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Rev.1.02 Jul 01, 2005 page 100 of 314
REJ09B0126-0102
M16C/6N Group (M16C/6NL, M16C/6NN) 12. Timers
Under development
This document is under development and its contents are subject to change.
Item Specification
Count Source f1, f2, f8, f32, fC32
Count Operation • Down-count
• When the counter reaches 0000h, it stops counting after reloading a new value
• If a trigger occurs when counting, the timer reloads a new count and restarts counting
Divide Ratio 1/n n : set value of the TAi register 0000h to FFFFh
However, the counter does not work if the divide-by-n value is set to 0000h.
Count Start Condition The TAiS bit in the TABSR register = 1 (start counting) and one of the following
triggers occurs.
• External trigger input from the TAiIN pin
• Timer B2 overflow or underflow,
Timer Aj overflow or underflow,
Timer Ak overflow or underflow
• The TAiOS bit in the ONSF register is set to “1” (timer starts)
Count Stop Condition • When the counter is reloaded after reaching “0000h”
• TAiS bit is set to “0” (stop counting)
Interrupt Request Generation Timing
When the counter reaches “0000h”
TAiIN Pin Function I/O port or trigger input
TAiOUT Pin Function I/O port or pulse output
Read from Timer An indeterminate value is read by reading the TAi register
Write to Timer • When not counting and until the 1st count source is input after counting start
Value written to the TAi register is written to both reload register and counter
• When counting (after 1st count source input)
Value written to the TAi register is written to only reload register
(Transferred to counter when reloaded next)
Select Function • Pulse output function
The timer outputs a low when not counting and a high when counting.
12.1.3 One-shot Timer Mode
In one-shot timer mode, the timer is activated only once by one trigger. When the trigger occurs, the timer
starts up and continues operating for a given period. Table 12.4 lists specifications in one-shot timer
mode. Figure 12.11 shows the TAiMR register in the one-shot timer mode.
Table 12.4 Specifications in One-shot Timer Mode
i = 0 to 4
j = i - 1, except j = 4 if i = 0
k = i + 1, except k = 0 if i = 4