TMP89FS60 datasheet(170/410 Pages) TOSHIBA

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Page 156

13. 16-bit Timer Counter (TCA)

13.4 Timer Function

TMP89FS60

RA001

13.4.4 Window mode

In the window mode, the up counter counts up at the rising edge of the pulse that is logical anded product of

the input pulse to the TCA0 pin (window pulse) and the internal clock.

13.4.4.1 Setting

Setting the operation mode selection TA0MOD<TA0M> to "101" activates the window mode. Select

the source clock at TA0MOD<TA0CK>.

Select the window pulse level at the trigger edge input selection TA0MOD<TA0TED>. Setting

TA0MOD<TA0TED> to "0" enables counting up as long as the window pulse is at the "H" level. Setting

TA0MOD<TA0TED> to "1" enables counting up as long as the window pulse is at the "L" level.

Note that this mode uses the TA0 input pin, and the TCA0 pin must be set to the input mode beforehand

in port settings.

The operation is started by setting TA0CR<TA0S> to "1". After the timer is started, writing to

TA0MOD and TA0CR<TA0OVE> is disabled. Be sure to complete the required mode settings before

starting the timer.

13.4.4.2 Operation

After the operation is started, when the level selected at TA0MOD<TA0TED> is input to the TCA0 pin,

the up counter increments according to the source clock selected at TA0MOD<TA0CK>. When a match

between the up counter value and the value set to timer register A (TA0DRA) is detected, an INTTA0

interrupt request is generated and the up counter is cleared to "0000H". After being cleared, the up counter

restarts counting.

The maximum frequency to be supplied must be slow enough for the program to analyze the count

value. Define a frequency pulse that is sufficiently lower than the programmed internal source clock.

Setting TA0CR<TA0S> to "0" during the timer operation causes the up counter to stop counting and be

TMP89FS60 Datasheet(PDF) 170 Page - Toshiba Semiconductor