Timers; 8-Bit Timers - Toshiba TLCS-90 Series Data Book

TOSHIBA
TMP90C840
3.6 Timers
The TMP90C840 incorporates four 8-bit timers and a 16-bit multi-function
timer/event counter.
The four 8-bit timers can operate independently,
two 16-bit timers through cascade connection.
operating modes are provided for the 8-bit timers:
o
8~bit
interval timer mode (4 timers)
o l6-bit interval timer mode (2 timers)
and also function as
The following four
possible arrangements: 8-bit x 2 and 16-bit x 1, or 16-bit x 2
o 8-bit programmable square wave (pulse) generation (pPG) mode (2
timers)
o 8-bit pulse width modulation (PWM) mode (2 timers)
The 16-bit multi-function timer/event counter can operate 1n the
following six modes:
a 16-bit interval timer mode
o l6-bit event counter mode
o 16-bit programmable square wave (pulse) generation (pPG) mode
o Frequency measurement mode
a Pulse width measurement mode
o Timer deviation measurement mode
3.6.1 8-bit timers
The TMP90C840 incorporates four 8-bit interval timers (Timers 0, 1, 2
and 3), each of which can be operated independently. The cascade
connection of Timer 0 and 1, or Timer 2 and 3 allows these timers used
as 16-bit internal timers.
Fig. 3.6 (1) is a block diagram of the 8-bit timers (Timer 0 and Timer
O.
Timer 2 and 3 have the same circuit configuration as Timer 0 and Timer
1 respectively.
Each interval timer
comparator and an
(TFF1/TFF3) provided
and Timer 3.
is composed of an 8-bit up-counter, an 8-bit
8-bit timer/register, with a Timer Flip-flop
to each pair of Timer 0 and Timer 1 and Timer 2
Internal clocks
(~T1, ~T16
and
~T256),
some of the input clock sources
for the interval timers, are generated by the 9-bit prescaler shown in
Fig. 3.6 (2).
Their operating modes of the 8-bit timers and flip-flops are
controlled by four control registers (TCLK, TFFCR, TMOD and TRUN).
MPU90-73