HD4048412FS datasheet(68/127 Pages) RENESAS

68 / 127 page

HD404849 Series

Timer C Operations:

• Free-running/reload timer operation: The free-running/reload operation, input clock source, and

prescaler division ratio are selected by timer mode register C1 (TMC1: $00D).

Timer C is initialized to the value set in timer write register C (TWCL: $00E, TWCU: $00F) by

software and incremented by one at each clock input. If an input clock is applied to timer C after it has

reached $FF, an overflow is generated. In this case, if the reload timer function is enabled, timer C is

initialized to its initial value set in timer write register C; if the free-running timer function is enabled,

the timer is initialized to $00 and then incremented again.

The overflow sets the timer C interrupt request flag (IFTC: $002, bit 2). IFTC is reset by software or

MCU reset. Refer to figure 3 and table 1 for details.

• Watchdog timer operation: Timer C is used as a watchdog timer for detecting out-of-control program

routines by setting the watchdog on flag (WDON: $020, bit 1) to 1. If a program routine runs out of

control and an overflow is generated, the MCU is reset. Program runaway can be controlled by

initializing timer C by software before it reaches $FF.

• Timer output operation: The following four output modes can be selected for timer C by setting timer

mode register C2 (TMC2: $014).

 Toggle

 0 output

 1 output

 PWM output

By selecting the timer output mode, pin R1

1/TOC is set to TOC. The output from TOC is reset low by

MCU reset.

 Toggle output: The operation is basically the same as that of timer-B’s toggle output.

 0 output: The operation is basically the same as that of timer-B’s 0 output.

 1 output: The operation is basically the same as that of timer-B’s 1 output.

 PWM output: When PWM output mode is selected, timer C provides the variable-duty pulse output

function. The output waveform differs depending on the contents of timer mode register C1

(TMC1: $00D) and timer write register C (TWCL: $00E, TWCU: $00F). The output waveform is

shown in figure 43 (2).

Registers for Timer C Operation: By using the following registers, timer C operation modes are selected

and the timer C count is read and written.

 Timer mode register C1 (TMC1: $00D)

 Timer mode register C2 (TMC2: $014)

 Timer write register C (TWCL: $00E, TWCU: $00F)

 Timer read register C (TRCL: $00E, TRCU: $00F)

• Timer mode register C1 (TMC1: $00D): Four-bit write-only register that selects the free-running/reload

timer function, input clock source, and prescaler division ratio as shown in figure 52. It is reset to $0 by

MCU reset.

HD4048412FS Datasheet(PDF) 68 Page - Renesas Technology Corp