HD404449 Datasheet, PDF (69/125 Pages) Hitachi Semiconductor – HD404449 SERIES

HD404449 Series
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 R3₁/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.
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.
Writing to this register is valid from the second instruction execution cycle after the execution of the
previous timer mode register C1 write instruction. Setting timer C’s initialization by writing to timer
write register C (TWCL: $00E, TWCU: $00F) must be done after a mode change becomes valid.
• Timer mode register C2 (TMC2: $014): Three-bit read/write register that selects the timer C output
mode as shown in figure 53. It is reset to $0 by MCU reset.
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