Datasheet

12. Timer A
puorG92/C61M
page 112
854fo7002,03.raM21.1.veR
2110-1010B90JER
Item Specification
Count source f1, f2, f8, f32, fC32
Count operation • Decrement
• When the counter reaches 0000 16 , 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 TAi register 000016 to FFFF16
However, the counter does not work if the divide-by-n value is set to 000016.
Count start condition TAiS bit in the TABSR register is set to 1 (start counting) and one of the
following triggers occurs.
• External trigger input from the TAiIN pin
• Timer B2 overflow or underflow,
timer Aj (j=i-1, except j=4 if i=0) overflow or underflow,
timer Ak (k=i+1, except k=0 if i=4) 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 000016
• TAiS bit is set to 0 (stop counting)
Interrupt request generation timing When the counter reaches 000016
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 TAi register
Write to timer • When not counting and until the 1st count source is input after counting start
Value written to TAi register is written to both reload register and counter
• When counting (after 1st count source input)
Value written to 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.
Table 12.4 Specifications in One-shot Timer Mode
12.1.3 One-shot Timer Mode
In one-shot timer mode, the timer is activated only once by one trigger. (See Table 12.4) When the
trigger occurs, the timer starts up and continues operating for a given period. Figure 12.11 shows the
TAiMR register in one-shot timer mode.