IC-MU_13 Datasheet, PDF (22/59 Pages) IC-Haus GmbH – OFF-AXIS NONIUS ENCODER WITH INTEGRATED HALL SENSORS

iC-MU OFF-AXIS NONIUS ENCODER
WITH INTEGRATED HALL SENSORS
preliminary
I2C INTERFACE AND STARTUP BEHAVIOR
Rev B1, Page 22/59
I2C interface / CRC
The multimaster-I2C interface enables read and write
access to a serial EEPROM which uses an address-
ing scheme equal to an 24C01 EEPROM (e.g. 24C02,
256 bytes, 5V type with a 3.3V function).
CRC8(7:0)
CRC8(7:0)
Code
...
Notes:
Addr. 0x2F; bit 7:0
Addr. SER: no access;
Meaning
CRC formed with CRC polynomial 0x197*)
*) x⁸ + x⁷ + x⁴ + x² + x¹ + 1, start value 0x1
The configuration data in the EEPROM in address
range 0x00 to 0x20 and 0x30 to 0x3F is checked with
a 16 bit CRC (CRC16). The start value for the CRC16
calculation is 1.
CRC16(7:0)
Addr. 0x21; bit 7:0
CRC16(15:8)
Addr. 0x22; bit 7:0
CRC16(15:0)
Addr. SER: no access;
Code
Meaning
...
CRC formed with CRC polynomial 0x11021*)
Notes:
*) x¹⁶ + x¹² + x⁵ + 1, start value 0x1
This is equivalent to CRC-CCITT/CRC-16
Table 24: EEPROM data checksum
The offset and preset position for iC-MU’s preset se-
quence is not part of the configuration data area. The
data is located in address range 0x23 to 0x2E of the
EEPROM and is checked separately with a 8-bit CRC
(CRC8). The start value for the CRC8 calculation is 1.
Table 25: Offset/preset data checksum
iC-MU calculates CRC8 and CRC16 automatically
when writing the configuration to the EEPROM. The
serial interface does not allow to access the CRC8
and CRC16 values. CRC16 and CRC8 are checked on
startup. A cyclic check during operation can be config-
ured with NCHK_CRC. With the command CRC_VER
(s. Tab. 97) a CRC check can be explicitly requested.
An error is signaled by status bit CRC_ERR.
NCHK_CRC
Addr. 0x0D; bit 6
Code
Meaning
0
cyclical CRC check of CRC16 and CRC8
1
no cyclical CRC check
Table 26: Zyclic CRC check