//
// Made for Spikerling board V0.4
// 18. August 2022
// BackyardBrains
// Inputs:
//        - light sensor
//        - analog input jack (0-5V)
//
// Outputs:
//        - analog output of V on jack
//        - click sound whenever V crosses 50mV
//        - TTL pulse whenever V crosses 50mV
//        - serial communication @ 2Mbaud (text values of V)


//Reversal potentials
double EK = -84; //mV
double ECa = 120; //mV
double EL = -60; //mV
double Cm = 1.0; //microF/cm2
//Time step
double  dt = 0.0001;

//Maximal conductances
double gL = 2; //mS/cm2
double gK = 8;
double gCa = 4;
double gKCa = 0.75;


// Other params
double V1 = -1.2;
double V2 = 18;
double V3 = 12;
double V4 = 17.4;
double phi = 4.6;
double eps = 0.07;
double kCa = 1.0;
double mu = 0.02;
double Iapp = 55;
double V = 0;
double n = 0;
double Ca = 0;

double minf;
double tau_n;
double ninf;
double z;
double IKCa;

void setup()
{
  Serial.begin(2000000);
}

void loop() {

    // put your main code here, to run repeatedly:
    minf = 0.5*(1+tanh((V-V1)/V2));
    tau_n = 1.0/cosh((V-V3)/(2*V4));
    ninf = 0.5*(1+tanh((V-V3)/V4));
    z = Ca/(Ca+1);
    IKCa = gKCa*z*(V-EK);
    V = V + ((-gL*(V-EL) - gK*n*(V-EK) - gCa*minf*(V-ECa)-IKCa +Iapp)/Cm)*dt;
    n = n + phi*((ninf-n)/tau_n)*dt;
    Ca = Ca + eps*(-mu*(gCa*minf*(V-ECa))-kCa*Ca)*dt;

    Serial.print("Variable 1:");
    Serial.println(V);
    // Serial.print(",");
    //Serial.println(Iapp);
    /*
    Serial.print(gKCa);
    Serial.print(",");
    Serial.print(gK);
    Serial.print(",");
    Serial.print(gCa);
    Serial.print(",");
    Serial.print(Ca);
    Serial.print("%");
    */
    //Serial studio output
    /*
    Serial.print("%");
    Serial.print(V);
    Serial.print(",");
    Serial.print(gKCa);
    Serial.print(",");
    Serial.print(gK);
    Serial.print(",");
    Serial.print(gCa);
    Serial.print(",");
    Serial.print(Ca);
    Serial.print("%");
    */
}