MC68HC05V12 Datasheet, PDF(139/246 Page) Freescale Semiconductor, Inc – HCMOS Microcontreller Unit

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MC68HC05V12 Datasheet, PDF (139/246 Pages) Freescale Semiconductor, Inc – HCMOS Microcontreller Unit

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Freescale Semiconductor, Inc.

Byte Data Link Controller â Digital (BDLCâD)

Functional Description

14.4.1.1 Power Off Mode

For the BDLC to guarantee operation, this mode is entered from reset

mode whenever the BDLC supply voltage, VDD, drops below its

minimum specified value. The BDLC will be placed in reset mode by low-

voltage reset (LVR) before being powered down. In power off mode, the

pin input and output specifications are not guaranteed.

14.4.1.2 Reset Mode

This mode is entered from power off mode whenever the BDLC supply

voltage, VDD, rises above its minimum specified value

(VDD â10%) and some MCU reset source is asserted. The internal MCU

reset must be asserted while powering up the BDLC or an unknown

state will be entered and correct operation cannot be guaranteed. Reset

mode is also entered from any other mode as soon as one of the MCUâs

possible reset sources (such as LVR, POR, COP watchdog, reset pin,

etc.) is asserted.

In reset mode, the internal BDLC voltage references are operative, VDD

is supplied to the internal circuits which are held in their reset state, and

the internal BDLC system clock is running. Registers will assume their

reset condition. Because outputs are held in their programmed reset

state, inputs and network activity are ignored.

14.4.1.3 Run Mode

This mode is entered from reset mode after all MCU reset sources are

no longer asserted. Run mode is entered from the BDLC wait mode

whenever activity is sensed on the J1850 bus.

Run mode is entered from the BDLC stop mode whenever network

activity is sensed, although messages will not be received properly until

the clocks have stabilized and the CPU is also in run mode.

In this mode, normal network operation takes place. The user should

ensure that all BDLC transmissions have ceased before exiting this

mode.

MC68HC05V12 â Rev. 2.0

Byte Data Link Controller â Digital (BDLCâD)

For More Information On This Product,

Go to: www.freescale.com

Technical Data

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