Format

Xilinx data2mem

1. Create a BMM file named "uc.bmm" for inclusion in the build process:
   
   The file should look like the following. The text "top_inst/uc_inst" needs to be modified to point to your instantiation of the micro controller. Sometimes "uc_inst/Mram_s_opcodeMemory" becomes "uc_inst_Mram_s_opcodeMemory"
   
   ADDRESS_SPACE uc RAMB18 WORD_ADDRESSING [0x0:0x7FF]
     BUS_BLOCK
       top_inst/uc_inst/Mram_s_opcodeMemory [0:8];
     END_BUS_BLOCK;
   END_ADDRESS_SPACE;
   
   The following command can be used to verify the syntax of this BMM file:
   
     data2mem -bm uc_bmm
   
   WARNING: Using "ARCHITECTURE 4096" on a Spartan-6 build produced two RAMB16's and one RAMB8, not the expected two RAMB18's. Changing the configuration command to "ARCHITECTURE 2048*2" produced the desired results. The following BMM extracted the two RAMB18 locations with the desired memory mapping:
   
   ADDRESS_SPACE uc RAMB18 WORD_ADDRESSING [0x0:0xFFF]
     BUS_BLOCK
       top_inst/uc_inst_Mram_s_opcodeMemory_0 [0:8];
     END_BUS_BLOCK;
     BUS_BLOCK
       top_inst/uc_inst_Mram_s_opcodeMemory_1 [0:8];
     END_BUS_BLOCK;
   END_ADDRESS_SPACE;
   
   Note: For a Spartan-3A the bit indices [0:8] may need to be reversed.
   
   
2. Add this file to the build process.
   
   For a command-line build this is done by adding "-bm uc.bmm" to the argument list for ngdbuild.
   
   When bitgen is run it will create a file named "uc_bd.bmm which will include the memory block address required to run data2mem.
   
   
3. Perform the build and ensure that uc_bd.bmm has the address for the memory block.
   
   
4. Run data2mem as follows, where "orig.bit" is the assumed name for the original bitstream generated by Xilinx' tools:
   
   data2mem -bm uc_bd.bmm -bt orig.bit -bd uc.mem -o b new.bit;
   
   
5. Compare the original bitstream to the modified bitstream as follows to ensure this process worked.
   
   data2mem -bm uc.bmm -bt orig.bit -d > orig.dump;
   data2mem -bm uc.bmm -bt new.bit -d > new.dump;
   diff orig.dump new.dump | less;
   
   The only differences other than file names and dates and such should be the initialization values for the memory block.
   
   You can validate this process by using the original memory initialization file, in which case the above differences should be limited to the file name, data, etc., but not the memory contents.
   
   

Xilinx Vivado

1. Determine the name of the memory.
   
   The following commands lists the names of all the block rams. This obviously needs to be done after place and route.
   
   join [get_cells -hierarchical -filter { LOC =~ "RAMB*" }] "\n";
   
   or
   
   join [filter [get_cells -hierarchical] { BEL =~ "RAMB*" }] "\n"
   
   Alternatively, the following command lists the names of the block rams, the type of the block ram, and their locations:
   
   foreach a [filter [get_cells -hierarchical] { BEL =~ "RAMB*" }] { puts "$a [lindex [report_property -return_string $a BEL] 7] [lindex [report_property -return_string $a LOC] 7]"; }
   
   Any of these can be included in the build script or can be cut and pasted into the TCL console in the GUI after place and route.
   
   Note: The "list_property_value" seems to be more natural to use than the "[lindex ..." commands, but can only be used for enumerated types, i.e., not for BEL and LOC properties.
   
   
2. Once you've identified the name(s) of the memories, add the following command to the build script or use it on a checkpoint. Here, uc/inst/s_PC_reg_rep was the single memory in the micro controller.
   
   foreach memName [list "uc/inst/s_PC_reg_rep"] {
     set memBel [lindex [report_property -return_string [get_cells $memName] BEL] 7];
     set memLoc [lindex [report_property -return_string [get_cells $memName] LOC] 7];
     puts "MYBMMINFO: $memName $memBel $memLoc]";
   }
   
   This should add lines starting with "MYBMMINFO:" to the Vivado log file with each memory name, type, and location.
   
   Note: If the processor uses more than one block ram, simply append the name to the "list" in this TCL script.
   
   
3. Use the following gawk script or similar to generate a BMM file from the "MYBMMINFO:" lines. Here, the "vivado.log" is the Vivado log file and "build-bmm is the name of this file.
   
   #!/bin/bash
   #
   # Generate a BMM file for the micro controller from the MYBMMINFO lines in the
   # Vivado log file.
   #
   # Usage:  ./build-bmm
   
   gawk -- '
   BEGIN {
     nMemories = 0;
     memName[nMemories++] = "uc/inst/s_PC_reg_rep";
   }
   /^MYBMMINFO:/ { bel[$2] = $3; loc[$2] = $4; }
   END {
     for (ix=0; ix<nMemories; ++ix)
       if (!(memName[ix] in bel)) {
         printf("FATAL ERROR:  MYBMMINFO record not found for \"%s\"\n", memName) > "/dev/stderr";
         exit 1;
       }
     memType = "";
     for (ix=0; ix<nMemories; ++ix) {
       split(loc[memName[ix]],splitLoc,"_");
       if (memType == "") {
         memType = splitLoc[1];
         if (memType = "RAMB18") L = 2048;
         if (memType = "RAMB36") L = 4096;
         L *= nMemories;
         printf("ADDRESS_SPACE uc %s WORD_ADDRESSING [0x0:0x%x]\n",memType,L-1);
       }
       else if (splitLoc[1] != memType) {
         printf("Inconsistent memory types:  %s is %s instead of %s\n",memName[ix],splitLoc[1],memType) > "/dev/stderr";
         exit 1;
       }
       printf("  BUS_BLOCK\n");
       printf("    %s [8:0] PLACED = %s;\n",memName[ix],splitLoc[2]);
       printf("  END_BUS_BLOCK;\n");
     }
     printf("END_ADDRESS_SPACE;\n");
   }
   ' vivado.log > build_uc.bmm
   
   
4. Update the contents of the bitstream file as follows. Here, build.bit is the original bitstream and build_uc.bit is the bitstream updated with the new micro controller instructions.
   
   data2mem -bm build_uc.bmm -bt build.bit -bd uc/uc.mem -o b build_uc.bit
   
   Alternatively, use something like the following as an "update_uc" script file:
   
   #!/bin/bash
   #
   # Update the micro controller instruction memory in the BIT file.
   #
   # Usage:  ./update-uc
   
   if test ! -f build_uc.bmm -o vivado.log -nt build_uc.bmm; then
     ./build-bmm || { echo "build-bmm failed" > /dev/stderr; exit 1; }
   fi
   
   ( cd uc; ssbcc -q --define-clog2 uc.9x8 ) \
   || { echo "ssbcc failed" > /dev/stderr; exit 1; }
   
   data2mem -bm build_uc.bmm -bt build.bit -bd uc/uc.mem -o b build_uc.bit \
   || { echo "data2mem failed" > /dev/stderr; exit 1; }