参数资料
型号: M37272M6H-XXXSP
元件分类: 微控制器/微处理器
英文描述: 8-BIT, MROM, 8.1 MHz, MICROCONTROLLER, PDIP42
封装: 0.600 INCH, 1.78 MM PITCH, PLASTIC, SDIP-42
文件页数: 50/132页
文件大小: 1736K
代理商: M37272M6H-XXXSP
23
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER with CLOSED CAPTION DECODER
and ON-SCREEN DISPLAY CONTROLLER
M37272M6H/M8H/MAH/MFH–XXXSP/FP
M37272E8SP/FP, M37272EFSP/FP
MITSUBISHI MICROCOMPUTERS
Rev. 1.0
8.4 TIMERS
This microcomputer has 6 timers: timer 1, timer 2, timer 3, timer 4,
timer 5, and timer 6. All timers are 8-bit timers with the 8-bit timer
latch. The timer block diagram is shown in Figure 8.4.3.
All of the timers count down and their divide ratio is 1/(n+1), where n
is the value of timer latch. By writing a count value to the correspond-
ing timer latch (addresses 00F016 to 00F316 : timers 1 to 4, addresses
00EE16 and 00EF16 : timers 5 and 6), the value is also set to a timer,
simultaneously.
The count value is decremented by 1. The timer interrupt request bit
is set to “1” by a timer overflow at the next count pulse, after the
count value reaches “0016”.
8.4.1 Timer 1
Timer 1 can select one of the following count sources:
f(XIN)/16 or f(XCIN)/16
f(XIN)/4096 or f(XCIN)/4096
External clock from the TIM2 pin
The count source of timer 1 is selected by setting bits 5 and 0 of
timer mode register 1 (address 00F416). Either f(XIN) or f(XCIN) is
selected by bit 7 of the CPU mode register.
Timer 1 interrupt request occurs at timer 1 overflow.
8.4.2 Timer 2
Timer 2 can select one of the following count sources:
f(XIN)/16 or f(XCIN)/16
Timer 1 overflow signal
External clock from the TIM2 pin
The count source of timer 2 is selected by setting bits 4 and 1 of
timer mode register 1 (address 00F416). Either f(XIN) or f(XCIN) is
selected by bit 7 of the CPU mode register. When timer 1 overflow
signal is a count source for the timer 2, the timer 1 functions as an 8-
bit prescaler.
Timer 2 interrupt request occurs at timer 2 overflow.
8.4.3 Timer 3
Timer 3 can select one of the following count sources:
f(XIN)/16 or f(XCIN)/16
f(XCIN)
External clock from the TIM3 pin
The count source of timer 3 is selected by setting bit 0 of timer mode
register 2 (address 00F516) and bit 6 at address 00C716. Either f(XIN)
or f(XCIN) is selected by bit 7 of the CPU mode register.
Timer 3 interrupt request occurs at timer 3 overflow.
8.4.4 Timer 4
Timer 4 can select one of the following count sources:
f(XIN)/16 or f(XCIN)/16
f(XIN)/2 or f(XCIN)/2
f(XCIN)
The count source of timer 3 is selected by setting bits 1 and 4 of the
timer mode register 2 (address 00F516). Either f(XIN) or f(XCIN) is
selected by bit 7 of the CPU mode register. When timer 3 overflow
signal is a count source for the timer 4, the timer 3 functions as an 8-
bit prescaler.
Timer 4 interrupt request occurs at timer 4 overflow.
8.4.5 Timer 5
Timer 5 can select one of the following count sources:
f(XIN)/16 or f(XCIN)/16
Timer 2 overflow signal
Timer 4 overflow signal
The count source of timer 3 is selected by setting bit 6 of timer mode
register 1 (address 00F416) and bit 7 of the timer mode register 2
(address 00F516). When overflow of timer 2 or 4 is a count source
for timer 5, either timer 2 or 4 functions as an 8-bit prescaler. Either
f(XIN) or f(XCIN) is selected by bit 7 of the CPU mode register.
Timer 5 interrupt request occurs at timer 5 overflow.
8.4.6 Timer 6
Timer 6 can select one of the following count sources:
f(XIN)/16 or f(XCIN)/16
Timer 5 overflow signal
The count source of timer 6 is selected by setting bit 7 of the timer
mode register 1 (address 00F416). Either f(XIN) or f(XCIN) is selected
by bit 7 of the CPU mode register. When timer 5 overflow signal is a
count source for timer 6, the timer 5 functions as an 8-bit prescaler.
Timer 6 interrupt request occurs at timer 6 overflow.
At reset, timers 3 and 4 are connected by hardware and “FF16” is
automatically set in timer 3; “0716” in timer 4. The f(XIN) /16 is se-
lected as the timer 3 count source. The internal reset is released by
timer 4 overflow in this state and the internal clock is connected.
At execution of the STP instruction, timers 3 and 4 are connected by
hardware and “FF16” is automatically set in timer 3; “0716” in timer 4.
However, the f(XIN) /16 is not selected as the timer 3 count source.
So set both bit 0 of timer mode register 2 (address 00F516) and bit 6
at address 00C716 to “0” before the execution of the STP instruction
(f(XIN) /16 is selected as timer 3 count source). The internal STP
state is released by timer 4 overflow in this state and the internal
clock is connected.
As a result of the above procedure, the program can start under a
stable clock.
: When bit 7 of the CPU mode register (CM7) is “1,” f(XIN) becomes
f(XCIN).
The timer-related registers is shown in Figures 8.4.1 and 8.4.2.
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