[SOLVED]Arduino Uno, Gameduino2 and ADS1298 (SPI issue)

[borjavr]

Hi everybody!

I´m using this three devices, communicating through SPI: Arduino Uno, Gameduino2 and ADS1298 (analog to digital converter)
The idea is to build an electrocardiograph. ADS registers values from electrodes, converts, sends to Arduino and Arduino sends to Gameduino2 to plot data, but I have some problems.
Here is my code (some things not necesary deleted to make it more readable).

#include <SPI.h>
#include <EEPROM.h>
#include <GD2.h>

//Pin configuration
const int CS_GD_pin = 8;
const int CS_ADS_pin = A5; 
const int MOSI_pin = 11;
const int MISO_pin = 12;
const int SCK_pin = 13;


void setup() {

    //Pin settings
    pinMode(CS_GD_pin, OUTPUT);
    digitalWrite(CS_GD_pin, HIGH);
    pinMode(CS_ADS_pin, OUTPUT);
    digitalWrite(CS_ADS_pin, HIGH);


    pinMode(MOSI_pin, OUTPUT);
    pinMode(MISO_pin, INPUT);
    pinMode(SCK_pin, OUTPUT);
    pinMode(ADSReset_pin,OUTPUT);

    GD.begin();
}

void loop() {

    plot();

    ADS_ready();

    attachInterrupt(ADSInterrupt, read_subfunction, FALLING);
    delay(100);
    detachInterrupt(ADSInterrupt);
    digitalWrite(CS_ADS_pin, HIGH);
}


void plot() {

    digitalWrite(CS_GD_pin, LOW);
         //Here plotting code which is basically (for the moment) an order to plot the matrix, with GD.Begin(POINTS) and GD.Vertex2ii...
    digitalWrite(CS_GD_pin, HIGH);
}

void ADS_ready() {

    digitalWrite(CS_ADS_pin, LOW);
    //Initialize SPI for ADS
        SPI.begin();
        SPI.setDataMode(SPI_MODE1);
        SPI.setBitOrder(MSBFIRST);
        SPI.setClockDivider(SPI_CLOCK_DIV8);

    //Here some ADS settings
}

void read_subfunction(){

    //Here reading code, when ADS says new data are ready the interrupt is activated and Arduino enters this ISR and stores data into a matrix
}

Some important points: 

• I change SPI_MODE "on the fly" because it´s mandatory, devices' need.
• As you can see every part of the code related to ADS is wraped around CS_ADS_pin setting, and idem for Gameduino2 
• The ADS part works fine (checked with Matlab)
• Gameduino part does not work. If I put a counter inside plot() I can see the program enters, but it´s like it only swaps for the first time. For example, if inside plot() I forget about the matrix and build a little program to display a counter on the screen with one second delay (1,2,3...) it only plots 1.

I think there is a problem with the Gameduino2 SlaveSelect pin (8, CS_GD_pin in my program). I tried with GD.__end(), GD.resume() and so, I admit I don´t understand very well Gameduino libraries because I´m not an expert at all, so any help is gladly appreciate!

[borjavr]

I have been trying and I got to make it better, the only line of my program that´s causing a problem on the rest is when I set SPI_MODE to 1 before I communicate with ADS (inside ADS_ready function). If I delete that line Gameduino2 works fine (but of course I´m not reading data). Does anyone know about how to improve stability of the sistem when you change SPI settings "on the fly" or something related?

Thanks!

[jamesbowman]

Well, one of the things that the Gameduino 2 library does is continuous SPI writes. So the GD2 is still selected between calls to the GD library.

So to talk to some other SPI device you need to:

GD.__end();
// change SPI
// talk to device
// restore SPI
GD.resume();

This should work much better.

[borjavr]

Hi James, thanks for the reply!

I tried what you advise, unfortunately it doesn´t fix it completely, the screen kind of saturates/floods, white lines on my green background blink and I can´t watch data. The only problem seems to be to change the SPI mode, because if I //comment that line the screen works fine (and I can see some points moving on it because the matrix may have some random values), but of course, it´s not real data...
I´ll keep trying and search deeper in the forum for this specific trouble, and if anybody has any idea or a similar problem has been overcome I appreciate your answers of course!

Thanks

[jamesbowman]

So -- just to be clear -- now you have something like this:

GD.__end();
// change SPI
SPI.setDataMode(SPI_MODE1);
...
// talk to device
...

// restore SPI
SPI.setDataMode(SPI_MODE0);
SPI.setClockDivider(SPI_CLOCK_DIV2);

GD.resume();

[borjavr]

I got the solution! I "only" needed to change the SPI mode BEFORE selecting the slaves, and not after, as I was doing. I read about it on the Arduino Forum. So I have:

GD.__end();
// change SPI
SPI.setDataMode(SPI_MODE1);
//NOW select the device
digitalWrite(SS_ADS_pin, LOW);
...
talk to device
...
digitalWrite(SS_ADS_pin, HIGH);
//restore SPI
SPI.setDataMode(SPI_MODE0);
SPI.setClockDivider(SPI_CLOCK_DIV2);

GD.resume();

It works. In the Forum I also read something about slowing down the SPI bus and so, maybe to optimize the process. But for the moment is enough for me.
I think it was happening something similar to when you call GD.begin() in the loop(), it floods or something (I don´t know if I´m right, but it´s my
idea based on my observation).
Thanks a lot for the help!! I will keep trying changes and if I improve I will write here. I hope it´s useful for other people.

[hojjat]

hello Mr. borjavr

i am student of biomedical engineering.
i read "Arduino Uno, Gameduino2 and ADS1298 (SPI issue)" project of you.

I'm asking you that, if possible, to send the above project files to me.
As much as I need it

Thank you very much for your kindness
Hojjat fallah