IC-MD Datasheet, PDF (13/23 Pages) IC-Haus GmbH – ENCODER RECEIVER/COUNTER WITH SPI AND BiSS

iC-MD RS-422 QUADRATURE
preliminary
ENCODER RECEIVER/COUNTER WITH SPI AND BiSS
UPD REGISTER
Rev A1, Page 13/23
The register UPD is load at every index pulse with the
value of the "reference counter", it is the number of AB
edges between the last two index pulses (value of the
reference counter). It is used to check that any AB
pulse was lost.
The status bit UPDVAL (table 32) signals that a new
UPD value is available (UPD register was loaded and
still not read).
The following diagram shows the value of REF and
UPD after activating the zero codification function
when counting in negative direction.
5000
Z
Bit ZCEN=1
2510
REF
0
UPD
X
CNT
X
2490
Z
-2510
-2510
0+n
5005
5000
5005
5000
5005
2515
2485
2520
2480
2525
Z
Z
Z
Z
Z
Z
Negative counting direction
-2510
-2490
-2490+n
-2510
-2515
-2515+n
-2510
-2485
-5000+n
-2510
-2520
-5520+n
-2510
-2480
-10000+n
Figure 4: REF and UPD registers in negative direction