455A Group
TIMERS
• Fixed dividing frequency timer
The fixed dividing frequency timer has the fixed frequency
dividing ratio (n). An interrupt request flag is set to “1” after
every n count of a count pulse.
The 455A Group has the following timers.
• Programmable timer
The programmable timer has a reload register and enables the
frequency dividing ratio to be set. It is decremented from a
setting value n. When it underflows (count to n + 1), a timer
interrupt request flag is set to “1,” new data is loaded from the
reload register, and count continues (auto-reload function).
FF16
n : Counter initial value
Count starts
Reload
Reload
n
1st underflow
2nd underflow
0016
Time
n+1 count
n+1 count
“1”
“0”
Timer interrupt
request flag
An interrupt occurs or
a skip instruction is executed.
Fig 32. Auto-reload function
Rev.1.01 Feb 15, 2008 Page 30 of 146
REJ03B0224-0101
RENESAS [ RENESAS TECHNOLOGY CORP ]
