Direct hdlc serial interface, Direct hdlc serial interface -27 – Altera CPRI v6.0 MegaCore Function User Manual
Page 57
Figure 3-19: Direct RTVS TX Timing Diagram
Expected behavior on the direct RTVS TX interface of a CPRI v6.0 IP core running at 10.1376 Gbps.
The
aux_tx_x
and
aux_tx_seq
signals are not part of this interface and are available only if you turn on
the AUX interface in your CPRI v6.0 IP core variation. However, their presence in the timing diagram
explains the timing of the
rtvs_tx_ready
output signal that you use to identify the clock cycles when you
can write RTVS data to the CPRI frame.
Note that the write latency is one
cpri_clkout
clock cycle in this example.
cpri_clkout
100
101
124
7
4
6
aux_tx_x
aux_tx_seq
rtvs_tx_ready
rtvs_tx_valid
X
D1D2D3D4
X
rtvs_tx_data[31:0]
5
4
3
2
1
0
79
3
2
1
0
Auxiliary latency cycle(s) == 0
Related Information
For more information about the Avalon-ST protocol, including timing diagrams, refer to the Avalon
Streaming Interfaces chapter.
Direct HDLC Serial Interface
If you turn on Enable direct HDLC serial interface in the CPRI v6.0 parameter editor, the direct HDLC
serial interface is available. This interface allows direct access to the slow control and management data in
the CPRI frame. You can connect this interface to a user-defined HDLC PCS and MAC.
This interface is Avalon-ST compliant with a read latency value of 1.
You can alter the transmit write latency with the Auxiliary latency cycle(s) parameter. However, you do
not need to view the
aux_tx_seq
signal for correct alignment. You can monitor the
hdlc_rx_valid
and
hdlc_tx_ready
signals to discover the correct times to read and write data on this interface.
Table 3-9: Direct HDLC Serial Interface Signals
All interface signals are clocked by the
cpri_clkout
clock.
Direct HDLC Serial RX Interface
Signal Name
Direction
Description
hdlc_rx_valid
Output
When asserted, indicates
hdlc_rx_data
holds a valid
HDLC bit in the current clock cycle.
UG-01156
2014.08.18
Direct HDLC Serial Interface
3-27
Functional Description
Altera Corporation