UPD17062 datasheet(141/298 Pages) RENESAS

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139

µPD17062

(2) Timer error that occurs when the timer carry FF setting time interval is changed

The timer carry FF setting time interval is specified by the BTM0CK2, BTM0CK1, and BTM0CK0 flags in the

timer mode select register.

As shown in Fig. 12-1 and 12-2, the timer interval set pulse can be selected from 200 Hz, 10 Hz, and an external

timer.

These three pulses operate independently.

Therefore, when the timer interval set pulse is switched using the BTM0CK2, BTM0CK1, or BTM0CK0 flag,

a timer error occurs as shown in the following example.

Example

;

INITFLG

NOT BTM0ZX, NOT BTM0CK2, NOT BTM0CK1, NOT BTM0CK0

; Built-n macro

Process A

; Specifies the timer carry FF set pulse as 10 Hz (100 ms).

;

SET1

BTM0CK0 ; Built-in macro

; Specifies the timer carry FF set pulse as 200 Hz (5 ms).

Process A

;

CLR1

BTM0CK0 ; Built-in macro

; Specifies the timer carry FF set pulse as 10 Hz (100 ms).

With this coding, the timer carry FF set pulse is switched as shown below.

$SET1 BTM0CK0

%CLR1 BTM0CK0

SKT1 BTM0CY

Internal pulse 10 Hz

Internal pulse 200 Hz

Timer carry FF set pulse

BTM0CY flag

As shown above, when the timer carry FF setting time interval is switched, if a newly selected pulse goes

low, it allows the BTM0CY flag to preserve its previous state (

$ in the figure). If the pulse goes high, it sets

the BTM0CY flag to 1 (

% in the figure).

UPD17062 Datasheet(PDF) 141 Page - Renesas Technology Corp