Altera High-Speed Development Kit, Stratix GX Edition - Manual (Page 105)

Altera Corporation Quartus II Version 3.0 7–23
Diagnostic Test Details Standard Tests
error flag and resets the counter. The error insertion pushbutton switch
inverts one bit in one data channel for one clock cycle, which is enough to
trigger the error detection circuit.
Stratix GX HM-Zd XCVR
This section describes the Stratix GX HM-Zd XCVR test. Refer to “Gigabit
Transceivers with HM-Zd Interface (Stratix GX HM-Zd XCVR)” on
page 5–18 for information on how to perform the test.
Stratix GX HM-Zd XCVR Test Overview
The transceiver HM-Zd design has a PLL, a 4 channel Altera GXB
transmitter/receiver block and a Verilog HDL block with the logic
required to generate a PRBS and verify that it was received correctly. The
design requires the transceiver HM-Zd loopback card to complete the
signal loopback.
f
For more information on the operation and parameterization of the GXB
megafuncion, refer to Quartus II Help or the Stratix GX FPGA Family
Data Sheet.
The top-level BDF lets you easily modify the system clock rate as desired
to evaluate a particular system configuration. By varying the GXB
megafunction parameters, you can adjust the per channel data rate up to
3,125 Mbps. The design has a Verilog HDL wrapper to name and place all
of the pins and to provide proper termination for the signals The
Stratix GX pushbutton switches control the start and stop of the data
transmission and reset the circuit. The LEDs indicate the start of
transmission, the start of reception of the valid data, the confirmation that
data was received correctly, and the reset condition.
The main system clock (parallel data rate) is derived from the
156.25-MHz crystal oscillator using the GXB megafunction clock output.
The data is generated in 20-bit words per channel using a PRBS generator
with a repetition count of 31, which results in a serial data rate of
3.125 Gbps. The data is then sent to a 4-channel version of the Altera GXB
megafunction, which converts the data into gigabit serial data streams.
The megafunction uses the basic protocol option.
The loopback card feeds the serial data back to the receive inputs on the
Stratix GX device. The data is converted back into parallel form by the
GXB megafunction. Because the design uses the double word feature of
the GXB megafunction, the byte alignment of the received data may be
incorrect. To adjust it, the data is sent through a byte swap block based on
synchronization data from the GXB megafunction. The data is then
passed to a pattern detection block to find the start of data in the PRBS