Auto-rate negotiation, Auto-rate negotiation -40 – Altera CPRI v6.0 MegaCore Function User Manual
Page 70
6. If the CPRI line bit rate is greater than 6.144 Gbps, increment the
tx_ctrl_seq
field of the
CTRL_INDEX
register to the value of 3 and write the fourth 32-bit section of the next intended #Z.X
control word to the
TX_CTRL
register.
7. If the CPRI line bit rate is 10.1376 Gbps, increment the
tx_ctrl_seq
field of the
CTRL_INDEX
register
to the value of 4 and write the fifth 32-bit section of the next intended #Z.X control word (the real-time
vendor specific bytes) to the
TX_CTRL
register.
8. Set the
tx_ctrl_insert
bit of the
CTRL_INDEX
register to the value of 1.
9. After you update the control transmit table, set the
tx_ctrl_insert_en
bit of the
L1_CONFIG
register
to enable the CPRI v6.0 IP core to write the values from the control transmit table to the control words
in the outgoing CPRI frame.
The
tx_control_insert
bit of the
CTRL_INDEX
register enables or disables the transmission of the
corresponding control transmit table entry in the CPRI frame. The
tx_ctrl_insert_en
bit of the
L1_CONFIG
register is the master enable: when it is set, the CPRI v6.0 IP core writes all table entries with
the
tx_ctrl_insert
bit set into the CPRI frame.
Example 3-2: Control Word Transmission Example
To write the vendor-specific portion of the control word in a transmitted hyperframe, perform
the following steps:
1. Identify the indices for the vendor-specific portion of the transmit control table, using the
formula X = Ns + 64 + Xs.
In the example, Ns = 16 and Xs = 0, 1, 2, and 3. Therefore, the indices to be read are 16, 80,
144, and 208.
2. For each value X in 16, 80, 144, and 208, perform the sequence of steps listed above.
After you update the control transmit table with the control bytes, to insert the data in the next
outgoing CPRI frame, make sure that you set the
tx_ctrl_insert_en
bit of the
L1_CONFIG
register to the value of 1 as specified in the instructions.
Auto-Rate Negotiation
If you turn on Enable auto-rate negotiation in the CPRI v6.0 parameter editor, the auto-rate negotiation
control and status interface is available. The CPRI v6.0 IP core provides support for dynamically changing
the CPRI line bit rate, but requires that you implement user logic to control the auto-rate negotiation
process. You control the process through the auto-rate negotiation control and status interface or the
BIT_RATE_CONFIG
register at offset 0x0C.
3-40
Auto-Rate Negotiation
UG-01156
2014.08.18
Altera Corporation
Functional Description