AS2702 – AS-Interface Slave IC

Revision 1.3, 21-Aug-08

Page 12 of 13

AS-Interface Bus Communication

All slaves connected to an AS-Interface bus are sequentially and cyclicly called by the master in a string of individual transactions

between the master and each slave unit.

A transaction consists of a 14 bits master request, typically containing the slave’s address as well as data or parameter info, and an

immediate acknowledging slave response of 7 bits.

The 14 bits master request – apart from Start Bit ST = 0 and End Bit EB = 1 – has the following contents:

•

1 Control Bit CB:

CB = 0 stands for data transfer (typ. data or parameters)

CB = 1 identifies command-type requests

•

5 Address Bits:

A4, …, A0

•

5 Information Bits:

I4, …, I0 (typ. data or parameters)

•

1 Parity Bit PB

AS2702 allows for up to 62 slaves on the same AS-Interface bus; this requires a slave address extended to 6 bits, hence an extra

bit beyond A4, …, A0.

select between A-slave (Sel = 0) and B-slave (Sel = 1) at address location A4, …, A0.

In non-extended address mode AS2702 is addressed with A4, …, A0 only – for a max. total of 31 slaves per AS-Interface bus

system, and is system compatible with existing slave device AS2701A.

The 7 bits slave response – apart from Start Bit ST = 0 and End Bit EB = 1 – has the following contents:

•

4 Information Bits:

I4, …, I0 (typ. data or parameters)

•

1 Parity Bit PB

Application Support

For general information and documentation on the AS-Interface concept you may contact the AS-Interface Association:

AS-International Association

Zum Taubengarten 52

D-63571 Gelnhausen

Tel.: +49-6051-473212

Fax: +49-6051-473282

Ordering Information

AS2702-20T

Package:

SOIC 20; delivery: tape & reel

AS2702-16T

Package:

SOIC 16W; delivery: tape & reel; no parameter port available

AS2702-20

Package:

SOIC 20; delivery: tubes

AS2702-16

Package:

SOIC 16W; delivery: tubes; no parameter port available