Python functions for PRBS testing:
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disable_oversampling_in_gen1()
rate_and_preset_settings()
gty_tx_rx_reset()
prbs_sync()
ber_counter_reset()
snap_ber_counters()
enable_oversampling_in_gen1()
disable_bist()
description: disable_oversampling_in_gen1() :
Disables oversampling in Gen1
rate_and_preset_settings(rate, link_width = 4, is_external_loopback = 1, tx_amplitude_swing = 950)::
Sets the user specified data rate for Transceiver. Sets the user specified linkwidth for
Transceiver, rest on all the lanes tx_electrical_idle will be transmitted. LTSSM cannot control the
Transceiver when this function is called. Enables bist path of transceiver.
This function has the following arguments.
rate - data rate at which the transceiver should work
Valid values are 0,1,2,3,4,5. With 0 being gen1 , 4 being gen5 and 5 being gen6
link_width- Link width
Valid values are 0,1,2,3,4. With 0 being x1 , 1 being x2 and 4 being x16
gty_tx_rx_reset(tx_reset,rx_reset) :
issues reset to transceiver.
Arguments:
tx_reset : to issue reset to tx side 0  do not reset tx path , 1  reset the tx path
rx_reset : to issue reset to rx_side 0  do not reset tx path , 1  reset the tx path
prbs_sync() :
isssues sync to prbs checker
ber_counter_reset():
resets the ber counters in prbs checker
snap_ber_counters() :
reads BER counter values of each lanes one after other.
enable_oversampling_in_gen1() :
enables oversampling in Gen1
disable_bist() :
Enables the LTSSM to control the Transceiver, disable BIST path of transceiver.
Testing procedure :
1. configure FPGA from vivado
2. connect python session with 64 bit python
3. disable the oversampling in Gen1 by calling disable_oversampling_in_gen1()
4. configure Gen6 data rate by calling rate_and_preset_settings(5).
5. Issue rx_reset to transceiver by calling gty_tx_rx_reset(0,1)
6. Issue a PRBS sync to the checker prbs_sync()
7. Issue a BER reset by calling ber_counter_reset()
8. Capture the BER counters by calling snap_ber_counters()
To switch back to LTSSM data, call enable_oversampling_in_gen1(),
IBERT observation:
IBERT setting :
Tx_pattern: PRBS_23
Rx_pattern: PRBS_23
Tx_precursor: 0
Tx_precursor2: 0
Tx_postcursor: 0
Loopback mode: None
TX main cursor: 0.998vdd
Observed BER 10^-8
disable_bist()