High-Frequency Warm-Up Counter Mode (Slow1 → Slow2 → Normal2 → Normal1) - Toshiba TLCS-870/C Series Manual

9. 8-Bit TimerCounter (TC3, TC4)
9.1 Configuration
9.3.9.2
bility is obtained. Before starting the timer, set SYSCR2<XEN> to 1 to oscillate the high-frequency clock.
When a match between the up-counter and the timer register (TTREG4, 3) value is detected after the timer
is started by setting TC4CR<TC4S> to 1, the counter is cleared by generating the INTTC4 interrupt
request. After stopping the timer in the INTTC4 interrupt service routine, clear SYSCR2<SYSCK> to 0 to
switch the system clock from the low-frequency to high-frequency, and then SYSCR2<XTEN> to 0 to
stop the low-frequency clock.
Table 9-9 Setting Time in High-Frequency Warm-Up Counter Mode
Example :After checking high-frequency clock oscillation stability with TC4 and 3, switching to the NORMAL1 mode
PINTTC4:
VINTTC4:
High-Frequency Warm-Up Counter Mode
(SLOW1 → SLOW2 → NORMAL2 → NORMAL1)
In this mode, the warm-up period time from a stop of the high-frequency clock fc to the oscillation sta-
Minimum time Setting
(TTREG4, 3 = 0100H)
16 µs
SET (SYSCR2).7
LD (TC3CR), 63H
LD (TC4CR), 05H
LD (TTREG3), 0F800H
DI
SET (EIRH). 3
EI
SET (TC4CR).3
: :
CLR (TC4CR).3
CLR (SYSCR2).5
CLR (SYSCR2).6
RETI
: :
DW PINTTC4
Maximum time Setting
(TTREG4, 3 = FF00H)
4.08 ms
←
: SYSCR2<XEN> 1
: Sets TFF3=0, source clock fc, and 16-bit mode.
: Sets TFF4=0, and warm-up counter mode.
: Sets the warm-up time.
(The warm-up time depends on the oscillator characteristic.)
←
: IMF 0
: Enables the INTTC4.
←
: IMF 1
: Starts the TC4 and 3.
: Stops the TC4 and 3.
←
: SYSCR2<SYSCK>
(Switches the system clock to the high-frequency clock.)
←
: SYSCR2<XTEN> 0
(Stops the low-frequency clock.)
: INTTC4 vector table
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