hd66100 Renesas Electronics Corporation., hd66100 Datasheet - Page 206

• Manufacturer Part Number: hd66100
• Description: H8/3867 Series
• Manufacturer: Renesas Electronics Corporation.

9.3.3
Timer Operation
1. Interval timer operation
When bit TMC7 in timer mode register C (TMC) is cleared to 0, timer C functions as an 8-bit
interval timer.
Upon reset, TCC is initialized to H'00 and TMC to H'18, so TCC continues up-counting as an
interval up-counter without halting immediately after a reset. The timer C operating clock is
selected from seven internal clock signals output by prescalers S and W, or an external clock input
at pin TMIC. The selection is made by bits TMC2 to TMC0 in TMC.
TCC up/down-count control can be performed either by software or hardware. The selection is
made by bits TMC6 and TMC5 in TMC.
After the count value in TCC reaches H'FF (H'00), the next clock input causes timer C to overflow
(underflow), setting bit IRRTC to 1 in IRR2. If IENTC = 1 in interrupt enable register 2 (IENR2),
a CPU interrupt is requested.
At overflow (underflow), TCC returns to H'00 (H'FF) and starts counting up (down) again.
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 3.3, Interrupts.
191