Renesas M16C/6NK Technical Information PDF herunterladen (Seite 149)

Rev.2.10 Apr 14, 2006 page 125 of 378

REJ09B0124-0210

M16C/6N Group (M16C/6NK, M16C/6NM) 13. Timers

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 (count starts) 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 (count stops)

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 undefined 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.

13.1.3 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 13.4 lists the One-shot Timer Mode Specifications.

Figure 13.11 shows Registers TA0MR to TA4MR in One-shot Timer Mode.

Table 13.4 One-shot Timer Mode Specifications

i = 0 to 4

j = i - 1, except j = 4 if i = 0

k = i + 1, except k = 0 if i = 4

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Renesas M16C/6NK Technical Information Seite 149