iC-MB3

BiSS INTERFACE MASTER, 1-Chan./3-Slaves

Rev D1, Page 18/26

DATA STORAGE - Sensor Data

So that new sensor data can be read in during controller accesses iC-MB3 has dual memory banks for sensor

data. While sensor data is being read into the first RAM, from the second RAM section the controller can read out

the sensor data last read in. The relevant sensor data memory banks are swapped over at the end of the readin

procedure; this can be prevented by the controller entering the command register bit UCREADSENS. In parallel

with this the validity message register (address 241) and bit REG(address 248) are also swapped.

Arrangement of sensor data in the RAM

The sensor data memory bank has 8 bytes of memory for each slave which can be interpreted as 64 bits of

memory in the array xxxxx111b to xxxxx000b. The sensor data is written to memory area [SDLEN - 1:0] with

SDLEN marking the length of the relevant data. Should there be room in the available memory for the CRC bits,

these are then also stored with the above data at positions [63:63 - (CRCLEN-1)].

Example Slave 2: 20 bits of sensor data, 6 bits of CRC

=> total length of 26 bits

Adr. 07 ... 00:

Sensor data Slave 1

Adr. 15 ... 08:

Sensor data Slave 2 -

Adr. 15:

SensCRC(5:0), not defined, not defined

Adr. 14:

- not defined -

Adr. 13:

- not defined -

Adr. 12:

- not defined -

Adr. 11:

- not defined -

Adr. 10:

not defined, not defined, not defined, not defined, SensData(19:16)

Adr. 9:

SensData(15:8)

Adr. 8:

SensData(7:0)

Adr. 23 ... 16:

Sensor data Slave 3

...

DATA STORAGE - register data

For the interim storage of register information read out from or to be written to the slaves iC-MB3 has an individual

storage area (addresses 128 to 159) which can temporarily store up to 32 bytes of data. With just one single

command this is then transmitted to a slave selected using SLAVEID(2:0) or requested from it as register data.

The transmission of register data takes longer than that of sensor data so that the content of the sensor data RAM

is then often obsolete.