Rev. 1.0, 02/00, page 286 of 1141
14.3
Operation
Timer L is an 8-bit up/down counter.
The inputting clock for Timer L can be selected by the LMR2 to LMR0 bits of the LMR from the
choices of the internal clock (
φ
/128 and
φ
/64), DVCDG2, PB and REC-CTL.
Timer L is provided with three different types of operation modes, namely, the compare match
clear mode when controlled to the up-counting function, the auto reloading mode when controlled
to the down-counting function and the interval timer mode.
Respective operation modes and operation methods will be explained below.
14.3.1
Compare Match Clear Operation
When the LMR3 bit of the LMR is cleared to 0, timer L will be controlled to the up-counting
function.
When any other values than H'00 are written into the RCR, the LTC will be cleared to H'00
simultaneously before starting counting up.
Figure 14.2 shows RCR writing and LTC clearing timing. When the LTC value and the RCR
value match (compare match), the LTC readings will be cleared to H'00 to resume counting from
H'00.
Figure 14.3 indicated on the next page shows the compare match clear timing.
RCR
LTC
φ
Write signal
1 state
N
H' 00
Figure 14.2 RCR Writing and LTC Clearing Timing Chart