H838024 datasheet(301/697 Pages) RENESAS

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Section 9 Timers

Rev. 7.00 Mar 10, 2005 page 259 of 652

REJ09B0042-0700

During interval timer operation (TMC7 = 0), when a value is set in timer load register C (TLC),

the same value is set in TCC.

Note: For details on interrupts, see section 3.3, Interrupts.

Auto-Reload Timer Operation

Setting bit TMC7 in TMC to 1 causes timer C to function as an 8-bit auto-reload timer. When a

reload value is set in TLC, the same value is loaded into TCC, becoming the value from which

TCC starts its count.

After the count value in TCC reaches H'FF (H'00), the next clock signal input causes timer C to

overflow/underflow. The TLC value is then loaded into TCC, and the count continues from that

value. The overflow/underflow period can be set within a range from 1 to 256 input clocks,

depending on the TLC value.

The clock sources, up/down control, and interrupts in auto-reload mode are the same as in interval

mode.

In auto-reload mode (TMC7 = 1), when a new value is set in TLC, the TLC value is also set in

TCC.

Event Counter Operation

Timer C can operate as an event counter, counting rising or falling edges of an external event

signal input at pin TMIC. External event counting is selected by setting bits TMC2 to TMC0 in

timer mode register C (TMC) to all 1s (111). TCC counts up/down at the rising/falling edge of an

external event signal input at pin TMIC.

When timer C is used to count external event input, bit IRQ1 in PMRB should be set to 1 and bit

IEN1 in IENR1 cleared to 0 to disable interrupt IRQ1 requests.

TCC Up/Down Control by Hardware

With timer C, TCC up/down control can be performed by UD pin input. When bit TMC6 in TMC

is set to 1, TCC functions as an up-counter when UD pin input is low, and as a down-counter

when high.

When using UD pin input, set bit UD in PMR3 to 1.

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