33793 Datasheet, PDF (20/27 Pages) Freescale Semiconductor, Inc – Distributed System Interface (DSI) Sensor Interface

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.
Table 25. Set Logic Out Command Format
Data
Address
Command
CRC
-
-
-
-
-
-
-
- A3
Legend
A[3:0] = Address bits. The address of the selected device.
A2 A1 A0 1
1
0
1 X3 X2 X1 X0
X[3:0] = Cyclic Redundancy Check (CRC). The CRC as calculated by the
master.
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.
Table 26. Set Logic Out Response Format
High Byte
A3 A2 A1 A0 0 0 0 0 NV
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.
Low Byte
CRC
U
LO BS IO3 IO2 IO1 IO0 X3 X2 X1 X0
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.
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 27. Reverse Initialization Command Format
Data
Address
Command
CRC
NV BS G1 G0 PA3 PA2 PA1 PA0 A3 A2 A1 A0 1 1 1 1 X3 X2 X1 X0
33793
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Analog Integrated Circuit Device Data
Freescale Semiconductor