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===== AVR32 UC3A controlling GPIO =====

For the UC3A0512, read the pin value register and then write to the output value register.

// Set the output value of PORT0 \\
     AVR32_GPIO.port[ 0 ].ovrs = value ; \\

//Clear the output value of PORT0 \\
     AVR32_GPIO.port[ 0 ].ovrc = value ;\\

//Read the port pins \\
     value = AVR32_GPIO.port[ 0 ].pvr ; \\

You can also use the .ovr function:\\

Example PORT0 has the value 0xAAFF55FF\\

AVR32_GPOI.port[0].ovr = 0x55AAFFBB;\\

then all the bits will change, because if you use the ovrs or ovrc you can only change set or clear. \\

Look at the user manual page 44 you will find the PORTA, PORTB, PORTC and PORTX to GPIO mapping.

These GPIOs are divided in 32 bit ports or registers. This division is called as PORT0, PORT1, and so forth. While selecting any pin functionality, one has to modify the PORT0, PORT1, etc registers.
The registers related to these ports are GPER, PMR0, PMR1 etc.

To select a particular pin as gpio, for example PORTB.0. Goto to page 44, the GPIO mapping is 32. Hence, it is PORT1.0. So, set the LSB of PORT1 GPER register.

On page 174 you will find the PORT0, PORT1, etc offsets from the base address. Section 22.5 from the user manual explains it all.

If you want to set one or even more bits at a port you can use
     OVRS = (Bit(x) | Bit(y));
with
     #define Bit(i) (1 << (i)).
If you want to clear some bits just use
     OVRC = Bit(z);
If you just want to toggle one or more bits use
OVRT = Bit(x); and this bit has the inverted level without influencing the others during that operation.
If you want to set some bits to a specific value like for your display port you can also use toggle instead of clearing all and setting the used once like
OVRT = (OVR & AllBitMask) ^ (NewValue << Offset);
Here you used the read function as well as the toggle function and set all bits simultaneously. Independent of there level.

The GPER(S/C/T) is used logically the some way to use a port pin as a port pin or not. If you clear it the port pin is connected to one of the internal modules like USART, TWI, SPI or Timer. You have to set GPER to use a port pin as a port pin. But don't forget to set the output driver too. Otherwise you have a port pin but you output value is not driven.
If you want a pure output you should also clear the ODMER otherwise you have an open drain driver if the device is populated with it.\\
And last but not least you should also clear the PUER to keep your power consumption low.

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