Invalid constraint on register 'IO0_I_REG' during implementation

[musthafavakeri]

Hi All,

Tool : Vivado 15.2.1

Device : xc7vx485tffg1761-2

Error: 

1) [Place 30-73] Invalid constraint on register 'IO0_I_REG'. It has the property IOB=TRUE, but it is not driving or driven by any IO    element.

2) [Place 30-73] Invalid constraint on register      'RATIO_NOT_EQUAL_4_GENERATE.SCK_O_NQ_4_NO_STARTUP_USED.SCK_O_NE_4_FDRE_INST'. It has the property IOB=TRUE,    but it is not driving or driven by any IO element.

I got these errors during implementation. But when I click at the blue lines, it says " cannot find cell".

Why does this happen......? 

Thanks ,

Musthafa

[vemulad]

Hi @musthafavakeri

Can you attach _opt.dcp located in .runs-->impl_1 folder?

Also right click in messages window and select "discard old messages" in case if these messages are from old runs this helps.

Thanks,

Deepika.

[musthafavakeri]

Hi Deepika,

Thank you for your reply.

Please find attached the _opt.dcp file.

Thanks,

Musthafa 

[vemulad · Accepted solution]

Hi @musthafavakeri

Open Implemented design and use the below commands to report the cells mentioned in the warning message.

show_objects -name find_1 [get_cells -hierarchical -filter { NAME =~ "*IO0_I_REG*" } ]
show_objects -name find_2 [get_cells -hierarchical -filter { NAME =~ "*RATIO_NOT_EQUAL_4_GENERATE.SCK_O_NQ_4_NO_STARTUP_USED.SCK_O_NE_4_FDRE_INST*" } ]

1) [Place 30-73] Invalid constraint on register 'IO0_I_REG'. It has the property IOB=TRUE, but it is not driving or driven by any IO    element.

2) [Place 30-73] Invalid constraint on register      'RATIO_NOT_EQUAL_4_GENERATE.SCK_O_NQ_4_NO_STARTUP_USED.SCK_O_NE_4_FDRE_INST'. It has the property IOB=TRUE,    but it is not driving or driven by any IO element.

The second warning message is correct. The flop mentined in second warning has IOB property set to TRUE (you can check cell properties window) and it is not eligible for packing in to IOB as it is not connected to top level ports directly.

The first warning message seems to be incorrect as the cells which I found using the below command are indeed placed in IOB. I will check this further.

show_objects -name find_1 [get_cells -hierarchical -filter { NAME =~ "*IO0_I_REG*" } ]

Thanks,

Deepika.

[vemulad]

Hi @musthafavakeri

The first warning talks about instance "mblaze_wrapper_inst/mblaze_i/axi_quad_spi_1/U0/IO0_I_REG".

show_objects -name find_3 [get_cells -hierarchical -filter { NAME =~ "*mblaze_wrapper_inst/mblaze_i/axi_quad_spi_1/U0/IO0_I_REG*" } ]

This flop cannot be packed in to IOB as it is not connected to top level ports.

Thanks,

Deepika,

[vemulad]

Hi @musthafavakeri

I have filed CR 910931 and addressed the below issues to factory

1. The first warning message has to list the complete hierarchical name of the instance.

2. The hypderlinks in the message window have to be fixed.

Thanks,

Deepika.

[musthafavakeri]

Hi Deepika,

I am very thankful to you. It worked. You explained it very well.

Thanks,

Musthafa

[arhoufiry]

Can you please confirm what the solution is?

Did you just set the IOB property to FALSE?