Use of BRAM in ICE40 ...

Question

Use of BRAM in ICE40 ...

PPlinux opened this issue 3 years ago · 2 comments

Dear,

can anyone help me using BRAM 512 word, 16 bit as a ROM (RAM preloaded during FPGA power on)
using GHDL VHDL -> Yosys -> Lattice ICE40 FPGA please ?

Greetings,

Patrick

Answer 1 · 2022-07-21T10:05:16.000Z

I am new to the toolchain and am having trouble understanding how the techmap works in the plugin.

I have two entities, one is designed to be ROM while another as RAM.
The ROM was mapped to BRAM while the RAM to DFFs.

I have no idea how to change this. Can anyone give some hints?

Thanks in advance.

Answer 2 · 2022-07-22T17:30:15.000Z

There is no ROM in an fpga, so it is expected that a ROM is mapped to a BRAM. If you RAM is not correctly described as a RAM, the synthesizer will use DFFs to implement it.