Manual fitting with chipplanner

[agaripcan6223]

Hi, I want to generate metastability-based true random numbers using a model where 256 R - S latches are connected in parallel, as in Figure 1. For this, I have to place the NAND gates that make up each R-S latch core in Figure 2 on a different LE on the FPGA (chipplanner). However, the modeled system is optimized by Quartus at the compilation stage and placed on LEs in a stochastic way. Although I tried hard, I could not get a result. I need your knowledge and experience to solve this problem, which is important to me. For this I need to make any adjustments in the Quartus environment or what method should I follow?

I would be very happy if you could help me.

Best regards.

Figure 1. Entropy model

Figure 2. SR latch

[IDeyn]

Hi agaripcan6223 !

In order to create such a design you need to exploit hand placing the LUTs.

Have you tried using Assignments - Location -> LAB combinational cell?

Other issue is to create LUT mask to behave as NAND gate - you need to create hand placed LUTs and change their LUT mask using Resource property editor.

I also need to say that your design is highly unrecommended in FPGAs, here you create clock gating and combinational loops.

--

Best regards,

Ivan

[KhaiChein_Y_Intel]

Hi,

You can prevent optimization by setting the preserve synthesis attribute on the register. You may refer to the syntax below.

Verilog: https://www.intel.com/content/www/us/en/programmable/quartushelp/current/index.htm#hdl/vlog/vlog_file_dir_preserve.htm

VHDL: https://www.intel.com/content/www/us/en/programmable/quartushelp/current/index.htm#hdl/vhdl/vhdl_file_dir_preserve.htm

Thanks.

Best regards,

KhaiY