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AR# 29712

9.2i EDK, MPMC v3.00a - Spartan-3 designs generate errors: "NgdBuild:455 mulitple driver" or "NgdBuild:924 input pad net"

Description

Keywords: XST_GND, ilmb_BE, logical, MicroBlaze

When using an MPMC design in a Spartan-3 family device, the following errors occur:

"ERROR:NgdBuild:455 - logical net 'ilmb_LMB_BE<0>' has multiple driver(s):
pin G on block XST_GND with type GND,
pin PAD on block lmb_bram/lmb_bram/ilmb_LMB_BE<0> with type PAD
ERROR:NgdBuild:924 - input pad net 'ilmb_LMB_BE<0>' is driving non-buffer
primitives:
pin G on block XST_GND with type GND,
pin I0 on block
microblaze_0/microblaze_0/Area.Implement_Debug_Logic.Debug_I/dbg_stop_i_not00011 with type LUT3,
pin I0 on block
microblaze_0/microblaze_0/Area.Implement_Debug_Logic.Debug_I/Want_to_Stop_not00011 with type LUT4,
pin I3 on block
microblaze_0/microblaze_0/Area.Implement_Debug_Logic.Debug_I/dbg_stop_i_mux00001 with type LUT4,
pin I1 on block
microblaze_0/microblaze_0/Area.Decode_I/break_Pipe_i_0_or00003_SW0 with type LUT3,
pin I0 on block
microblaze_0/microblaze_0/Area.Using_I_PLB.IPLB_Interface_I1/IPLB_M_request_and00001 with type LUT3,
pin I2 on block
mb_plb/mb_plb/GEN_SHARED.I_PLB_ARBITER_LOGIC/I_ARBCONTROL_SM/Cnt_on_plb2opb_rearb_or00006 with type LUT4,
pin I1 on block
mb_plb/mb_plb/GEN_SHARED.I_PLB_ARBITER_LOGIC/I_ARBCONTROL_SM/Cnt_on_plb2opb_rearb_or00006 with type LUT4,
pin I0 on block ilmb_cntlr/ilmb_cntlr/lmb_we_3_and00001 with type LUT3,
pin I2 on block ilmb_cntlr/ilmb_cntlr/lmb_we_2_and00001 with type LUT3,
pin I2 on block ilmb_cntlr/ilmb_cntlr/lmb_we_1_and00001 with type LUT3,
pin I2 on block ilmb_cntlr/ilmb_cntlr/lmb_we_0_and00001 with type LUT3,
pin I0 on block ilmb_cntlr/ilmb_cntlr/lmb_we_0_and00001 with type LUT3,
pin I0 on block ilmb_cntlr/ilmb_cntlr/lmb_we_1_and00001 with type LUT3,
pin I0 on block ilmb_cntlr/ilmb_cntlr/lmb_we_2_and00001 with type LUT3,
pin I2 on block ilmb_cntlr/ilmb_cntlr/lmb_we_3_and00001 with type LUT3,
pin PRE on block
clock_generator_0/clock_generator_0/clkgen_core_inst/clkgen_arch_inst/using_dcm_arch_model.dcm_array[0].using_dcm_module_inst.dcm_module_inst/rst_delay_2
with type FDP,
pin PRE on block
clock_generator_0/clock_generator_0/clkgen_core_inst/clkgen_arch_inst/using_dcm_arch_model.dcm_array[0].using_dcm_module_inst.dcm_module_inst/rst_delay_1
with type FDP,
pin PRE on block
clock_generator_0/clock_generator_0/clkgen_core_inst/clkgen_arch_inst/using_dcm_arch_model.dcm_array[0].using_dcm_module_inst.dcm_module_inst/rst_delay_0
with type FDP,
pin PRE on block
clock_generator_0/clock_generator_0/clkgen_core_inst/clkgen_arch_inst/using_dcm_arch_model.dcm_array[0].using_dcm_module_inst.dcm_module_inst/rsti with
type FDP"

Solution

Spartan-3 devices require the DDR2_DQS_DIV_I and DDR2_DQS_DIV_O signal externally to create a loopback timing signal. When this signal is not connected, an input to an IBUF inside of the IBUF is tied to internal ground. This situation creates multiple drivers on the ground signal, and an invalid IBUF/PAD connection.

This condition will be flagged by the tools with a more specific error, starting with EDK 10.1 and MPMC v4.00.a.
AR# 29712
Date Created 11/03/2007
Last Updated 01/27/2008
Status Active
Type General Article