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AR# 36370

12.1 Place - ERROR:Place:1158 - Unroutable Placement! A BUFIO / DCM clock component pair have been found that are not placed at a routable BUFIO / DCM site pair.

Description


When I try to connect a BUFIO2 to a DCM or a PLL, the tool reports an error similar to the following:

ERROR:Place:1158 - Unroutable Placement! A BUFIO / DCM clock component pair have been found that are not placed at a
   routable BUFIO / DCM site pair. The BUFIO component <gtpclkout0_0_dcm0_bufio2_i> is placed at site <BUFIO2_X2Y28>.
   The corresponding DCM component <gtpclkout0_0_dcm0_i/clock_divider_i> is placed at site <DCM_X0Y1>. The BUFIO can use
   the fast path between the BUFIO and the DCM if the BUFIO is in TOPor BOTTOM edge and both the BUFIO & DCM are placed
   in the same half of the device (TOP or BOTTOM). This placement is UNROUTABLE in PAR and therefore, this error
   condition should be fixed in your design. You may use the CLOCK_DEDICATED_ROUTE constraint in the .ucf file to demote
   this message to a WARNING in order to generate an NCD file. This NCD file can then be used in FPGA Editor to debug
   the problem. A list of all the COMP.PINS used in this clock placement rule is listed below. These examples can be
   used directly in the .ucf file to demote this ERROR to a WARNING.
   < PIN "gtpclkout0_0_dcm0_bufio2_i.DIVCLK" CLOCK_DEDICATED_ROUTE = FALSE; >
   < PIN "gtpclkout0_0_dcm0_i/clock_divider_i.CLKIN" CLOCK_DEDICATED_ROUTE = FALSE; >



Why does the software report this error?

How can I resolve this issue?

Solution


In a Spartan-6 device, a BUFIO2 driving a DCM must be located in the same half as the DCM.

For example if the BUFIO2 is in the top half, then the DCM must also be in the top half.

This error is reported when the BUFIO2 and DCM are not located in the same half of the silicon.

You can use FPGA Editor to determine whether or not the BUFIO2 & DCM pair are placed in the same half.

To resolve this issue, you must put the BUFIO2/DCM pair in the same half.

If there are no available DCMs in the top or bottom half then PLLs in that half can be used instead.
AR# 36370
Date Created 06/23/2010
Last Updated 09/24/2014
Status Active
Type General Article
Devices
  • Spartan-6 LX