UPD784026 Renesas Electronics Corporation., UPD784026 Datasheet - Page 396

• Manufacturer Part Number: UPD784026
• Description: 16/8-bit Single-chip Microcontrollers
• Manufacturer: Renesas Electronics Corporation.

11.7 CAUTIONS
(1) There is a possibility of misoperation if the next register contents are rewritten while the timer 3 is running (when the
(2) If the compare register (CR30) and TM3 contents match when an instruction that stops timer register 3 (TM3) operation
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CE3 bit of the timer control register 0 (TMC0) is set). The misoperation occurs as there is no defined order of priority
in the event of contention between the timings at which the hardware function changes due to a register rewrite and
the status changes in the function prior to the rewrite.
When the contents of following registers are rewritten, counter operations must be stopped first to ensure stability.
• Prescaler mode register 0 (PRM0)
is executed, the TM3 count operation stops, but an interrupt request is generated.
If you do not want an interrupt to be generated when TM3 operation is stopped, interrupts should be masked by means
of interrupt the mask register before stopping the TM3.
Example
Program in which an interrupt request may be
generated
CLR1 CE3
SET1 CMK30
Interrupt request generated
by timer 3 here
CHAPTER 11 TIMER 3
Program in which an interrupt request is not generated
SET1 CMK30
CLR1 CE3
CLR1 CIF30
Disables interrupts from timer 3
Clears timer 3 interrupt request flag