K617

                   // GPIB Pin
                   //     Description
#define EOI  A5    // 05  End-or-Identify
#define DAV  A4    // 06  Data Valid
#define NRFD A3    // 07  Not ready for data
#define NDAC 12    // 08  Not data accepted
#define IFC  11    // 09  Interface clear
#define SRQ  A2    // 10  Service request
#define ATN  A1     // 11  Attention
#define REN  10     // 17  Remote enable

#define DIO1 2     // 01  Data IO 1 LSB
#define DIO2 3     // 02  Data IO 2
#define DIO3 4     // 03  Data IO 3
#define DIO4 5     // 04  Data IO 4
#define DIO5 6     // 13  Data IO 5
#define DIO6 7     // 14  Data IO 6
#define DIO7 8     // 15  Data IO 7
#define DIO8 9     // 16  Data IO 8 MSB

#define TIMEOUT 300000

void setup()
{
    Serial.begin(9600);

    pinMode(ATN, OUTPUT);
    digitalWrite(ATN, HIGH);
}

// Main program loop
void loop()
{
    Serial.print(readByte());
}

char readByte()
{
    pinMode(NRFD, OUTPUT);
    pinMode(NDAC, OUTPUT);

    digitalWrite(NRFD, HIGH);
    digitalWrite(NDAC, LOW);

    waitUntil(DAV, LOW);
    digitalWrite(NRFD, LOW);

    char data = getData();

    digitalWrite(NDAC, HIGH);

    waitUntil(DAV, HIGH);
    digitalWrite(NDAC, LOW);

    return data;
}

bool waitUntil(int port, int status)
{
    unsigned long t = millis();
    while (digitalRead(port) != status)
    {
        if (millis() - t > TIMEOUT)
        {
            errorTimeout(port, status);
            return false;
        }
    }
    return true;
}

void errorTimeout(int port, int status)
{
    Serial.print("Error timeout: ");
    Serial.print(port);
    Serial.print(" ");
    Serial.println(status);
    Serial.println("Restart microcontroller");

    while (true) {}
}

char getData()
{
    pinMode(DIO1, INPUT);
    pinMode(DIO2, INPUT);
    pinMode(DIO3, INPUT);
    pinMode(DIO4, INPUT);
    pinMode(DIO5, INPUT);
    pinMode(DIO6, INPUT);
    pinMode(DIO7, INPUT);
    pinMode(DIO8, INPUT);

    char dataA = 0;
    char dataB = 0;

    dataB = bitWrite(dataA, 0, digitalRead(DIO1));
    dataA = bitWrite(dataB, 1, digitalRead(DIO2));
    dataB = bitWrite(dataA, 2, digitalRead(DIO3));
    dataA = bitWrite(dataB, 3, digitalRead(DIO4));
    dataB = bitWrite(dataA, 4, digitalRead(DIO5));
    dataA = bitWrite(dataB, 5, digitalRead(DIO6));
    dataB = bitWrite(dataA, 6, digitalRead(DIO7));
    dataA = bitWrite(dataB, 7, digitalRead(DIO8));

    return ~dataA;
}