#ifndef PORTIOE_H
#define PORTIOE_H
#include <inttypes.h>

/* The pins of an IC's port can be split between PortWrite, PortRead, and LED.

PortIOE contains outputVal, the value of a port's output register.
outputVal is used for port manipulation by classes PortWrite and LED.
One port's outputVal can be shared by strobe pins and multiple LED pins.

PortIOE is only used by I/O expander port classes.
AVR port classes do not need a similar class because PORTx is global in the Arduino library.

Instantiation
 ------------
Example PortIOE::DEVICE_ADDR initilization:
    const uint8_t PortIOE::DEVICE_ADDR = 0x18;
Be careful with the DEVICE_ADDR.
Table 6 in PCA9655E datasheet lists 8-bit versions of I2C addresses.
The Arduino Wire library uses 7-bit addresses throughout, so drop the low bit.
For example, I2C address with AD2=GND AD1=SCL AD0=SCL,
    Table 6 lists      8-bit DEVICE_ADDR = 0x30 (b 00110000)
    while Arduino uses 7-bit DEVICE_ADDR = 0x18 (b 00011000)
http://playground.arduino.cc/Main/WireLibraryDetailedReference
The PCA9655E data sheet is on http://www.onsemi.com/pub_link/Collateral/PCA9655E-D.PDF

portNumber: If the I/O expander uses port letters, use 0 inplace of A, use 1 inplace of B.
*/
struct PortIOE
{
    static const uint8_t DEVICE_ADDR;
    const uint8_t num;                          //port identification number
    uint8_t outputVal;                          //bit value of output register for LEDs

    PortIOE(const uint8_t portNumber)
        : num(portNumber), outputVal(0) {}
};
#endif