Function; Timer Mode - Philips CEM2100/00 Service Manual

9.3 Function

The timer/counter 2 has three operating modes: timer, event counter and window modes.
And if fc or fs is selected as the source clock in timer mode, when switching the timer mode from SLOW1 to
NORMAL2, the timer/counter2 can generate warm-up time until the oscillator is stable.

9.3.1 Timer mode

In this mode, the internal clock is used for counting up. The contents of TC2DR are compared with the con-
tents of up counter. If a match is found, a timer/counter 2 interrupt (INTTC2) is generated, and the counter is
cleared. Counting up is resumed after the counter is cleared.
When fc is selected for source clock at SLOW2 mode, lower 11-bits of TC2DR are ignored and generated a
interrupt by matching upper 5-bits only. Though, in this situation, it is necessary to set TC2DRH only.
Table 9-1 Source Clock (Internal clock) for Timer/Counter2 (at fc = 16 MHz, DV7CK=0)
TC2C
K
DV7CK = 0
Resolution
000 524.29 [ms]
001 512.0 [ms]
010 16.0 [ms]
011 0.5 [ms]
100 –
101 30.52 [ms]
Note:When fc is selected as the source clock in timer mode, it is used at warm-up for switching from SLOW1 mode
to NORMAL2 mode.
Example :Sets the timer mode with source clock fc/2
NORMAL1/2, IDLE1/2 mode
Maximum Time Set-
Resolution
ting
9.54 [h] 1 [s]
33.55 [s] 0.98 [ms]
1.05 [s] 16.0 [ms]
32.77 [ms] 0.5 [ms]
– –
2 [s] 30.52 [ms]
3
[Hz] and generates an interrupt every 25 ms (at fc = 16 MHz )
LDW (TC2DR), 061AH
DI
SET (EIRE). 6
EI
LD (TC2CR), 00001000B
LD (TC2CR), 00101000B
Page 95
SLOW1/2 mode
DV7CK = 1
Maximum Time Set- Resolu-
ting tion
18.2 [h] 1 [s]
1.07 [min] 0.98 [ms]
1.05 [s] –
32.77 [ms] –
– 62.5 [ns]
2 [s] –
8
; Sets TC2DR (25 ms ³ 2 /fc = 061AH)
; IMF= "0"
; Enables INTTC2 interrupt
; IMF= "1"
; Source clock / mode select
; Starts Timer
T5CL8
SLEEP1/2 mode
Maxi- Maxi-
mum Resolu- mum
Time tion Time
Setting Setting
18.2 [h] 1 [s] 18.2 [h]
1.07 1.07
0.98 [ms]
[min] [min]
– – –
– – –
– – –
– – –