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AR# 32096

10.1 EDK SP3, XPS_LL_TEMAC_v1_01_b - Can the XPS_LL_TEMAC Core operate at gigabit speeds in a Spartan device?


Keywords: sp3adsp1800, dsp, strarter, starter, kit, throughput, spartan, 3a, gigabit, soft, mac, Spartan, Spartan-3a

The packet transmission seems to be all right at 100 Mbps, but I see packets drop at 1000 Mbps, thereby reducing the throughput.


A DCM must be used with Spartan-3A devices to meet the GMII input setup and hold specifications. The phase shift of the DCM required is specific to the FPGA and board and should be changed appropriately.

For further details regarding clocking for the LogiCORE Tri-Mode Ethernet MAC soft IP, see the LogicCORE Tri-Mode Ethernet MAC User Guide (UG138), which is installed with ISE and CORE Generator, and is placed in the "doc" folder when you generate this core with CORE Generator.

Alternatively, you can download the user guide from the lounge. The lounge entrance is located at:

Additionally, it was observed in some cases that the clock resources did not use a BUFGMUX. This could result in timing issues and dropped packets.

A patch has been provided with this Answer Record which has the BUFGMUX instantiated in the clocking logic.

1. Download the patch from:


2. Copy the xps_ll_temac_v1_01_b pcore from the install folder to the <project>\pcores

3. Extract the archive to <project>\pcores\ and over-write with the files in this archive.

4. Clean the generated files and re-implement the design.

A design targeting the Spartan-3A DSP starter kit can be downloaded from:


This design delivers a performance of 40 Mbps running LwIP v3.00.a in raw mode.

The design was created in EDK 10.1.03i. It is supported as-is and might not be upgraded to later versions of the software.

AR# 32096
Date 03/24/2009
Status Active
Type General Article