Motorola DragonBall MC68328 User Manual page 111

UART
GPIO DELTA
This bit indicates that a change occurred on the GPIO pin. If the GPIO interrupt is enabled,
this bit posts an interrupt. Users can write this bit to a 1, posting an immediate interrupt
for debugging purposes. This bit must be cleared by writing 0 to clear the GPIO interrupt.
0 = no GPIO interrupt posted
1 = GPIO interrupt posted
GPIO
This bit contains the current status of the GPIO pin. If GPIO is configured as an input,
users can read this bit. If GPIO is configured as an output, this bit controls the pin.
0 = GPIO pin is low
1 = GPIO pin is high
GPIO DIR
This bit controls the direction of the GPIO pin. While this bit is high, the pin is an input.
While this bit is low, GPIO is an output.
0 = GPIO is input
1 = GPIO is output
GPIO SRC
This bit controls the source of the GPIO pin. While high, the source is the 1x clock from
the baud-rate generator. While low, the source is the GPIO bit. While the GPIO DIR bit is
0, this bit has no function.
0 = GPIO driven by GPIO bit
1 = GPIO driven by bit clock from baud generator
BAUD SRC
This bit controls the clock source to the baud-rate generator.
0 = Baud generator source is system clock
1 = Baud generator source is GPIO pin (GPIO Dir must be 0)
DIVIDER
These bits control the clock frequency produced by the baud generator. The bits are en-
coded as follows:
000 = divide by 1
001 = divide by 2
010 = divide by 4
011 = divide by 8
100 = divide by 16
101 = divide by 32
110 = divide by 64
111 = divide by 128
8-8 MC68328 DRAGONBALL PROCESSOR USER'S MANUAL MOTOROLA