33989 datasheet(21/66 Pages) FREESCALE

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Analog Integrated Circuit Device Data

Freescale Semiconductor

33989

FUNCTIONAL DEVICE OPERATION

OPERATIONAL MODES

When the application is in Stop mode (both MCU and

SBC), the application can wake-up from the SBC side (for

example: cyclic sense, forced wake-up, CAN message,

wake-up inputs and over current on VDD1), or the MCU side

(key wake-up, etc.).

Stop mode is always selected by the SPI. In Stop mode the

software Watchdog can be running or idle depending upon

selection by the SPI (RCR, bit WDSTOP). To clear the

watchdog, the SBC must be awakened by a CS pin (SPI

wake-up). In Stop mode, SBC wake-up capability are

identical as in Sleep mode. Please refer to Table 5.

SLEEP MODE

Regulators 1 and 2 are OFF. The current from VSUP pin is

reduced. In this mode, the device can be awakened internally

by cyclic sense via the wake-up inputs pins and HS1 output,

from the forced wake-up function and from the CAN physical

interface. When a wake-up occurs the SBC goes first into

reset mode before entering Normal Request mode.

RESET MODE

In this mode, the Reset (RST) pin is low and a timer is

running for a time RSTDUR. After this time is elapsed, the SBC

enters Normal Request mode. Reset mode is entered if a

reset condition occurs (VDD1 low, watchdog timeout or

watchdog trigger in a closed window).

NORMAL REQUEST MODE

This is a temporary mode automatically accessed by the

device after the reset mode, or after the SBC wake-up from

Stop mode. After wake-up from the Sleep mode or after the

device power-up, the SBC enters the Reset mode before

entering the Normal Request mode. After a wake-up from the

Stop mode, the SBC enters Normal Request mode directly.

In Normal Request mode the VDD1 regulator is ON, V2 is

OFF, the reset pin is high. As soon as the device enters the

Normal Request mode an internal 350 ms timer is started.

During these 350 ms the microcontroller of the application

must address the SBC via the SPI, configuring the Watchdog

timer and to go into the Normal or Standby mode and to set

the watchdog timer according to configuration.

NORMAL REQUEST ENTERED AND NO WD

CONFIGURATION OCCURS

In case the Normal Request mode is entered after SBC

power-up, or after a wake-up from Stop mode, and if no WD

configuration occurs while the SBC is in Normal Request

mode, the SBC goes to Reset mode after the 350 ms time

period is expired before again going into Normal Request

mode. If no WD configuration is achieved, the SBC

alternatively goes from Normal Request into reset, then

Normal Request modes etc.

In case the Normal Request mode is entered after a wake-

up from Sleep mode, and if no WD configuration occurs while

the SBC is in Normal Request mode, the SBC goes back to

Sleep mode.

APPLICATION WAKE-UP FROM SBC SIDE

When an application is in Stop mode, it can wake-up from

the SBC side. When a wake-up is detected by the SBC (for

example, CAN, Wake-up input, etc.) the SBC turns itself into

Normal Request mode and generates an interrupt pulse at

the INT pin.

APPLICATION WAKE-UP FROM MCU SIDE

When application is in Stop mode, the wake-up event may

come from the MCU side. In this case the MCU signals to the

SBC by a low to high transition on the CS pin. Then the SBC

goes into Normal Request mode and generates an interrupt

pulse at the INT pin.

STOP MODE CURRENT MONITOR

If the VDD1 output current exceed an internal threshold

(IDD1SWU), the SBC goes automatically into Normal Request

mode and generates an interrupt at the INT pin. The interrupt

is not maskable and the interrupt register will has no flag set.

INTERRUPT GENERATION WHEN WAKE-UP

FROM STOP MODE

When the SBC wakes up from Stop mode, it first enters the

Normal Request mode before generating a pulse (10 µs

typical) on the INT pin. These interrupts are not maskable,

and the wake-up event can be read through the SPI registers

(CANWU bit in Reset Control Register (RCR) and LCTRx bit

in Wake-Up Register (WUR). In case of wake-up from Stop

mode over current or from forced wake-up, no bit is set. After

the INT pulse the SBC accept SPI command after a time

delay (tS1STSPI parameter).

SOFTWARE WATCHDOG IN STOP MODE

If Watchdog is enabled, the MCU has to wake-up

independently of the SBC before the end of the SBC

watchdog time. In order to do this the MCU must signal the

wake-up to the SBC through the SPI wake-up (CS activation).

The SBC then wakes up and jumps into the Normal Request

mode. MCU has to configured the SBC to go to either Normal

or Standby mode. The MCU can then decide to go back again

to Stop mode.

When there is no MCU wake-up occurring within the

watchdog timing, the SBC activates the Reset pin, jumping

into the Normal Request mode. The MCU can then be

initialized.

STOP MODE ENTER COMMAND

Stop mode is entered at the end of the SPI message, and

at the rising edge of the CS. Please refer to the t CSSTOP data

in Dynamic Electrical Characteristics table on page 11.

Once Stop mode is entered the SBC could wake-up from

the V1 regulator over current detection. In order to allow time

for the MCU to complete the last CPU instruction, allowing

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