33793 datasheet(20/27 Pages) FREESCALE

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Analog Integrated Circuit Device Data

Freescale Semiconductor

33793

FUNCTIONAL DEVICE OPERATION

DSI COMMANDS AND RESPONSES

SET LOGIC OUT COMMAND

The Set Logic Out command sets the Logic Out pin to a

logic high. The compliment to this command is the Clear

Logic Out. The Logic Out is cleared at power-up or following

a Clear command. The format of the Clear Logic Out

command is shown in Table 25.

SET LOGIC OUT RESPONSE

This response message is sent during the next message

following a valid Set Logic Out command to the addressed

device. The response is shown in Table 26. No response is

generated if the command address field was $0.

REVERSE INITIALIZATION

The Reverse Initialization is similar to the Initialization

command and will only work under the condition that it has

not already been initialized. 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 the group number. Reception of this command will also

cause the bus switch to close if BS = 1 and no fault is

detected.

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 the group number and cause the bus switch to close if BS

= 1 and there are no faults. 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 a reverse initialization

command, it will ignore further reverse initialization

commands or initialization commands unless it has received

a Clear command or undergone a power-up reset.

The command format is found in Table 27.

Table 25. Set Logic Out Command Format

Data

Address

Command

CRC

Legend

A[3:0] = Address bits. The address of the selected device.

X[3:0] = Cyclic Redundancy Check (CRC). The CRC as calculated by the

master.

Table 26. Set Logic Out Response Format

High Byte

Low Byte

CRC

IO3

IO2

IO1

IO0

Legend

A[3:0] - Address bits. The slave address.

BS = Bus Switch Position (1=closed)

IO[3:0] = Values at logic I/Os.

LO = Logic out driven level.

NV = Nonvolatile Memory Write. The value of the NV bit in the slave.

U = Undervoltage indicated true by a “1”.

X[3:0] = Cyclic Redundancy Check (CRC). The CRC as calculated by the

slave.

Table 27. Reverse Initialization Command Format

Data

Address

Command

CRC

PA3

PA2

PA1

PA0

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