SH7708 datasheet(353/633 Pages) RENESAS

No. de pieza	SH7708

Descripción Electrónicos	SuperH??RISC engine

PDF	633 Pages

Scroll/Zoom	100%

Fabricante Electrónico	RENESAS [Renesas Technology Corp]

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12.3.3

Reading the Time

Figure 12.3 shows how to read the time. If a carry occurs while reading the time, the correct time

will not be obtained, so it must be read again. Part (a) in figure 12.3 shows the method of reading

the time without using interrupts; part (b) in figure 12.3 shows the method using carry interrupts.

To keep programming simple, method (a) should normally be used.

Write 0 to CF in RCR1

Note: Set AF to 1 so that alarm

flag is not cleared.

Write 0 to CIE in RCR1

Read RCR1 and check CF

Write 0 to CIE in RCR1

Carry flag = 1?

Yes

Clear the carry flag

Disable the carry

interrupt

Read counter

Write 1 to CIE in RCR1,

and write 0 to CF in RCR1

Note: Set AF in RCR1 to 1 so that

alarm flag is not cleared.

Interrupt

generated?

Yes

Enable the carry

interrupt

Clear the carry flag

Disable the carry

interrupt

Read counter

To read the time

without using interrupts

b. To use interrupts

Figure 12.3 Reading the Time

SH7708 Datasheet(PDF) 353 Page - Renesas Technology Corp