Warm-Up Counter Mode; Low-Frequency Warm-Up Counter Mode - Philips CEM2100/00 Service Manual

11.3.9 Warm-Up Counter Mode

In this mode, the warm-up period time is obtained to assure oscillation stability when the system clocking is
switched between the high-frequency and low-frequency. The timer counter 5 and 6 are cascadable to form a
16-bit TimerCounter. The warm-up counter mode has two types of mode; switching from the high-frequency to
low-frequency, and vice-versa.
Note 1: In the warm-up counter mode, fix TCiCR<TFFi> to 0. If not fixed, the
pulses.
Note 2: In the warm-up counter mode, only upper 8 bits of the timer register TTREG6 and 5 are used for match
detection and lower 8 bits are not used.
Note 3: i = 5, 6

11.3.9.1 Low-Frequency Warm-up Counter Mode

(NORMAL1 → NORMAL2 → SLOW2 → SLOW1)
In this mode, the warm-up period time from a stop of the low-frequency clock fs to oscillation stability
is obtained. Before starting the timer, set SYSCR2<XTEN> to 1 to oscillate the low-frequency clock.
When a match between the up-counter and the timer register (TTREG6, 5) value is detected after the timer
is started by setting TC6CR<TC6S> to 1, the counter is cleared by generating the INTTC6 interrupt
request. After stopping the timer in the INTTC6 interrupt service routine, set SYSCR2<SYSCK> to 1 to
switch the system clock from the high-frequency to low-frequency, and then clear of SYSCR2<XEN> to
0 to stop the high-frequency clock.
Table 11-8 Setting Time of Low-Frequency Warm-Up Counter Mode (fs = 32.768 kHz)
Example :After checking low-frequency clock oscillation stability with TC6 and 5, switching to the SLOW1 mode
PINTTC6:
VINTTC6:
Minimum Time Setting
(TTREG6, 5 = 0100H)
7.81 ms
SET (SYSCR2).6
LD (TC5CR), 43H
LD (TC6CR), 05H
LD (TTREG5), 8000H
DI
SET (EIRE). 2
EI
SET (TC6CR).3
: :
CLR (TC6CR).3
SET (SYSCR2).5
CLR (SYSCR2).7
RETI
: :
DW PINTTC6
Page 137
,
PDOi PWMi
Maximum Time Setting
(TTREG6, 5 = FF00H)
1.99 s
←
: SYSCR2<XTEN> 1
: Sets TFF5=0, source clock fs, and 16-bit mode.
: Sets TFF6=0, and warm-up counter mode.
: Sets the warm-up time.
(The warm-up time depends on the oscillator characteristic.)
←
: IMF 0
: Enables the INTTC6.
←
: IMF 1
: Starts TC6 and 5.
: Stops TC6 and 5.
←
: SYSCR2<SYSCK> 1
(Switches the system clock to the low-frequency clock.)
←
: SYSCR2<XEN> 0 (Stops the high-frequency clock.)
: INTTC6 vector table
T5CL8
and pins may output
PPGi