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