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ADM1266

Data Sheet

Rev. A | Page 18 of 62

SEQUENCING ENGINE (SE)

OVERVIEW

The ADM1266 SE provides the user with powerful and flexible

control for sequencing multiple power rails. The SE implements

state machine control of the PDIOx and GPIOx outputs, with

state changes conditional on input events driven by VHx, VPx,

PDIO, GPIOs, timers, and variables. The SE programs can

enable complex control of boards such as power-up and power-

down sequence control, fault event handling, and interrupt

generation.

POWER-UP AND STATE 0

After the EEPROM data is downloaded, the ARM controller

starts execution of the core sequencer and transitions to the

following tasks, including but not limited to

•

Performing a roll call of all ADM1266 devices present if

more than 16 voltage rails are sequenced using more than

one ADM1266 device.

•

Checking the CRC status of the main and backup

configurations of all devices.

•

Synchronization of the black box ID between multiple

ADM1266 devices.

•

Waiting for a ready signal from all ADM1266 devices on

the IDB bus to enter State 1.

If a fault is present in any of these tasks, the SE halts and

terminates immediately. A power cycle or software reset using

GO_COMMAND (Register 0xD8) can restart the sequence

engine.

If all the operations of State 0 are successful, the device enters

State 1 where sequencing beings.

STATE SECTIONS

To maintain maximum flexibility and ease of use, the SE is

divided into two sections: enter actions and loop actions.

Enter Actions

The enter actions section consists of actions that are used to

initialize the system or a state. Examples range from starting

a timer to setting a PDIO. The actions programmed in this

subsection are executed only once before entering loop actions.

Loop Actions

In the loop actions section, the SE provides monitoring and

adjustment functions. After executing the enter actions, the

ADM1266 transitions and executes the actions in the loop

actions section. The device continues to execute these actions

in a loop, until it encounters a go to action. When the device

encounters a go to action, the device aborts the rest of the

actions in the loop actions and proceeds to the next state.

Whenever an interrupt is generated because of a fault or a logic

change, the SE is triggered to go to the first action in the loop

actions section and starts executing the actions. By ordering the

different actions in the loop actions, the user can set a priority

on when the actions are executed to minimize any delays.

ACTION TYPES

The user can configure multiple actions. These actions are

broadly classified into three categories: set actions, monitor

actions, and special actions.

Set Actions

Set actions set the output of a PDIO or GPIO. These actions can

also be used to set or reset variables and timers. These actions

can be configured in the enter actions and loop actions sections

of the state.

Monitor Actions

The fault monitoring action types are used to read the status of

the VHx, VPx, PDIOx, and GPIOx pins. The monitoring

function is extended to include the monitoring of the status of

variables and timers as well. The individual status is compared

to a threshold to determine the outcome of the action as true or

false. When the outcome is determined, an action is undertaken.

To expand on the flexibility of the sequence engine over

multiple rails, the user is allowed to program and monitor any

logical combination of rails, timers, PDIO, and GPIOs to create

a fault state.

Special Actions

Two special actions are available in the ADM1266. Use the go to

action to proceed to a preprogrammed state of the SE. Use the

black box action type to capture a snapshot of the status of all

the pins and write it to the EEPROM. Refer to the Black Box

(EEPROM) Fault Recording section for more details.

PARALLEL OPERATION AND INTERDEVICE BUS

If more than 16 rails are to be sequenced, multiple ADM1266

devices can be connected in parallel. Communication between

the ADM1266 devices is facilitated by the IDB that operates at

1 MHz maximum, and follows the I2C protocol. The IDB is a

private bus and sends Analog Devices proprietary messages. A

maximum of 16 ADM1266 devices can be connected on the IDB.

One device is configured as a master, and the other devices are

configured as slaves. All the slaves communicate their current

status back to the master; the master, based on the user config-

uration and the status of all the devices, broadcasts to all the

slaves the new state that they need to go to.

ADM1266ACPZ-R7 数据表(PDF) 18 Page - Analog Devices

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