I have a very similar problem as this guy Data Logger Shield Gone Haywire (Arduino Brain Library) - Programming Questions - Arduino Forum ; however, it does not look like that was solved.
Project: I want to use an arduino to connect a toy eeg and log all of the data to a micro sd card. I am using the eeg from this tutorial How to Hack Toy EEGs | Frontier Nerds . It works perfectly on it's own. I am using a microSD card with a simple breakout from sparkfun SparkFun microSD Transflash Breakout - BOB-00544 - SparkFun Electronics. It also works perfectly on it's own
Problem: When I try to merge both of them together, it does not work. I have narrowed the problem down to one thing. On the eeg module, when the code calls brain.update() it returns false and not true.
BTW eeg returns a char, in my code a casted it to a string
So I think there is something in these libraries that are conflicting with each other, I am just not sure what.
Code for just the eeg (example from the library)
// Arduino Brain Library - Brain Serial Test
// Description: Grabs brain data from the serial RX pin and sends CSV out over the TX pin (Half duplex.)
// More info: https://github.com/kitschpatrol/Arduino-Brain-Library
// Author: Eric Mika, 2010 revised in 2014
#include <Brain.h>
// Set up the brain parser, pass it the hardware serial object you want to listen on.
Brain brain(Serial);
void setup() {
// Start the hardware serial.
Serial.begin(9600);
}
void loop() {
// Expect packets about once per second.
// The .readCSV() function returns a string (well, char*) listing the most recent brain data, in the following format:
// "signal strength, attention, meditation, delta, theta, low alpha, high alpha, low beta, high beta, low gamma, high gamma"
if (brain.update()) {
Serial.println(brain.readErrors());
Serial.println(brain.readCSV());
}
}
Code with just the SD card also just example
/*
SD card datalogger
This example shows how to log data from three analog sensors
to an SD card using the SD library.
The circuit:
* analog sensors on analog ins 0, 1, and 2
* SD card attached to SPI bus as follows:
** MOSI - pin 11
** MISO - pin 12
** CLK - pin 13
** CS - pin 4
created 24 Nov 2010
modified 9 Apr 2012
by Tom Igoe
This example code is in the public domain.
*/
#include <SD.h>
// On the Ethernet Shield, CS is pin 4. Note that even if it's not
// used as the CS pin, the hardware CS pin (10 on most Arduino boards,
// 53 on the Mega) must be left as an output or the SD library
// functions will not work.
const int chipSelect = 10;
void setup()
{
// Open serial communications and wait for port to open:
Serial.begin(9600);
while (!Serial) {
; // wait for serial port to connect. Needed for Leonardo only
}
Serial.print("Initializing SD card...");
// make sure that the default chip select pin is set to
// output, even if you don't use it:
pinMode(10, OUTPUT);
// see if the card is present and can be initialized:
if (!SD.begin(chipSelect)) {
Serial.println("Card failed, or not present");
// don't do anything more:
return;
}
Serial.println("card initialized.");
}
void loop()
{
// make a string for assembling the data to log:
String dataString = "This is a test. Jacob stein ";
// open the file. note that only one file can be open at a time,
// so you have to close this one before opening another.
File dataFile = SD.open("datalog.txt", FILE_WRITE);
// if the file is available, write to it:
if (dataFile) {
dataFile.println(dataString);
dataFile.close();
// print to the serial port too:
Serial.println(dataString);
}
// if the file isn't open, pop up an error:
else {
Serial.println("error opening datalog.txt");
}
}
Combined code, modified for debugging. It returns "the head does not work" but it successfully writes to the micro sd card.
#include <SD.h>
#include <Brain.h>
Brain brain(Serial);
const int chipSelect = 10;
String dataToWrite;
void setup(){
Serial.begin(9600);
Serial.println("Initializing SD...");
pinMode(chipSelect,OUTPUT);
if (!SD.begin(chipSelect)){
Serial.println("Card failed!!!");
return;
}
Serial.println("Card Initialized.");
}
void loop(){
if (brain.update()) {
Serial.println(brain.readErrors());
Serial.println(brain.readCSV());
}
else
{
Serial.println("The Head does not work");
}
File dataFile = SD.open("testtest.txt",FILE_WRITE);
if(dataFile ){
dataFile.println("hello");
dataFile.close();
Serial.print("Wrote to the SD: ");
Serial.println("hello");
}
else{
Serial.println("Couldn't make file!!!");
}
delay(2000);
}
Earlier I had one if statement check if( brain.update() && dataFile) and then add the brain.readcsv() to the file. It wouldnt go into the body of the if statement though.