AS-Interface Slave IC

AS2702 (SAP4.1)

Rev. C, January 2001

Page 14 of 18

If UOUT drops below VCOMOFF = nom. 10V data communication with the AS-interface bus is

aborted by the receiver or transmitter of the slave device. As long as U5R does not drop be-

low 3.75V in this situation, no ‘hard’ reset takes place; however the data communication

watchdog will be triggered (unless disabled) and a ‘soft’ reset will result.

((3520

AS2702 has a 16 x 8 Bits serial interface EEPROM on board to store the slave unit’s address

and set-up data in a non-volatile fashion.

The EEPROM stores the following data:

((3520

$GGUHVV

'DWD

5HOHYDQW 1U

RIELWV

3URJUDPPHGE\

1RWH

0, 1

Slave Address

5 + 1

Master (Initialization)

1

2

Settings (EID1)

4

Master (Initialization)

3

Settings (IO-Conf.)

5

Slave unit manufacturer

4

Settings (ID)

5

Slave unit manufacturer

5

Settings (EID2)

5

Slave unit manufacturer

6

Settings (Control-

Code)

5

Slave unit manufacturer

Note

1

6 Bits (A4, …, A0 + Sel-bit) in extended address mode: 62 slaves addressable;

5 Bits (A4, …, A0) in non-extended address mode: 31 slaves addressable

Obviously the capacity of the EEPROM is only partially used.

Reading and writing of the EEPROM is performed bytewise and trough temporary, volatile

registers.

Writing of data from the volatile register into the EEPROM takes about 10 ms per byte,

whereas reading takes less than 1 ms per byte.

Upon RESET the EEPROM info is read into temporary registers, including the slave’s address

which has been written redundantly into EEPROM locations 0 and 1 before.

The temporary registers receiving the address are compared for similarity; in case of non-

similarity – which e.g. may have been caused by a supply voltage dip during address writing –

the slave will flag non-regular operation status / slave address zero.