HD404629R Datasheet, PDF (71/157 Pages) Renesas Technology Corp – AS Microcomputer Incorporating a DTMF Generator Circuit

HD404629R 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 run 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 R1₁/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 46.
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