12-09-2009 01:48 AM
I would like to overclock a Aurora CLK. This use case is described in the section "Clocking using GREFCLK" in the "Virtex-5 FPGA RocketIO GTP Transceiver" ( ug196.pdf ) page 80.
It seems that I have a Xilinx bug or equivalent. When i connect my clk_p and clk_n to an IBUFDS component or an IBUFGDS component which is connected to a DCM, an error message occurs during the mapping.
Pack:1107 - Unable to combine the following symbols into a single IOB
PAD symbol "xmc_312m5_clk_p" (Pad Signal = xmc_312m5_clk_p)
DIFFAMP symbol "i_0/IBUFDS" (Output Signal = xmc_312m5_clk)
An IO component of type IOB was chosen because the IO contains symbols and/or
properties consistent with input, output, or bi-directional usage and
contains no other symbols or properties that require a more specific IO
Each of the following constraints specifies an illegal physical site for a
component of type IOB:
Symbol "xmc_312m5_clk_p" (LOC=AF4 [Physical Site Type = IPAD])
The component type is determined by the types of logic and the properties and
configuration of the logic it contains. Please double check that the types of
logic elements and all of their relevant properties and configuration options
are compatible with the physical site type of the constraint.
Please correct the constraints accordingly.
The bitstream is built without error if I delete the DCM component.
Do you know a solution for this problem ?
12-09-2009 07:34 AM
There isn't a lot go on from your post.
Which software version?
What is connected to the output of the IBUFDS when you are using the DCM and when you aren't?
12-10-2009 12:32 AM
1. Which software version? ISE 10.1.02
2. Which device/package? Virtex 5 sx95t / ff1136
3. What is connected to the output of the IBUFDS when you are using the DCM and when you aren't?
The GTP_DUAL is connected to the output of the IBUFDS when I am not using the DCM.
The DCM is connected to the output of the IBUFDS when I am using the DCM.
It seems that I must not use the DCM to multiply the clock but I must use the PLL included in the GTP_DUAL. I will study this solution.
Nevertheless. I am interresed by an explanation about ERROR:PACK:1107.
12-10-2009 10:19 AM
The simple answer is you can't do that.
The MGTREFCLK locations (MGT118 AF4/AF3 in your example) can only be connected to the GTP_DUAL CLKIN. When you tried to connected it to something else (DCM) the tools generated an error. The error message should be better worded.
You can use the REFCLKOUT or the TXOUTCLK ports to drive your DCM.