TMP86C420FG Datasheet, PDF (72/160 Pages) Toshiba Semiconductor – 8 Bit Microcontroller

6. Time Base Timer (TBT)
6.1 Time Base Timer
TMP86C420FG
Note 2: The interrupt frequency (TBTCK) must be selected with the time base timer disabled (TBTEN="0"). (The interrupt fre-
quency must not be changed with the disable from the enable state.) Both frequency selection and enabling can be per-
formed simultaneously.
Example :Set the time base timer frequency to fc/2¹⁶ [Hz] and enable an INTTBT interrupt.
LD
(TBTCR) , 00000010B
; TBTCK ← 010
LD
(TBTCR) , 00001010B
; TBTEN ← 1
DI
; IMF ← 0
SET
(EIRL) . 6
Table 6-1 Time Base Timer Interrupt Frequency ( Example : fc = 16.0 MHz, fs = 32.768 kHz )
TBTCK
000
001
010
011
100
101
110
111
Time Base Timer Interrupt Frequency [Hz]
NORMAL1/2, IDLE1/2 Mode NORMAL1/2, IDLE1/2 Mode SLOW1/2, SLEEP1/2 Mode
DV7CK = 0
DV7CK = 1
1.91
1
1
7.63
4
4
244.14
128
–
976.56
512
–
1953.13
1024
–
3906.25
2048
–
7812.5
4096
–
31250
16384
–
6.1.3 Function
An INTTBT ( Time Base Timer Interrupt ) is generated on the first falling edge of source clock ( The divider
output of the timing generator which is selected by TBTCK. ) after time base timer has been enabled.
The divider is not cleared by the program; therefore, only the first interrupt may be generated ahead of the set
interrupt period ( Figure 6-2 ).
Source clock
TBTCR<TBTEN>
INTTBT
Enable TBT
Interrupt period
Figure 6-2 Time Base Timer Interrupt
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