Renesas M16C/6NN Computer Hardware User Manual


 
Rev.1.02 Jul 01, 2005 page 288 of 314
REJ09B0126-0102
M16C/6N Group (M16C/6NL, M16C/6NN) 22. Usage Precaution
Under development
This document is under development and its contents are subject to change.
22.9.1.2 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.
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If a low-level signal is applied to the NMI pin when the IVPCR1 bit in the TB2SC register = 1 (three-
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phase output forcible cutoff by input on NMI pin enabled), the TA1OUT, TA2OUT and TA4OUT pins go
to a high-impedance state.