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YosysHQ / picorv32

PicoRV32 - A Size-Optimized RISC-V CPU
ISC License
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wbm_sel_o == 0 during read transactions #246

Open epsilon537 opened 9 months ago

epsilon537 commented 9 months ago

The picorv32_wb state machine always sets wbm_sel_o to 0 during Wishbone read transactions:

                if (mem_valid) begin
                    wbm_adr_o <= mem_addr;
                    wbm_dat_o <= mem_wdata;
                    wbm_we_o <= we;
                    wbm_sel_o <= mem_wstrb;

During read transactions mem_wstrb will be 0, so wbm_sel_o gets set to 0. According to the Wishbone spec, sel_o also applies to read transactions, however. Shouldn't wbm_sel_o be set to 4'b1111 during read transactions?