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AEROFLEX GAISLER
60
RT-SPW-ROUTER
Copyright Aeroflex Gaisler AB
June 2012, Version 1.2
4
SpaceWire encoder-decoder
4.1
Overview
The SpaceWire encoder-decoder implements an encoder-decoder compliant to the SpaceWire stan-
dard (ECSS-E-ST-50-12C). It provides a generic host-interface consisting of control signals, status
signals, time-code interface and 9-bit wide data buses connecting to a pair of FIFOs.
The core is practically identical to the encoder-decoder used in the GRSPW2 the only difference
being the host-interface.
Note: The signals described in this section are internal only and cannot be accessed by the user of the
device. This section is provided for information only.
4.2
Operation
4.2.1
Overview
A block diagram of the internal structure of the core can be found in figure 11. It consists of the
receiver, transmitter and the link interface FSM. They handle communication on the SpaceWire net-
work. The PHY blocks provides a common interface for the receiver to the four different data recov-
ery schemes and is external to this core.
Time-codes are transmitted through a signal interface as specified in the SpaceWire standard.
4.2.2
Link-interface FSM
The link-interface FSM controls the link interface (a more detailed description is found in the
SpaceWire standard). The low-level protocol handling (the signal and character level of the
SpaceWire standard) is handled by the transmitter and receiver while the FSM handles the exchange
level.
The link-interface FSM is controlled through the control signals. The link can be disabled through the
link disabled signal, which depending on the current state, either prevents the link-interface from
Figure 11. Block diagram
TRANSMITTER
TXCLK
LINK INTERFACE
TRANSMITTER
D(1:0)
S(1:0)
FSM
RECEIVER0
FIFO
RECEIVER
FIFO
D0
S0
RECEIVER1
PHY
PHY
D
DV
D1
S1
D
DV
CONTROL SIGNALS
STATUS SIGNALS