COP880C Datasheet, PDF (16/31 Pages) National Semiconductor (TI) – Microcontrollers

Functional Description (Continued)
CNTRL
Bits
765
000
001
010
011
100
101
110
111
FIGURE 8. MICROWIRE/PLUS Application
TABLE 5. Timer Operating Modes
Operation Mode
External Counter W/Auto-Load Reg.
External Counter W/Auto-Load Reg.
Not Allowed
Not Allowed
Timer W/Auto-Load Reg.
Timer W/Auto-Load Reg./Toggle TIO Out
Timer W/Capture Register
Timer W/Capture Register
T Interrupt
Timer Underflow
Timer Underflow
Not Allowed
Not Allowed
Timer Underflow
Timer Underflow
TIO Pos. Edge
TIO Neg. Edge
DS010802-10
Timer
Counts
On
TIO Pos. Edge
TIO Neg. Edge
Not Allowed
Not Allowed
t_C
t_C
t_C
t_C
DS010802-11
FIGURE 9. Timer/Counter Auto
Reload Mode Block Diagram
DS010802-12
FIGURE 10. Timer Capture Mode Block Diagram
TIMER PWM APPLICATION
Figure 11 shows how a minimal component D/A converter
can be built out of the Timer-Register pair in the Auto-Reload
mode. The timer is placed in the “Timer with auto reload”
mode and the TIO pin is selected as the timer output. At the
outset the TIO pin is set high, the timer T1 holds the on time
and the register R1 holds the signal off time. Setting TRUN
bit starts the timer which counts down at the instruction cycle
rate. The underflow toggles the TIO output and copies the off
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