Renesas M16C/6NK Hardware Manual page 369

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M16C/6N Group (M16C/6NK, M16C/6NM)
23.10.1.2 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, the TAZIE, TA0TGL and TA0TGH bits in the ONSF
register and the TRGSR register before setting the TAiS bit in the TABSR register to "1" (count starts).
Always make sure the TAiMR register, the UDF register, the TAZIE, TA0TGL and TA0TGH bits in 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, "FFFFh" can be read in underflow, while reloading, and "0000h" in overflow. When setting the
TAi register to a value during a counter stop, the setting value can be read before a counter starts
counting. Also, if the counter is read before it starts counting after a value is set in the TAi register while
not counting, the set value is read.
If a low-level signal is applied to the NMI pin when the IVPCR1 bit in the TB2SC register = 1 (three-
phase output forcible cutoff by input on NMI pin enabled), the TA1OUT, TA2OUT and TA4OUT pins go
to a high-impedance state.
Rev.2.00 Nov 28, 2005
REJ09B0124-0200
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23. Usage Precaution