33793 Datasheet, PDF (15/27 Pages) Freescale Semiconductor, Inc – Distributed System Interface (DSI) Sensor Interface

FUNCTIONAL DEVICE OPERATION
DSI COMMANDS AND RESPONSES
Table 8. Short-Word Response Summary
Command
Command
Description
Response
0000
Initialization
0001
Request Status
0010
Request Value 0
0011
I/O Control
0100
Request ID Information
0101
Request Value 1
0110
Request Value 2
0111
Clear
1000
Request Value 3
1001
Read/Write NVM
1010
Reserved
1011
Reserved
1100
Clear Logic Out
1101
Set Logic Out
1110
Reserved
1111
Reverse Initialization
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.
Not Valid
NV
U
LO
BS
IO3
IO2
IO1
IO0
B7
B6
B5
B4
B3
B2
B1
B0
Not Valid
V2
V1
V0
0
0
0
1
1
B7
B6
B5
B4
B3
B2
B1
B0
B7
B6
B5
B4
B3
B2
B1
B0
No Response
B7
B6
B5
B4
B3
B2
B1
B0
Not Valid
NV
U
LO
BS
IO3
IO2
IO1
IO0
NV
U
LO
BS
IO3
IO2
IO1
IO0
Not Valid
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.
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 9. Initialization Command Format
Data
Address
NV BS G1 G0 PA3 PA2 PA1 PA0 A3 A2 A1 A0
Command
0000
CRC
X3 X2 X1 X0
Analog Integrated Circuit Device Data
Freescale Semiconductor
33793
15