Openroad doesn’t keep track of scan chain configurations in the ODB.

Once a scan chain has been backed in, nothing tells you a scan chain has been inserted.

One way of checking available scan chains is though the def files.

set def_file [make_result_file tes.out.def]
write_def $def_file

To know if a scan chain is present, check for the presence of the SCANCHAINS lable, eg :

SCANCHAINS 1 ;

Openroad

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Get name of net connected to Q on an sdff instance

openroad> get_name [[$inst find_pin Q] net]
m_bsc_result_out.g_bsp_inner[3].m_inner.ff_2_q

Get instance of cell by name:

openroad> get_cells _4170_
_40c85b0fc4550000_p_Instance

Dont touch commint back to bite me

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When trying to automatically connect

WARNING: [Netlist 29-48] Cannot modify dont-touch net 'm_top/m_bsc_result_out/g_bsp_inner[5].m_inner/ff_2_q'.
ERROR: [Coretcl 2-1653] could not connect net 'm_top/m_bsc_result_out/g_bsp_inner[5].m_inner/ff_2_q' to requested pins.
ERROR: [Common 17-39] 'connect_net' failed due to earlier errors.

Not done yet

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After believing the insertion was sucessfull I am greeted to this opt_design failture … so sad

opt_design failed
ERROR: [Opt 31-67] Problem: A LUT3 cell in the design is missing a connection on input pin I0, which is used by the LUT equation. This pin has either been left unconnected in the design or the connection was removed due to the trimming of unused logic. The LUT cell name is: m_top/m_bsc_result_out/g_bsp_inner[4].m_inner/ff_1_q_reg_scanmux/res_o_INST_0.

Getting the scan chain

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As the scan chain doesn’t apprear in the original HDL code, and the order of the scan flops in the chain is implementation defined, we must extract the scan chain topology from the implementation results.

Renamping to flops

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We obtained the chain ordered by scan dff cells, the next step is to remap these abstract cell names to the