Altera CPRI IP Core - Manual (Page 126)

7–10 Chapter 7: Software Interface
CPRI Protocol Interface Registers
CPRI MegaCore Function December 2013 Altera Corporation
User Guide
Table 7–17. CPRI_RX_DELAY—Receiver Delay—Offset: 0x34
Field Bits Access Function Default
RSRV [31:(WIDTH_RX_BUF+2)] (1) UR0 Reserved. 0
rx_buf_delay [(WIDTH_RX_BUF+1):2] (1) RO
Current receive buffer fill level. Unit is 32-bit words.
Maximum value is 2
WIDTH_RX_BUF -1.
0
rx_byte_delay [1:0] RO
Current byte-alignment delay. This field is relevant
for the Rx path delay calculation. Refer to
“Rx Path
Delay Components” on page E–4 .
2'h0
Note to Table 7–17 :
(1) WIDTH_RX_BUF is the value specified for the Receiver buffer depth parameter. This value is log
2
of the depth of the Rx elastic buffer. By default,
it is set to six, specifying a 64-entry buffer. Altera recommends that you set it to four, specifying a 16-entry buffer, in slave configurations.
Table 7–18. CPRI_ROUND_DELAY—Round Trip Delay—Offset: 0x38
Field Bits Access Function Default
RSRV [31:20] UR0 Reserved. 12'h0
rx_round_trip_delay [19:0] RO
Measured round trip delay from cpri_tx_rfp to
cpri_rx_rfp . Unit is cpri_clkout clock periods.
20'h0
Table 7–19. CPRI_EX_DELAY_CONFIG—Extended Delay Measurement Configuration—Offset: 0x3C
Field Bits Access Function Default
RSRV [31:9] UR0 Reserved. 23'h0
ex_delay [8:0] RW
Integration period for Rx and Tx buffer extended delay measurement.
Program this field with the user-defined value N, where
M/N =
clk_ex_delay period / cpri_clkout period. Refer to
“Calculation Example: Rx Buffer Delay” on page E–8 .
9'h0
Table 7–20. CPRI_EX_DELAY_STATUS—Extended Delay Measurement Status—Offset: 0x40
Field Bits Access Function Default
RSRV [31] UR0 Reserved. 1'h0
tx_ex_buf_delay [30:18] RO
Tx buffer extended delay measurement
result. Unit is
cpri_clkout clock periods.
Refer to “Extended Tx Delay
Measurement” on page E–14 .
13’h0
RSRV [17] UR0 Reserved. 1'h0
ex_buf_delay_valid [16] RC
Indicates that the rx_ex_buf_delay and
tx_ex_buf_delay fields have been
updated.
1'h0
RSRV [15:(WIDTH_RX_BUF+9)] (1) UR0 Reserved. 0
rx_ex_buf_delay [(WIDTH_RX_BUF+8):0] (1) RO
Rx buffer extended delay measurement
result. Unit is
cpri_clkout clock periods.
Refer to “Extended Tx Delay
Measurement” on page E–14 .
0
Note to Table 7–20 :
(1) WIDTH_RX_BUF is the value specified for the Receiver buffer depth parameter. This value is log
2
of the depth of the Rx elastic buffer. By default,
it is set to six, specifying a 64-entry buffer. Altera recommends that you set it to four, specifying a 16-entry buffer, in slave configurations.