To support deterministic latency with non-power of two octets per frame
(F=3,6) the interface width towards the transport layer must be resized
to match integer multiple of frames.
e.g Input datapath width = 4; Output datpath width = 6;
for F=3 one beat contains 2 frames
for F=6 one beat contains 1 frame
The width change is realized with a gearbox.
Due the interface width change the single clock domain core is split
in two clock domains.
- Link clock : lane rate / 40 for input datapath width of 4 octets 8b10b
- lane rate / 20 for input datapath width of 8 octets 8b10b
- lane rate / 66 for input datapath width of 8 octets 64b66b
- Device clock : Link clock * input data path width / output datapath width
Interface to transport layer and SYSREF handling is moved to device clock domain.
The configuration interface reflects the dual clock domain.
If Input and Output datapath width matches, the gearbox is no longer
required, a single clock can be connected to both clocks.
For consistent simulation behavior it is recommended to annotate all source
files with a timescale. Add it to those where it is currently missing.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
The ADI JESD204 link layer cores are a implementation of the JESD204 link
layer. They are responsible for handling the control signals (like SYNC and
SYSREF) and controlling the link state machine as well as performing
per-lane (de-)scrambling and character replacement.
Architecturally the cores are separated into two components.
1) Protocol processing cores (jesd204_rx, jesd204_tx). These cores take
care of the JESD204 protocol handling. They have configuration and status
ports that allows to configure their behaviour and monitor the current
state. The processing cores run entirely in the lane_rate/40 clock domain.
They have a upstream and a downstream port that accept and generate raw PHY
level data and transport level payload data (which is which depends on the
direction of the core).
2) Configuration interface cores (axi_jesd204_rx, axi_jesd204_tx). The
configuration interface cores provide a register map interface that allow
access to the to the configuration and status interfaces of the processing
cores. The configuration cores are responsible for implementing the clock
domain crossing between the lane_rate/40 and register map clock domain.
These new cores are compatible to all ADI converter products using the
JESD204 interface.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Laszlo Nagy
Lars-Peter Clausen