rej05b0030_m16cap| Application Note
APPLICATION NOTE M16C/62A Group
Operation of Timer A (timer mode, gate function)
1.0 Abstract
In timer mode, choose functions from those listed in Table 1. Operations of the circled items are described below. Table 1. Choosed functions
Item Count source Pulse output function O O Set-up Internal count source(f1 / f8 / f32 / fc32) No pulses output Pulses output Gate function No gate function Performs count only for the period in which the TAiIN pin is at "L" level O Performs count only for the period in which the TAiIN pin is at "H" level
2.0 Introduction
Operation (1) When the count start flag is set to "1" and the TAiIN pin inputs at "H" level, the counter performs a down count on the count source. (2) When the TAiIN pin inputs at "L" level, the counter holds its value and stops. (3) If an underflow occurs, the content of the reload register is reloaded and the count continues. At this time, the timer Ai interrupt request bit goes to "1". (4) Setting the count start flag to "0" causes the counter to hold its value and to stop. Note Make the pulse width of the signal input to the TAiIN pin not less than two cycles of the count source.
Figure 1 shows the operation timing
n = reload register content FFFF16 n
Counter content (hex)
(1) Start count
(3) Underflow
(2) Stop count
(4) Stop count
Start count again. 000016 Set to "1" by software Cleared to "0" by software Time Set to "1" by software
Count start flag
"1" "0" "H" "L" Cleared to "0" when interrupt request is accepted, or cleared by software
TAiIN pin input signal
Timer Ai interrupt request bit
"1" "0"
Figure 1. Operation timing of timer mode, gate function selected
REJ05B0030-0100Z
May 2003
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