Datasheet

iC-MA
8-BIT ANGULAR HALL SENSOR / ENCODER
Rev C1, Page 16/19
INCREMENTAL ABZ MODES
Mode NEN CFG1 CFG2 CFG3 Port A Port B Port C Port D Res. Comments
Incr. ABZ
ABZ 8-1 low low low open A B Z NERR 8 AB=1
ABZ 8-0 low open low open A B Z NERR 8 AB=0
ABZ 7-1 low low open open A B Z NERR 7 AB=1
ABZ 7-0 low open open open A B Z NERR 7 AB=0
ABZ 6-1 low low high open A B Z NERR 6 AB=1
ABZ 6-0 low open high open A B Z NERR 6 AB=0
ABZ 8-1 low low low high A B Z NERR 8 AB=1, PRM
ABZ 8-0 low open low high A B Z NERR 8 AB=0, PRM
ABZ 7-1 low low open high A B Z NERR 7 AB=1, PRM
ABZ 7-0 low open open high A B Z NERR 7 AB=0, PRM
ABZ 6-1 low low high high A B Z NERR 6 AB=1, PRM
ABZ 6-0 low open high high A B Z NERR 6 AB=0, PRM
iC-MA has an 8-bit sine/digital converter which can
convert the sine/cosine sensor signals into a digitized
angle. This angle is made available at the ports as an
incremental value. Signal Z is always high when the
angle is 0 °; otherwise the signal is low. In all incremen-
tal modes of operation error signal NERR is available
so that the plausibility of the counter value can be veri-
fied. At an amplitude which is less than 50 % of the set
amplitude the error signal level switches to low; at an
amplitude greater than 70 % the error signal is reset,
i.e. set to high.
Three different quantities regarding the number of
edges per rotation of the magnet can be selected.
These are a resolution of 6 bits (64 edges per rota-
tion), 7 bits (128 edges) or 8 bits (256 edges). The
conversion process is count-safe, i. e. the output of all
edges up to the current angle position is guaranteed as
long as the input frequency is less than the maximum
possible rotation.
All incremental resolutions also have a reduced power
consumption mode (PRM). In this mode the Hall sen-
sor is supplied with current intermittently, reducing the
power consumption. Here it must be noted that the
maximum input frequency drops by a factor of 2.
A distinction can be made between the various modes
of operation by studying the level of the AB signals on
the Z pulse. In mode AB = 1 signals A and B are both
high, as is Z at an angle of 0 °. In mode AB = 0, how-
ever, both signals A and B are low when the Z signal is
high.
Firstly, the behavior of the sensor on switching on the
device is described when the permanent magnet ro-
tates in the direction of the increasing angle ω (Fig-
ure 13). After switching on the sensor via NEN at low
level the sensor looks for its operating point. If 70 %
of the set amplitude is achieved the error signal is re-
set. An error status during this phase is also signaled
when signals A and B are high and Z= low. In an error-
free state Z level is always high when the angle is 0°.
iC-MA continues to search for its operating point by
outputting the angle of the external magnetic field at
maximum count frequency via the incremental inter-
face. Once the angle has been obtained the device
follows a changed input signal in real time. The edge
frequency is thus 256 times the frequency of rotation
of the magnet at a set resolution of 8 bits. If a (rising)
edge reaches B before a (rising) edge A, this means
that the counter value has risen. If the edge reaches
A before B, however, this indicates that the absolute
value is lower.
Time [us]
NEN
N
ERR
A
B
Z
Figure 13: Incremental signals after switching on
the device, counting up