Datasheet

For more on integer constants in the different number bases, see the Arduino Integer

Constants (http://adafru.it/deR)page.

Reading GPIO Pins

Reading is a little trickier: You need to separate the individual pin values from the byte that is

returned from the read(). A read can return one of 5 values:

0x0 (B00000000) - Both pins LOW

0x1 (B00000001) - IOA = HIGH, IOB = LOW

0x2 (B00000010) - IOA = LOW, IOB = HIGH

0x3 (B00000011) - Both pins HIGH

0xFF (B11111111) - Read Failed!

To extract the state of an individual pin, you will need to use a little binary

math (http://adafru.it/deS). In particular the "bitwise AND" operator: "&".

If you AND the read value from the GPIO breakout with the bit pattern of the pin you are

interested in, you will get a boolean "TRUE" if the pin is HIGH and a "FALSE" if the pin is LOW.

The following code snippet prints "A" if IOA is HIGH and "B" if IOB is HIGH.

/* Write */

bool ok = false;

ok = write(B00000001);

if (!ok) Serial.println(F("Wire failed"));

delay(1000);

ok = write(B00000010);

if (!ok) Serial.println(F("Wire failed"));

delay(1000);

uint8_t state = read();

const int IOA = 0x1;

const int IOB = 0x2;

if (state == -1)

{

Serial.println(F("Failed reading the DS2413"));

}

else

{

if (state & IOA)

{

Serial.println("A");

}

if (state & IOB)

{

Serial.println("B");

}