MPC821 datasheet(187/242 Pages) NXP

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Functional Description

MOTOROLA

MPC860TFADS Daughter Board Design Specification—Rev 0.1

PRELIMINARY—SUBJECT TO CHANGE WITHOUT NOTICE

4 - Functional Description

In this chapter the various modules combining the MPC860TFADSDB are described to their design

details.

4•1

Reset & Reset - Configuration

There are 3 reset sources for the MPC:

1) Power-On ResetA

2) Hard Reset

3) Soft Reset

4•1•1

Power-On Reset

The Power - On Reset on the MPC860T-FADSB is generated out of 2 alternative power buses:

The keep alive power bus

The MAIN power bus.

Selection between the 2 options is done by means of jumper.

When option (1) above is selected, the power-on reset is generated by a dedicated voltage detector

made by Seiko the S-8051HN-CD-X with detection voltage range of 1.795 to 2.005V. During keep

alive power-on or when there is a voltage drop of that input into the above range Power-On Reset is

generated, i.e., PORESET* input of the MPC is asserted for a period of approximately 4 sec.

When option (2) above is selected, the power-on reset is generated by a dedicated voltage detector

made

by Seiko the S-8052ANY-NH-X with detection voltage range of 2.595V to 2.805V. During MAIN 3.3V

bus power-on or when there is a voltage drop of that input into the above range Power-On Reset is

generated, i.e., PORESET* input of the MPC is asserted for a period of approximately 4 sec. The

MAIN power on reset also generates power-on reset to all logic located on the motherboard.

When PORESET* is asserted to the MPC, the Power-On reset configuration is made available to

MPC. See 4•1•6•1 "Power - On Reset Configuration" on page 29 of MPC8XXFADS User’s Manual.

4•1•2

Hard Reset

Hard Reset is generated to the MPC860T by the following sources:

The MAIN power-on reset

Manual Hard Reset generated on the mother board

The debug port Hard reset

and by MPC860T’s internal sources.

When the open-drain signal Hard Reset is asserted, Hard reset configuration is driven on the data

bus by logic on the motherboard. See 4•1•6•2 "Hard Reset Configuration" on page 29 on

MPC8XXFADS User’s Manual.

4•1•3

Soft Reset

Soft Reset is generated to the MPC860T by the following sources:

The debug port controller located on the motherboard

Manual Soft Reset generated on the motherboard

A. In fact generated on the daughter board.

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

MPC821 Datasheet(PDF) 187 Page - NXP Semiconductors

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