33793 Datasheet, PDF (17/27 Pages) Freescale Semiconductor, Inc – Distributed System Interface (DSI) Sensor Interface

FUNCTIONAL DEVICE OPERATION
DSI COMMANDS AND RESPONSES
Table 13. Request Value n Command Format
Data
Address
Command
CRC
–
–
–
–
–
–
–
– A3 A2 A1 A0 C3 C2 C1 C0 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.
C[3:0] = Command number.
X[3:0] = Cyclic Redundancy Check (CRC). The CRC as calculated by the
master.
Table 14. Analog Input Selection
Command
A/D Input
0010
I/O0
0101
I/O1
0110
I/O2
1000
I/O3
REQUEST VALUES RESPONSE
This response is an 8-bit value representing the value
measured by the ADC. The selection of “n” is a function of the
command. This is shown in Table 15.
The read will be completed during the idle period and will
represent the voltage at the end of the command. If an
undervoltage condition exists at any time during the
command or the measurement has not completed properly, a
value of “00000000” will be returned. This is a reserved value
to indicate a problem with the measurement. The minimum
valid level reported will be “00000001”. No response is
generated if the command address field was $0.
Table 15. Request Values Response Format
High Byte
Low Byte
CRC
A3 A2 A1 A0 0 0 0 0 D7 D6 D5 D4 D3 D2 D1 D0 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.
D[7:0] = Measured value (MSB = D7).
X[3:0] = Cyclic Redundancy Check (CRC).
I/O CONTROL COMMAND
This register controls the I/O ports. When the “DR” bits are
set, the corresponding I/O is enabled as an output. The “L” bit
settings control the level of the corresponding I/O if it is
enabled as an output. The format of this command is shown
in Table 16.
Table 16. I/O Control Command Format
Data
Address
Command
CRC
L3 L2 L1 L0 DR3 DR2 DR1 DR0 A3
Legend
A[3:0] = Address bits.
DR[3:0] = I/O direction bits. 1 = Output. All bits are set to “0” by
reset/clear.
A2 A1 A0 0 0 1 1 X3 X2 X1 X0
L[3:0] = Level to output on I/O if configured as output. All bits are set to “0”
by reset/clear
X[3:0] = Cyclic Redundancy Check (CRC). The CRC as calculated by the
master.
I/O CONTROL RESPONSE
The response indicates which I/O has been configured as
outputs and their current values.
Table 17. I/O Control Response Format
High Byte
The values returned will be the values programmed. The
values at the pins will not be the ones that were programmed
if the pin has been forced to the opposite state. The response
format is shown in Table 17. No response is generated if the
command address field was $0.
Low Byte
CRC
Analog Integrated Circuit Device Data
Freescale Semiconductor
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