HD404369F datasheet(56/117 Pages) RENESAS

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HD404369 Series

Timers

The MCU has four timer/counters (A to C).

• Timer A: Free-running timer

• Timer B: Multifunction timer

• Timer C: Multifunction timer

Timer A is an 8-bit free-running timer. Timers B and C are 8-bit multifunction timers, whose functions are

listed in table 25. The operating modes are selected by software.

Timer A

Timer A Functions: Timer A has the following functions.

• Free-running timer

• Clock time-base

The block diagram of timer A is shown in figure 36.

Timer A Operations:

• Free-running timer operation: The input clock for timer A is selected by timer mode register A (TMA:

$008).

Timer A is reset to $00 by MCU reset and incremented at each input clock. If an input clock is applied

to timer A after it has reached $FF, an overflow is generated, and timer A is reset to $00. The overflow

sets the timer A interrupt request flag (IFTA: $001, bit 2). Timer A continues to be incremented after

reset to $00, and therefore it generates regular interrupts every 256 clocks.

• Clock time-base operation: Timer A is used as a clock time-base by setting bit 3 (TMA3) of timer mode

interrupts at the correct timing based on the 32.768-kHz crystal oscillation. In this case, prescaler W and

timer A can be reset to $00 by software.

Registers for Timer A Operation: Timer A operating modes are set by the following registers.

• Timer mode register A (TMA: $008): Four-bit write-only register that selects timer A’s operating mode

and input clock source as shown in figure 37.

HD404369F Scheda tecnica(PDF) 56 Page - Renesas Technology Corp