Normal mil-std 1553

The norm MIL-STD-1553 describes a bus of communication series widely used in avionic military officer, as well as in satellites.  The first version of this norm was published in 1973; the current version is the version MIL-STD-1553B and dates back to 1978.

A databus “1553″ is a bus series.

* It is a matter of a data bus in the time.

* His physical support is an armored twisted pair of characteristic impedance 78 ohms.

* The norm defines two authorized types of raccordement:  “Long coupling stub” or “direct coupling”.

* The raccordements realize themselves using coupling transformers.

* The standard one defines the presence of a cable “A” and of a cable “B” in order to assure the redundance * the news coding is realized in “Manchester II bi-phase”.

* The tension level in go out of the transmitting one is inferior to 10 V.

* The length of a bit is 1 µs.

* THE minimal transmitted entity is 20 bits:  3 bits of sync (by code violation), 16 bits of data and a parity bit.

* The protocol is type “maitre-esclave” : all the communications are initiated by a “Bus Controler” or BC; the other connected entities are of the “Final Remote” or RT.

* The BC is often the computer of edge.

* The BC can be the RT of a more important network.

* The RT are the peripherals: instruments or actionneurs.

* 31 RT can be connected on a bus with the addresses of 0 to 30.  The address 31 is reserved to the messages of general broadcasting said “broadcast”.

* Every RT is composed from 30 under addresses (HIS).

* The BC initiates the transfer by an order is bc-rt (data sending to the RT or “receive”) is rt-bc (data recuperation originating RT or “transmit”).

* The BC also can initiate transfers rt-rt.

* The BC can equally initiate transfers of type “broadcast”, with a targeting message all the configured RT to accept the “broacast”.  This transfer type allows therefore to send simultaneously the same message to several RT.

* The transfer order indicates how many words, of 16 bits, will be transmitted.  A maximum of 32 words can be transmitted in an exchange.

* A statute word (or SW) accompanies every exchange.

* Besides the transfer orders, the BC can emit orders such as “Synchronize”, “Transmiter shutdown”, “Build in test”, etc.

The trumps of this databus are:

* It is deterministic

* It is sturdy to disruptions

* It is well adapted to his mission in his environment of avionic one even if, after 30 years, it begins showing its limits in terms of debit and of addressing.

* It is well known by the actors of the specific electronics to the airplanes and spatial vehicles

* It exists a component range harden to establish it: cables, connectors, bus coupler, coupling transformers, tranceiver, etc.  These components are qualified for military or spatial applications.  They bear a beach of extensive temperatures and withstand the radiations.

* It exists a manual defining the establishment methods, of qualification and of test:  MIL-HDBK-1553.

* Numerous there exist tools of perfect and of test.

* There exist the kernels of code VHDL, qualified, allowing establishing this protocol in FPGA or ASIC with functions of interface towards the electronics of the RT.