor(7,0);
lcd.print((double) ay/16384*9.81);
lcd.setCursor(0,1);
lcd.print((double) az/16384*9.81);
lcd.setCursor(7,1);
lcd.print(time);
time = millis();
Serial.print("Time: ");
Serial.println(time);
Serial.print(ax);
Serial.print("\t");
Serial.print((double) ax/16384*9.81);
Serial.print("\t");
Serial.print(ay);
Serial.print("\t");
Serial.print((double) ay/16384*9.81);
Serial.print("\t");
Serial.print(az);
Serial.print("\t");
Serial.print((double) az/16384*9.81);
Serial.print("\n");
myFile.print("Time: ");
myFile.println(time);
myFile.print(ax);
myFile.print("\t");
myFile.print(ay);
myFile.print("\t");
myFile.println(az);
int sensorVal = digitalRead(8);
if(sensorVal == 0)
{
delay(500);
num = 0;
Serial.println("STOPPED");
myFile.println("STOPPED");
Serial.print("\n");
myFile.print("\n");
myFile.close();
lcd.clear();
lcd.setCursor(0,0);
lcd.print("Stopped");
delay(2000);
}
}
}
}
