
preliminary
preliminary
iC-PVS
LINEAR/OFF-AXIS
BATTERY-BUFFERED ABSOLUTE POSITION HALL SENSOR
Rev A2, Page 38/51
EXTENDED SSI SLAVE INTERFACE
General protocol description
The SSI interface is an industry-standard serial com-
munications interface used for absolute position data
transmission. iC-PVS supports an extended SSI proto-
col (configurable data length, optional nERR, NWARN,
sign-of life counter and CRC), that can also be config-
ured to match the standard SSI format.
It can be activated by DIOMODE setting 0x1 or 0x2.
The absolute position data is transmitted as defined in
chapter Absolute Data Format on page 26. All values
are transmitted MSB first.
For Extended SSI the iC-PVS can provide a fixed or
adaptive timeout depending on the setting of parameter
NTOA_BISS (shared configuration parameter for BiSS
and Extended SSI).
!
The use of an adaptive timeout in SSI mode
is not recommended. Therefore NTOA_BISS
should be set to 1.
The SSI interface can also operate in external ring
mode by connecting SLO of the last slave in the SSI
chain to SLI of the first slave. This enables each SSI
frame to be transmitted twice. By checking the repeated
position data for equality, transmission errors can be
detected. Note that a stop zero is added between the re-
peated transmissions, requiring an additional SSI clock
cycle.
CLK: MA
SO: SLO
RC(39:0)
PC(15/7:0)
Frame
Idle
STOP
Cycle
Timeout
...
nERR
nWARN
LC(5:0)
CRC(5/15:0)
...
...
...
IPO(5:0)
...
Figure 18: Extended SSI Protocol