SH7708 datasheet(172/633 Pages) RENESAS

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8.7.2

Canceling Hardware Standby Mode

Hardware standby mode can only be canceled by a power-on reset.

When the CA pin is driven high while the

RESET pin is low and the BREQ pin is high, clock

oscillation is started. Hold the

RESET pin low until clock oscillation stabilizes. When the RESET

pin is driven high, the CPU begins power-on reset processing.

Hardware standby mode cannot be canceled by an interrupt or manual reset.

8.7.3

Hardware Standby Mode Timing

Figures 8.10 and 8.11 show examples of pin timing in hardware standby mode.

The CA pin is sampled using EXTAL2 (32.768 kHz), and a hardware standby request is only

recognized when the pin is low for two consecutive clock cycles.

The CA pin must be held low while the chip is in hardware standby mode.

Clock oscillation starts when the CA pin is driven high after the

RESET pin is driven low.

CKIO

RESET

STATUS

Normal

Standby

Reset

0 to 10 Bcyc

Undefined

Rcyc: EXTAL2 (32.768 kHz) cycle

2 Rcyc or more

Figure 8.10 Hardware Standby Mode Timing (When CA Goes Low in Normal Operation)

SH7708 bảng dữ liệu(PDF) 172 Page - Renesas Technology Corp