Motorola DSP96002 - Manual (Page 810)

28 MOTOROLA
6 INTRODUCTION TO THE TIMER/EVENT COUNTER
This section describes the two identical and independent timer/event counter modules
now featured on the DSP96002. The timer can use internal or external clocking and can
interrupt the processor after a number of events specified by a user program, or it can sig-
nal an external device after counting internal events. The timer can also be used to trigger
DMA transfers after a specified number of events (clocks) occurs.
Each timer connects to the external world through its own bidirectional TIO pin. When TIO
is used as input, the module is functioning as an external event counter or is measuring
external pulse width/signal period. When TIO is used as output, the module is functioning
as a timer and TIO becomes the timer pulse. When the TIO pin is not used by the timer
module it can be used as a general purpose I/O (GPIO) pin.
Note: When the timer is disabled, the TIO pin becomes three-stated. To prevent undes-
ired spikes from occurring, the TIO pin should be pulled up or down when it is not in use.
6.1 TIMER BLOCK DIAGRAM
Figure 5 shows a block diagram of the timer module. It includes a 32-bit read-write Timer
Control and Status Register (TCSR), a 32-bit read-write Timer Count Register (TCR), a
32-bit counter, and logic for clock selection and interrupt generation.
Figure 5 - Single Timer Module Block Diagram
Register addresses are shown in Figure 5 on page 28.
GDB
Timer Control/Status Register (TCSR)
Interrupt
C
o
u
n
t
e
r
T
C
R
INV bit TE bit
TC2-TC0
TIO
CLK/2
0
1
DIR
3
24
24 24
111
32
TIE bit