7643 datasheet(143/424 Pages) RENESAS

143 / 424 page

Rev.2.00

Aug 28, 2006

page 22 of 202

7643 Group

REJ09B0133-0200

APPLICATION

2.2 Timer

2.2.4 Notes on timer

(1) Read/Write for timer

•The timer division ratio is : 1 / (n + 1)

(n = “0” to “255” written into the timer)

•When the value is loaded only in the latch, the value is loaded in the timer at the count pulse

following the count where the timer reaches “0016”.

•In the timers 1 to 3, switching of the count sources of timers 1 to 3 does not affect the values

of reload latches. However, that may make count operation started. Therefore, write values again

in the order of timers 1, 2 and then timer 3 after their count sources have been switched.

•The timer current count value can be read out by reading the timer.

(2) Pulse output

•When using the TOUT output of timer 1 or timer 2, set bit 1 of port P5 direction register to “1”

(output mode).

•The TOUT output pin is shared with the XCOUT pin. Accordingly, when using f(XCIN)/2 as the timer 1

count source (bit 2 of timer 123 mode register = “0”), XCOUT oscillation drive must be disabled (bit

5 of clock control register = “1”) to input clocks from the XCIN pin.

•The P51/XCOUT/TOUT pin cannot function as an ordinary I/O port while XCIN-XCOUT is oscillating. When

XCIN-XCOUT oscillation is stopped or XCOUT oscillation drive is disabled, this can be used as the TOUT

output pin of timer 1 or 2.

(3)

STP instruction

When the reset or STP instruction is being executed, “0116” is set to the timer 2 and timer 2 latch,

and “FF16” is set to the timer 1 and timer 1 latch, and the timer 1 output is forcibly set as the timer

2 count source. Also, all bits except bit 4 of the timer 123 mode register (address 002916) are

initialized to “0”.

After returning from Stop Mode, reset the timer 1 (address 002416), timer 2

(address 002516), and the timer 123 mode register (address 002916).

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