Texas Instruments TMS320C645X - Manual (Page 12)

GPIO Function
General-Purpose Input/Output (GPIO) 12 SPRU724
2 GPIO Function
You can independently configure each GPIO pin (GPn) as either an input or
an output using the GPIO direction registers. The GPIO direction register
(DIR) specifies the direction of each GPIO signal. Logic 0 indicates the GPIO
pin is configured as output, and logic 1 indicates input.
When configured as output, writing a 1 to a bit in the set data register drives
the corresponding GPn to a logic-high state. Writing a 1 to a bit in the clear data
register drives the corresponding GPn to a logic-low state. The output state of
each GPn can also be directly controlled by writing to the output data register.
For example, to set GP8 to a logic-high state, the software can perform one
of the following:
- Write 0x100 to the SET_DATA register
- Read in OUT_DATA register, change the eighth bit to 1, and write the new
value back to OUT_DATA
To set GP8 to a logic-low state, the software can perform one of the following:
- Write 0x100 to the CLR_DATA register
- Read in OUT_DATA register, change the eighth bit to 0, and write the new
value back to OUT_DATA
Note that writing a 0 to bits in the set data and clear data registers does not
affect the GPIO pin state. Also, for GPIO pins configured as input, writing to
the set data, clear data, or output data registers does not affect the pin state.
For a GPIO pin configured as input, reading the input data register (IN_DATA)
will return the pin state.
Reading the SET_DATA register or the CLR_DATA data register will return the
value in OUT_DATA, not the actual pin state. The pin state is available by
reading the input data register.