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Preliminary User’s Manual S14767EJ1V0UM00
457
CHAPTER 8 TIMER
8.1 Overview
There are two Timers. The timers are clocked at the system clock rate. All two timers are read/writable by the CPU.
Timers can be read by the CPU while they are counting. They can be automatically reloaded with the previously
loaded value and restarted or can be stopped while in progress. Two timers issues interrupt to the CPU upon reaching
their maximum value, the interrupts can be enabled/disabled.
The TM0IS and TM1IS fields in the Interrupt Status Register “S_ISR” indicate the end of timer count, when set
indicate there is a timer event that completed. All timers count up. The read-write registers “TM0CSR” or “TM1CSR”
have different offset from the read register so write registers are not affected while a value is read from the read
registers “TM0CCR” / ”TM1CCR” which indicate a running count of the timer/counter at a given time. Once a value is
loaded in the TM0CSR/TM1CSR, it stays there until Timer’s interrupts are cleared in the Interrupt Status Register
“S_ISR”. The original value can be reloaded in the counter to restart it from that count if Timer CH0 / CH1 reload
enable bit is set in the Timer Mode Register “TMMR”. Interrupts are automatically cleared upon CPU reading the
Interrupt Status Register of System Controller “S_ISR”.
8.2 Block Diagram
to S_ISR
TM0CSR
TM1CSR
TM0CCR
TM1CCR
CH0 DOWN COUNTER
TMMR
CH0 DOWN COUNTER
to S_ISR
to CPU
from CPU
from CPU
to CPU
from CPU
to CPU
CPU clock
100MHz/66MHz