Eads Astrium SMCS332SpW User Manual
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SMCS332SpWUser ManualEADS Astrium GmbH, ASE2Doc No: SMCS_ASTD_UM_100Issue: 1.4Updated: 9-Sep-2006Page: 11 of 131– All Rights Reserved – Copyright per DIN 34 –2.2 Operation ModesAccording to the different protocol formats expected for the operation of the SMCS332SpW, two major operation modes areimplemented into the SMCS332SpW. The operation modes are chosen individually for each link channel by setting therespective configuration registers via the HOCI or via the link.• Transparent Mode (default after reset): This mode allows complete transparent data transfer between two nodeswithout performing any interpretation of the data bytes and without generating any acknowledges. It is completelyup to the host CPU to interpret the received data and to generate acknowledges if required.The SMCS332SpW accepts EOP and EEP control tokens as packet delimiters and generates autonomously EOP orno EOP (as configured) marker after each end of a transmission packet.This mode also includes as a special sub mode:• Wormhole routing: This mode allows hardware routing of packets by the SMCS332SpW.• Simple Interprocessor Communication (SIC) Protocol Mode: This mode executes the simple interprocessorcommunication protocol as described in chapter 13. The following capabilities of the protocol are implemented intothe SMCS332SpW:• interpretation of the first 4 data characters as the header bytes of the protocol• autonomous execution of the simple control commands as described in the protocol specification• autonomous acknowledgement of received packets if configuredIn transmit direction no interpretation of the data is performed. This means that for transmit packets, the four headerbytes must be generated by the host CPU and must be available as the first data read from the communicationmemory. EOP control characters are automatically inserted by the SMCS332SpW if one configured transfer fromthe communication memory has finished.2.3 SMCS332SpW Control by SpaceWire linkA feature of the SMCS332SpW is the possibility to control the SMCS332SpW not only via HOCI but via one of the threelinks. This allows to use the SMCS332SpW in systems without a local controller (μController, FPGA etc.). Since the HOCIis no longer used in this operation mode, it is instead available as a set of general purpose I/O (GPIO) lines. The detaileddescription of this operation mode is given in section 5.4.2.4 Wormhole RoutingThe SMCS332SpW introduces a wormhole routing function similar to the routing implemented in the SpaceWire Router.Each of the three links and the SMCS332SpW itself can be assigned an eight bit address. When routing is enabled in theSMCS332SpW, the first byte of a packet will be interpreted as the address destination byte, analyzed and removed from thepacket (header deletion). If this address matches one of the two other link addresses or the SMCS332SpW address assignedpreviously, the packet will be automatically forwarded to this link or the FIFO of the SMCS332SpW. If the header byte doesnot match a link address, the packet will be written to the internal FIFO as well and an error interrupt (maskable) will beraised. |
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