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CHAPTER 24: 16-BIT FREE-RUN TIMER
5. Operation
FUJITSU SEMICONDUCTOR LIMITED
CHAPTER : 16-BIT FREE-RUN TIMER
FUJITSU SEMICONDUCTOR CONFIDENTIAL
48
5.4. Notes on Operating Specifications
Notes on operating specifications are explained.
5.4.1.
Notes at Accessing the Buffer Registers
The CPCLR register in the free-run timer has a buffer function. Do not use a read-modify-write instruction
when accessing this register.
5.4.2.
Notes on Using the 16-bit Free-run Timer
Notes on setting by a program
⋅
When you execute reset, the timer value becomes "0000
H
", however, the 0 detection interrupt flag will
not be configured.
⋅
Since the timer mode bit (MODE of the TCCS register) has a buffer, the timer mode changed after the
0 detection becomes valid.
⋅
Software clear (SCLR of the TCCS register is 1) initializes the timer, but it does not generate the 0
detection interrupt.
⋅
When you start counting while the compare value and count value match, the compare clear flag will
not be configured.
⋅
Set the value other than "0000
H
" for the compare value. When setting the value, consider that the
following operation will happen.
- When the timer mode bit (MODE in TCCS register) is in the up count mode, the timer value is
updated to "0000
H
" and then is fixed to "0000
H
". The 0 detection interrupt flag and the compare
clear flag continue to be set every count clock.
- When the timer mode bit (MODE in TCCS register) is in the up down count mode, the timer value
repeats the up count operation from "0000
H
" to "FFFF
H
". The 0 detection interrupt flag and the
compare clear flag are set when the timer value and "0000
H
" match.
Notes on interrupts
⋅
Always clear the interrupt flag (IRQZF) before setting the interrupt request enable bit (IRQZE) of the
timer state control register (TCCS) to 1.
⋅
Always clear the interrupt flag (ICLR) before setting the interrupt request enable bit (ICRE) of the
timer state control register (TCCS) to 1.
Notes on accessing the TCCS register
⋅
For the read-modify-write instruction, setting value will be read out from the MSI2 to MSI0/MSI5 to
MSI3.
⋅
For the normal reading mode, the counter value will be read out from the MSI2 to MSI0/MSI5 to
MSI3.
MB91520 Series
MN705-00010-1v0-E
955