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CHAPTER 14 16-BIT RELOAD TIMER
14.4 Interrupts of 16-bit Reload Timer
The 16-bit reload timer generates an interrupt request when the 16-bit timer register
(TMR) underflows.
■ Interrupts of 16-bit Reload Timer
When the value of the TMR is decremented from "0000
H
" to "FFFF
H
" during the TMR count operation, an
underflow occurs. When an underflow occurs, the underflow generating flag bit in the timer control status
register (TMCSR:UF) is set to l. When an underflow interrupt is enabled (TMCSR:INTE = 1), an interrupt
request is generated.
■ Correspondence between 16-bit Reload Timer Interrupt and EI
2
OS
■ EI
2
OS Function of 16-bit Reload Timer
The 16-bit reload timers 2 and 3 correspond to the EI
2
OS function. An underflow in the TMR starts the
EI
2
OS.
However, the EI
2
OS is available only when other resources sharing the interrupt control register (ICR) do
not use interrupts. The 16-bit reload timers 2 and 3 share the ICR04. When using the EI
2
OS in the 16-bit
reload timers 2 and 3, it is necessary to disable the interrupt of the 16-bit reload timer sharing the interrupt
control register.
Table 14.4-1 Interrupt Control Bits and Interrupt Factors of 16-bit Reload Timer
16-bit Reload Timer 2 16-bit Reload Timer 3
Interrupt request flag bit TMCSR2: UF TMCSR3: UF
Interrupt request enable bit TMCSR2: INTE TMCSR3: INTE
Interrupt factor Underflow in TMR2 Underflow in TMR3
Reference: For details of the interrupt number, interrupt control register, and interrupt vector address, see "CHAPTER
3 INTERRUPTS".