ZAMC4100 datasheet(46/156 Pages) RENESAS

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ZAMC4100 Datasheet

January 26, 2016

3.5.3.

STANDBY Mode

In STANDBY Mode, the clock in the MCU is suspended rather than powered down. This MCU suspension

reduces power consumption (by a factor of two compared to the NORMAL Mode). Because the SBC analog

circuitry and MCU remain supplied, the system quickly returns to functionality when coming out from STANDBY

Mode.

The sequence of STANDBY Mode entry is shown in Figure 3.7. The MCU enables this mode by setting the STBY

bit in the SMDCTRL register (Table 3.5). After enabling the STANDBY Mode, the MCU firmware must execute a

dedicated clock gating instruction that will stop the MCU clock and therefore the program execution.

The MCU clock is enabled again if it receives an SBC interrupt on the IRQN line (see block diagram on page 4).

The interrupt can be generated by a LIN wake-up event or from another SBC peripheral event. The IRQN

interrupt generation automatically clears the STBY bit and the SBC switches to NORMAL Mode.

Note:

1) Before entering the STANDBY Mode, the MCU must clear all SBC interrupt flags in order to have the

IRQN line = ‘1’. Otherwise setting the STBY bit = 1 will not take effect.

2) When STANDBY Mode is enabled, all drivers are automatically disabled. If needed after wake-up, the

MCU should re-enable the drivers by setting the corresponding enable bits.

3) In order to have a LIN wake-up in STANDBY Mode, the interrupt enable bit LINIE in the IRQCTRL

3.5.4.

Supported Wake-up Sources

When the ZAMC4100 system is in SLEEP or STANDBY Mode, it returns to NORMAL operation mode when a

valid wake-up event is detected. The next sections describe the wake-up events supported by the ZAMC4100.

LIN Bus Wake-up

The wakeup detection protocol of the ZAMC4100 is based on the LIN 2.1 specification and discussed in detail in

section 3.13.2. The LIN wake-up detection is automatically enabled when SLEEP or STANDBY Mode is invoked.

When a LIN wake-up event occurs, it generates an interrupt that is indicated in the LINWUIF flag. Disabling the

LIN wake-up interrupt does not disable the wake-up event.

WDT Wake-up on MCU Reset Time-Out (STANDBY Mode)

This wake-up is generated only when the system is in STANDBY Mode and the watchdog timer is enabled to run

in STANDBY Mode. This is enabled by setting the WDTPMEN bit to ‘1’ in the SMDCTRL register (Table 3.5). If

the MCU reset time-out occurs it does not generate an MCU reset, only a wake-up event and return to NORMAL

Mode.

If the WDT interrupt is enabled, it is indicated by the WDTIF bit in the IRQSTAT register (

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