GRSPW_CODEC - SpaceWire Encoder Decoder
The GRSPW_CODEC core implements a SpaceWire encoder decoder with a 9-bit wide FIFO host interface in each direction. The core complies to the SpaceWire standard (ECSS-E-ST-12C). Data is transmitted and received through 9-bit wide FIFOs with configurable depth. The core also provides an interface for transmitting and receiving Time-codes as well as configuring the link properties such as speed.
For critical space applications, a fault-tolerant (FT) version of GRSPW_CODEC is available with full SEU protection of all RAM blocks
GRSPW_CODEC is the same codec as in the GRSPW2 but with a different host interface. Instead of using the advanced AMBA -AHB DMA and RMAP target a simple 9-bit wide FIFO interface is used instead. The host interface consists of 9-bit wide data interfaces to the FIFOs in both directions with accompanying read/write, full/character available and almost full/empty signals. The FIFOs can be configured from 16 to 2048 characters depth. Time-code transmission and reception is also supported using tickin/tickout and 8-bit timein/timeout signals.
The core properties and operation are controlled through a set of signals. They set the link speed during initialization and run-state, link interface FSM timeouts and control operations such as starting and disabling the link.
Compared to the GRSPW/GRSPW2 the core is useful in applications where the AMBA bus is not present, the source of data does not have an AMBA interface, low area is needed or when very detailed control of character transfer order and timing is needed.
Area and timing
The GRSPW_CODEC has been designed for high frequency operation even on slow technologies. The table below shows the approximate Cell/LUT count and frequency for three different GRSPW_CODEC configurations on Actel RTAX, RTProASIC3, Xilinx Virtex5 and ASIC technologies.
(Cells / RAM blocks / AHB MHz / SPW Rx Mbps)
|GRSPW_CODEC||1,800 / 2 / 40 / 295||2,400 / 2 / 45 / 206||700 / 2 / 100 / 400||6,000 gates|
|GRSPW_CODEC+2P(1)||2,000 / 2 / 40 / 295||2,800 / 2 / 45 / 206||760 / 2 / 100 / 400||7,000 gates|
|GRSPW_CODEC + 2P+FT(2)||2,100 / 2 / 40 / 295||2,900 / 2 / 45 / 206||800 / 2 / 100 / 400||7,400 gates|
(1)Dual SpaceWire ports. One is available in the standard configuration, (2) Fault tolerant version