IC-MB3 Datasheet, PDF (23/26 Pages) IC-Haus GmbH – BiSS INTERFACE MASTER, 1-Chan./3-Slaves

iC-MB3
BiSS INTERFACE MASTER, 1-Chan./3-Slaves
Rev D1, Page 23/26
At the end of communication in register mode the CDM timeout flag is set (address 243).
Error messaging
In sensor mode the validity of data is stored separately for each slave in the validity message register (address
241). In the event of error the appropriate validity message is deleted and nSENSERR set to 0 in the status
register. The error is signaled at pin NER.
In register mode a register error (nREGERR = 0) or a slave start signal missed for at least 4,096 MA1 clock
pulses results in an error message at NER. As following initialization no valid sensor data yet exists all the bits in
the validity message (address 241) are deleted; no display is generated at pin NER, however.
A watchdog error is triggered if during the automatic sensor data requests no new readout cycle was able to be
initiated. In this instance bit AGS is reset in the command register and the cyclic sensor data requests aborted.
A watchdog error is also triggered if a slave response is lacking during the transmission of register data. This has
two possible causes; either a slave does not respond to the first falling edge with a low or the slave fails to
generate a start bit.
It is possible to connect other components to pin NER which can also generate an error message; this can then
be read out via bit nERR in the status register at address 240.
Register communication in sensor mode (BiSS C-Mode)
In the BiSS C-Mode protocol it is possible to send register data to or receive register data from a slave during the
cyclic sensor data transmission. In conjunction with iC-MB3 the microcontroller must take care of control data
communications, and has to employ GETSENS0 and GETSENS1 to transmit the required CDM data.
For register data transmission in the opposite direction, from a sensor to the BiSS master, an additional bit is
introduced and filled in by the responding slave before the sensor data. So that the first data bit received is treated
as CDS, BiSSMOD1 must be set to 1 (address 237).