M16C6S_09 Datasheet, PDF (193/208 Pages) Renesas Technology Corp – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

M16C/6S Group
Usage Notes
Timers
Timer A
Timer A (Timer Mode)
The timer remains idle after reset. Set the mode, count source, counter value, etc. using the TAiMR (i = 0
to 4) register and the TAi register before setting the TAiS bit in the TABSR register to 1 (count starts).
Always make sure the TAiMR register is modified while the TAiS bit remains 0 (count stops) regardless
whether after reset or not.
While counting is in progress, the counter value can be read out at any time by reading the TAi register.
However, if the TAi register is read at the same time the counter is reloaded, the read value is always
FFFF16. If the TAi register is read after setting a value in it, but before the counter starts counting, the read
value is the one that has been set in the register.
Timer A (Event Counter Mode)
The timer remains idle after reset. Set the mode, count source, counter value, etc. using the TAiMR (i = 0
to 4) register, the TAi register, the UDF register, bits TAZIE, TA0TGL, and TA0TGH in the ONSF register
and the TRGSR register before setting the TAiS bit in the TABSR register to 1 (count starts).
Always make sure bits TAZIE, TA0TGL, and TA0TGH in the TAiMR register, the UDF register, the ONSF
register, and the TRGSR register are modified while the TAiS bit remains 0 (count stops) regardless
whether after reset or not.
While counting is in progress, the counter value can be read out at any time by reading the TAi register.
However, if the TAi register is read at the same time the counter is reloaded, the read value is always
FFFF16 when the timer counter underflows and 000016 when the timer counter overflows. If the TAi
register is read after setting a value in it, but before the counter starts counting, the read value is the one
that has been set in the register.
Rev.5.01 Dec 10, 2009 page 193 of 201
REJ03B0014-0501