TIMER/EVENT COUNTER MODES OF OPERATION
MOTOROLA
DSP56002 TIMER AND EVENT COUNTER
7 - 11
by two (CLK/2). The counter is loaded with 0 by the first transition occurring on the TIO
input pin and starts incrementing. When the first edge of opposite polarity occurs on TIO,
the counter stops, the TS bit in TCSR is set and, if TIE is set, an interrupt is generated.
The contents of the counter is loaded into the TCR. The user’s program can read the TCR,
which now represents the widths of the TIO pulse. The process is repeated until the timer
is disabled (TE=0).The INV bit determines whether the counting is enabled when TIO is
high (INV=0) or when TIO is low (INV=1). Figure 7-8 illustrates Timer Mode 4 when INV=0
and Figure 7-9 illustrates Timer Mode 4 with INV=1.
TE
TCR
Write Preload (N)
N
Counter
N
0
N
Interrupt
First Event
Last Event
N-1
TIO
New Event
2xCLK
N-1
Clock (CLK/2)
Figure 7-6 Standard Timer Mode, Internal Clock, Output Pulse Enabled (INV=1)
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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Содержание DSP56002
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