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GAISLER
4
GRSPW / GRSPW-FT
2
GRSPW - SpaceWire codec with AHB host Interface and RMAP target
2.1
Overview
The SpaceWire core provides an interface between the AHB bus and a SpaceWire network. It implements the SpaceWire standard (ECSS-E-ST-50-12A) with the protocol identification extension
(ECSS-E-ST-50-11C).The optional Remote Memory Access Protocol (RMAP) target implements the
ECSS standard (ECSS-E-ST-50-11C).
The core is configured through a set of registers accessed through an APB interface. Data is transferred through DMA channels using an AHB master interface.
Currently, there is one DMA channel but the core can easily be extended to use separate DMA channels for specific protocols. The core can also be configured to have either one or two ports.
There can be up to four clock domains: one for the AHB interface (system clock), one for the transmitter and one or two for the receiver depending on the number of configured ports. The receiver
clock can be twice as fast and the transmitter clock four times as fast as the system clock whose frequency should be at least 10 MHz.
The core only supports byte addressed 32-bit big-endian host systems.
TXCLK
D(1:0)
TRANSMITTER
S(1:0)
LINKINTERFACE
FSM
SEND
FSM
TRANSMITTER
FSM
RMAP
TRANSMITTER
TRANSMITTER
DMA ENGINE
AHB
MASTER INTERFACE
RECEIVER
DMA ENGINE
D0
S0
RXCLK RECEIVER0
RXCLK
RECOVERY
RMAP
RECEIVER
RECEIVER
AHB FIFO
RXCLK RECEIVER1
RXCLK
RECOVERY
N-CHAR
FIFO
RECEIVER DATA
PARALLELIZATION
REGISTERS
APB
INTERFACE
D1
S1
Figure 4. Block diagram
2.2
Operation
2.2.1
Overview
The main sub-blocks of the core are the link-interface, the RMAP target and the AMBA interface. A
block diagram of the internal structure can be found in figure 4.
The link interface consists of the receiver, transmitter and the link interface FSM. They handle communication on the SpaceWire network. The AMBA interface consists of the DMA engines, the AHB
master interface and the APB interface. The link interface provides FIFO interfaces to the DMA
engines. These FIFOs are used to transfer N-Chars between the AMBA and SpaceWire domains during reception and transmission.
Copyright Aeroflex Gaisler AB
December 2008, Version 1.0.2