Inverter (Inv) Bit Operation - Motorola DSP56303 User Manual

Triple Timer Module Programming Model
Table 9-3. Timer Control/Status Register (TCSR) Bit Definitions (Continued)
Bit Number Bit Name
2 TCIE
1 TOIE
0 TE
TIO Programmed as Input
Mode
INV = 0
0 GPIO signal on the TIO
signal read directly.
1 Counter is incremented on
the rising edge of the signal
from the TIO signal.
2 Counter is incremented on
the rising edge of the signal
from the TIO signal.
3 Counter is incremented on
the rising edge of the signal
from the TIO signal.
9-32
Reset Value
0 Timer Compare Interrupt Enable
Enables/disables the timer compare interrupts. When set, TCIE enables
the compare interrupts. In the timer, pulse width modulation (PWM), or
watchdog modes, a compare interrupt is generated after the counter value
matches the value of the TCPR. The counter starts counting up from the
number loaded from the TLR and if the TCPR value is M, an interrupt
occurs after (M – N + 1) events, where N is the value of TLR. When
cleared, the TCSR[TCIE] bit disables the compare interrupts.
0 Timer Overflow Interrupt Enable
Enables timer overflow interrupts. When set, TOIE enables overflow
interrupt generation. The timer counter can hold a maximum value of
$FFFFFF. When the counter value is at the maximum value and a new
event causes the counter to be incremented to $000000, the timer
generates an overflow interrupt. When cleared, the TOIE bit disables
overflow interrupt generation.
0 Timer Enable
Enables/disables the timer. When set, TE enables the timer and clears the
timer counter. The counter starts counting according to the mode selected
by the timer control (TC[3–0]) bit values. When clear, TE bit disables the
timer.
NOTE: When all three timers are disabled and the signals are not in GPIO
mode, all three TIO signals are tri-stated. To prevent undesired spikes on
the TIO signals when you switch from tri-state into active state, these
signals should be tied to the high or low signal state by pull-up or pull-down
resistors.
Table 9-4. Inverter (INV) Bit Operation
INV = 1
GPIO signal on the TIO
signal inverted.
Counter is incremented on
the falling edge of the
signal from the TIO signal.
Counter is incremented on
the falling edge of the
signal from the TIO signal.
Counter is incremented on
the falling edge of the
signal from the TIO signal.
DSP56303 User's Manual
Description
TIO Programmed as Output
INV = 0
Bit written to GPIO Bit written to GPIO
put on TIO signal inverted and put on
directly. TIO signal.
—
Initial output put on Initial output inverted
TIO signal directly. and put on TIO signal.
—
INV = 1
—
—