Toshiba – Toshiba TMP87CP24AF User Manual
Page 28
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TOSHIBA
TMP87CM24A/P24A
b. Switching from SLOW mode to NORMAL2 mode
First, set XEN (bit 7 in SYSCR2) to turn on the high-frequency oscillation. When time for
stabilization (warm-up) has been taken by the timer/counter 2 (TC2), clear SYSCK (bit 5 in
SYSCR2) to switch the main system clock to the high-frequency clock.
SLOW
mode
can
also
be
released
by
setting
the
RESET
pin
low,
which
immediately
performs
the
reset operation. After reset, the TMP87CM24A/P24A are placed in NORMAL mode.
Example : Switching from SLOW mode to NORMAL2 mode (fc =
8
MHz, warming-up time is about
7.9 ms).
SET
(SYSCR2). 7
; XEN<-1 (turns on high-frequency oscillation)
LD
(TC2CR), 10H
; Sets TC2 mode
(timer mode, source clock: fc)
LD
(TREG2+ 1), 0F8H
; Sets the warming-up time
(according to frequency and resonator characteristics)
SET
(EIRH). EF14
; Enable INTTC2
LD
(TC2CR), ЗОН
; Starts TC2
PINTTC2 :
LD
(TC2CR), ЮН
; Stops TC2
CLR
RETI
(SYSCR2). 5
; SYSCK<-0 (Switches the main system clock to the
high-frequency cicok)
VINTTC2:
DW
PINTTC2
; INTTC2 vector table
Note 1: After the SYSCK is cleared to "0", the CPU core operate using low frequency clock
when the main system clock is switching from low frequency clock to high frequency
clock.
Note 2: SLOW mode can also be released by setting the RESET pin low, which immediately
performs
the
reset
operation.
After
reset,
the
TMP87CM24A/P24A
are
placed
in
NORMAL2 mode. (The TMP87PP24A is placed in NORMAL1 mode)
3
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24-28
2002
-
10-03