Texas Instruments TMS320C3x - Manual (Page 389)

Timers
12-10
12.1.6 Timer Operation Modes
The timer can receive its input and send its output in several different modes,
depending upon the setting of CLKSRC, FUNC, and I/O. The four timer modes
of operation are defined in the following sections.
12.1.6.1 CLKSRC = 1 and FUNC = 0
If CLKSRC = 1 and FUNC = 0, the timer input comes from the internal clock.
The internal clock is not affected by the INV bit in the global-control register.
In this mode, TCLK is connected to the I/O port control, and you use TCLK as
a general-purpose I/O pin (see Figure 12–5).
- If I/O = 0, TCLK is configured as a general-purpose input pin whose state
you can read in DATIN. DATOUT has no effect on TCLK or DATIN. See
Figure 12–5 (a).
- If I/O = 1, TCLK is configured as a general-purpose output pin. DATOUT
is placed on TCLK and can be read in DATIN. See Figure 12–5 (b).
Figure 12–5. Timer Configuration with CLKSRC = 1 and FUNC = 0
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CLKSRC=1 (internal)
FUNC=0 (I/O pin)
I/O=0 (input)
I/O port
control
TCLK
External Internal
Output
DATIN
Input
Internal
clock
TSTAT
Timer
DATIN
DATOUT
Internal External
TCLK
control
I/O port
Timer
TSTAT
clock
Internal
Output
Input
(a) (b) CLKSRC = 1 (internal)
FUNC = 0 (I/O pin)
I/O = 1 (output)