33793 datasheet(15/27 Pages) FREESCALE

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Analog Integrated Circuit Device Data

Freescale Semiconductor

33793

FUNCTIONAL DEVICE OPERATION

DSI COMMANDS AND RESPONSES

INITIALIZATION COMMAND

The Initialization command must be sent to the 33793

before it may commence communications over the bus. The

command may be used three ways. The first is to initialize a

programmable address device. The second is the first step in

assigning a pre-programmed address. The third is to initialize

a pre-programmed device.

For the first case this command is sent to address zero

with the NV bit set to zero. The command will be received by

the next daisy chain device with its bus switch open.

Reception of this command will assign the device address

and group number.

For the second case the Initialization command is sent the

same as the first except that the NV bit is set to one.

Reception of the command will assign the device address

and group number. A Read/Write NVM command then may

be sent to complete the setting of a pre-programmed

address.

A pre-programmed device must be initialized by putting its

address in both PA3:PA0 and A3:A0 fields.

Once a device has received an initialization command, it

will ignore further initialization commands unless it has

received a Clear command or undergone a power-up reset.

If BS = 1 and no faults are detected, initialization will cause

the bus switch to close.

The command format is found in Table 9.

Table 8. Short-Word Response Summary

Command

Description

Response

0000

Initialization

Not Valid

0001

Request Status

IO3

IO2

IO1

IO0

0010

Request Value

0011

I/O Control

Not Valid

0100

Request ID Information

0101

Request Value

0110

Request Value

0111

Clear

No Response

1000

Request Value

1001

Read/Write NVM

Not Valid

1010

Reserved

1011

Reserved

1100

Clear Logic Out

IO3

IO2

IO1

IO0

1101

Set Logic Out

IO3

IO2

IO1

IO0

1110

Reserved

1111

Reverse Initialization

Not Valid

Legend

B[7:0] = 8-bit A/D value.

BS = Status of the Bus Switch (1 = close).

LO = Logic Out level at the Logic Out pin.

IO[3:0] = Logic level of I/O.

NV = Allows nonvolatile address programming if set to “1”.

PA[3:0] = Bus Address to set the device to.

U = Undervoltage Flag.

V[2:0] = Version number.

Table 9. Initialization Command Format

Data

Address

Command

CRC

PA3

PA2

PA1

PA0

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