IC-MHM Datasheet, PDF (37/63 Pages) IC-Haus GmbH – 14-BIT ABSOLUTE ANGLE HALL ENCODER

iC-MHM
14-BIT ABSOLUTE ANGLE HALL ENCODER
SERIAL INTERFACE: BiSS Mode
Rev D1, Page 37/63
The BiSS interface is an open-source differential, serial,
bidirectional communications interface used for abso-
lute position and configuration data transmission. In
BiSS mode, the iC-MHM is a BiSS slave and must be
connected to a BiSS master for proper operation. For a
detailed description of the BiSS Interface, please refer
to www.biss-interface.com.
The serial interface is configured for BiSS mode by dis-
abling SSI mode ENSSI = 0 and requires
DISBiSS = 0.
DISBISS
Value
0
1
Addr. 0x07; bit 5
Description
BiSS Enabled
MISO (SLO) Driven High When NCS Inactive
BiSS Disabled
MISO (SLO) in Tristate (High Z) When NCS Inactive
Table 62: Disable BiSS Interface
The BiSS serial protocol used by the iC-MHM is shown
in Figure 21.
ENSSI
Value
0
1
Address 0x03; bit 7
Serial Mode
BiSS C
SSI
Table 61: BiSS/SSI Protocol Selection
After every BiSS cycle, the integrity of the configuration
and offset data is verified using a CRC. If either CRC
fails, the appropriate error bit in the error status register
is set, the error output is activated (pin NERR low), and
the BiSS error bit is activated (nERR = 0) for the next
cycle. Refer to STATUS REGISTERS on page 30 for
more information.
Figure 21: BiSS Protocol
BiSS Single Cycle Data (SCD)
The Single Cycle Data (SCD) produced by the iC-MHM,
shown in blue in Figure 21, contains the multiturn po-
sition (turns count) followed by the singleturn position
(magnet angle), an error bit, a warning bit, an optional
sign-of-life counter value, and a CRC value. All values
are transmitted MSB first in the order shown in
Table 63.
Single Cycle Data (SCD)
Bit Length Description
0 - 32
Multiturn Position (Turns Count - OFFS_MT)
12 or 16 Singleturn Position (Magnet Angle - OFFS_ST)
1
Error Bit nERR (Active Low)
1
Warning Bit nWARN (Active Low)
0 or 6
Optional Sign-of-Life Counter
(BiSS SCD Cycle Count)
6 or 16
CRC Polynomial (Inverted)
The bit length of the multiturn count in the BiSS SCD is
set using parameter MT12.
MT12
Value
0
1
1
1
1
Address 0x03; bit 2
Multiturn Bit Length
As Defined by
RESO_MT
0
12
24
32
Conditions
RESO_MT = 0
RESO_MT = 1, 2, or 3
RESO_MT = 4, 5, or 6
RESO_MT = 7
Table 64: Multiturn Bit Length
When using BiSS Encoder Profile BP3, set MT12 = 0.
In this case, the multiturn count bit length is set by pa-
rameter RESO_MT. Refer to MULTITURN INTERFACE
on page 23 for more information on RESO_MT.
Table 63: iC-MHM BiSS Single Cycle Data
Refer to POSITION OFFSET AND PRESET (Zero Po-
sition) on page 55 for more information on the position
offset parameters OFFS_MT and OFFS_ST.
When using BiSS Encoder Profile BP1, set MT12 = 1. In
this case, the multiturn position bit length still depends
on RESO_MT, but is always fixed at 0, 12, 24, or 32.
If the multiturn resolution (in bits) is less than one of
these values, the multiturn count value is right-justified