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33793 Datasheet PDF : 24 Pages
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Freescale Semiconductor, Inc.
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 4.
Table 4. Initialization Command Format
Data
Address
Command
CRC
NV BS G1 G0 PA3 PA2 PA1 PA0 A3 A2 A1 A0 0
0
0
0 X3 X2 X1 X0
Legend
A[3:0] = Address bits. The slave address.
BS = Bus Switch Position (1 = closed).
G[1:0] = Group bits (unused).
NV = Nonvolatile Memory Write. The value of the NV bit in the slave.
PA[3:0] = Bus Address to set the device to.
X[3:0] = Cyclic Redundancy Check (CRC). The CRC as calculated by the
master.
Initialization Response
This response message is sent during the next message
following a valid Initialization command to the addressed
device. The response is shown in Table 5. Because this is a
long-word only command, the short-word response is invalid.
Table 5. Initialization Response Format
High Byte
A3 A2 A1 A0 0
0
Low Byte
CRC
0 BF NV BS G1 G0 PA3 PA2 PA1 PA0 X3 X2 X1 X0
Legend
A[3:0] = Address bits. The slave address.
BF = Bus Fault. Bus out short to battery detected.
BS = Bus Switch Position (1 = closed).
G[1:0] = Group bits (unused).
NV = Nonvolatile Memory Write. The value of the NV bit in the slave.
PA[3:0] = Bus Address to set the device to.
X[3:0] = Cyclic Redundancy Check (CRC). The CRC as calculated by
the slave.
Request Status Command
This command will cause the addressed device to return the
status of the NV, U, and BS bits and the logic levels of the I/O
and LOGICOUT. The command format is found in Table 6.
Table 6. Request Status Command Format
Data
Address
Command
CRC
––––
–
–
–
– A3 A2 A1 A0 0 0 0 1 X3 X2 X1 X0
Legend
A[3:0] = Address bits. The address of the selected device. An
address value of "0000" is ignored by all devices.
X[3:0] = Cyclic Redundancy Check (CRC). The CRC as calculated
by the master.
MOTOROLA ANALOG INTEGRATED CIRFCoUrITMDEoVrIeCEIDnAfoTArmation On This Product,
Go to: www.freescale.com
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