tsc693e ETC-unknow, tsc693e Datasheet - Page 36

• Manufacturer Part Number: tsc693e
• Description: Memory Controller
• Manufacturer: ETC-unknow

3.13. General Purpose and Real Time Clock Timers
Two timers (apart from the special Watchdog timer) are available in the MEC. These
timers provide, in addition to a generalized counter mechanisms, a mechanism for
setting the step size in which actual time counts are performed (a two-stage counter).
Each timer/counter pulse generator consists of two parts:
-
-
SCALER is a counter to adjust the step size in which COUNTER does the actual time
count.
COUNTER is a counter to actually count time in steps as set by the value in SCALER.
COUNTER is decrements when SCALER reaches zero.
The implementation is shown in Figure 6.
Figure 6 - Timer implementation
Both timers are clocked by the internal system clock. The timers are programmable by
writing to the Timer Control Register (see page 59). They are possible to program to
be either of single-shot type or periodical type, in both cases generate an interrupt when
the delay time has elapsed. If the timer is not programmed with a new value when set to
periodical type, it restarts from the latest programmed value and continue to count
down, thus generating interrupts periodically. The Real Time Clock Timer interrupt
has higher priority than the General Purpose Timer interrupt. It is possible to halt and
restart the timers by writing to the Timer Control Register. The only functional
difference between the two timers is that the Real Time Clock Timer has an 8-bit
scaler while the General Purpose Timer has a 16-bit scaler providing a wider range.
While the signal CPUHALT* is active, the timers are temporary halted.
MATRA MHS
Rev. D (10 Apr. 97)
SYSCLK
pre-SCALER
COUNTER
Control (Enable, Load, Reload, Hold, Stop at zero)
Set Preload
The Scaler
Timer function
Zero indication
Set Preload
The Counter
Interrupt
TSC693E
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