Stats

  • Locked Locked
  • Replies 2
  • Subscribers 65
  • Views 18117
  • Members are here 0
This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

$xm_deposit in gate level simulation

mxm1489

Hello,

i tried to deposit a value inside a register using this code:

$xm_deposit("tb_chip_top_s222.dut_u.i_digtoppad.i_dig_top_pads.i_dig_top.i_volt_cfg_regs.i_cfg_3_secded.\\secded_data_r_reg[0] .Q", $sformatf("%b", cfg_3_secded_register_value[0]));

This works in rtl simulation but i have some issues in gate level simulation where the deposit seems to behave like a force ( i see the D signal of the flip flop equal to 1 but it is not sampled after the posedge of the clock, maybe beacuse of the deposit on Q)

Any suggestions?

Thanks

  • In the RTL sim, the internal state of the register is the same signal as the output of the register. So the deposit is overridden when the internal state is updated. Often in a synthesized model, the internal state of a flop is separated by one or more signals from the register's output. (The internal state may be a sequential UDP's "reg" variable.) Unless the deposit is changed to reference that internal signal, there can be times when the internal state change will not propagate to override the downstream deposit.

    In version 17.10 of the simulator and later, there is an option -deposit_value_change which may override this behavior in your simulation. Give that a try and see if it works. If not, file a ticket with support.cadence.com and let them see how your gate-level register is modeled. The support AE's will be able to figure out what is happening.

  • in reply to TAM1

    Thanks for the response,

    It does not seems to work..I will open a ticket as suggested.

    Regards,

    Max

Community Guidelines

The Cadence Design Communities support Cadence users and technologists interacting to exchange ideas, news, technical information, and best practices to solve problems and get the most from Cadence technology. The community is open to everyone, and to provide the most value, we require participants to follow our Community Guidelines that facilitate a quality exchange of ideas and information. By accessing, contributing, using or downloading any materials from the site, you agree to be bound by the full Community Guidelines.