Balluff BIR 01- K15SL -000S15 Serie Manual De Instrucciones página 43

BIR 01- _ _ _ _ -K15SL _-000S15
Inductive Rapid Positioning System
7
SSI interface
7.1 Principle
SSI stands for Synchronous Serial Interface and describes
a digital synchronous interface with a differential clock line
and a differential data line. With the first falling clock edge,
the data word to be output is buffered in the BIR to ensure
data consistency. Data output takes place with the first
rising clock edge, i.e. the BIR supplies a bit to the data line
for each rising clock edge. In doing so, the line capacities
and delays of drivers tv when querying the data bits must
be taken into account in the controller.
The max. clock frequency f
Clk
length (see Technical data on 21, Fig. 10-1). The t
also called monoflop time, is started with the last falling
edge and is output as the low level with the last rising
edge. The data line remains at low until the t
elapsed. Afterwards, the BIR is ready again to receive the
next clock package.
SSIn
T
Clk
Clk
1 2
Data
MSB
T
Clk
Clk
t
v
Data
Clk
Data
T = 1/f SSI clock period, SSI clock frequency
Clk Clk
T = 1/f Sampling period, sampling rate
A A
n Number of bits to be transmitted (requires n+1 clock impulses)
t = 2 · T Time until the SSI interface is ready again
m Clk
t = 150 ns Transmission delay times (measured with a 1 m cable)
v
www.balluff.com
is dependent on the cable
time,
m
time has
m
3 4 5
t
v
T
A
The BIR works in asynchronous operation. If the minimum
sampling time is undercut, the BIR outputs the same
position value several times. The external sampling rate is
then greater than the internal rate. In addition, T
long enough so that the next clock package does not
occur in the t range of the previous package.
m
t
m
n n+1
LSB
must be
A
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