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VGA IP Core using a dual-port BRAM as a frame buffer

  • This is an example core to show how to access BRAM from both c and vhdl
  • 640x480 Resolution
  • Tested with 14.6 ISE Design Suite
  • Supports hard-coded 4 x 10-byte objects. Check vga_fsl.vhd to change it
  • PORT B of a dual port BRAM is connected as the frame buffer, so that C code in SDK can write through PORTA and VHDL side from the ip reads from PORTB

Using the VGA fsl framebuffer ip core in the EDK project

  • Checkout the project and add it to project repository so that it shows up under peripherals tab in EDK
  • Drag and drop AXI BRAM Controller from IP Catalog to the project
  • From the configuration, under AXI choose AXI4LITE for the AXI4 Protocol option, and check Slave Single Port BRAM option, then hit OK
  • Hit Hardware -> Configure Coprocessor
  • vga_fsl should show up under Available Coprocessors. Hit it and hit << Add then hit Ok
  • Under Bus Interfaces tab expand both the newly generated axi_bram_block and vga_fsl_0 and connect PORTB's together
  • Go to Ports tab and expand vga_fsl_0 choose hsync, vsync, and rgb, right click and hit Make External
  • Generate a 25 MHz clock from clock_generator, and hook it up to vga_clk port
  • If it doesn't automatically, connect FSL_Clk to the bus clock, and SYS_Rst to the bus reset under microblaze_to_vga_fsl_0
  • Check Defaults under Port Filters on the right, and under Ports tab expand the axi_bram_block and connect BRAM_Clk_B to the bus clock
  • Add the external pins to the ucf file. Following is for Digilent Nexys3 board:
## VGA Pins for Digilent Nexys3 Board
NET vga_fsl_0_rgb_pin<7> LOC = "N7"  |  IOSTANDARD = "LVCMOS33"; # RED 2
NET vga_fsl_0_rgb_pin<6> LOC = "V7"  |  IOSTANDARD = "LVCMOS33"; # RED 1
NET vga_fsl_0_rgb_pin<5> LOC = "U7"  |  IOSTANDARD = "LVCMOS33"; # RED 0
NET vga_fsl_0_rgb_pin<4> LOC = "V6"  |  IOSTANDARD = "LVCMOS33"; # GREEN 2
NET vga_fsl_0_rgb_pin<3> LOC = "T6"  |  IOSTANDARD = "LVCMOS33"; # GREEN 1
NET vga_fsl_0_rgb_pin<2> LOC = "P8"  |  IOSTANDARD = "LVCMOS33"; # GREEN 0
NET vga_fsl_0_rgb_pin<1> LOC = "T7"  |  IOSTANDARD = "LVCMOS33"; # BLUE 1
NET vga_fsl_0_rgb_pin<0> LOC = "R7"  |  IOSTANDARD = "LVCMOS33"; # BLUE 0
NET vga_fsl_0_hsync_pin  LOC = "N6"  |  IOSTANDARD = "LVCMOS33"; # HSYNC
NET vga_fsl_0_vsync_pin  LOC = "P7"  |  IOSTANDARD = "LVCMOS33"; # VSYNC
  • Generate bitstream and you should see the stuff in the bram on your monitor. (Well partial, and well black by default probably)
  • Head into SDK to write some stuff to the BRAM to display it

Examples

  • Check out examples/framebufferdemo.c to see an example on how to write to BRAM from SDK
  • Check out examples/system.mhs to see an example design
  • Download examples/nexys3_vga_fsl_shared_bram_demo.bit to your Nexys3 board for the demo that displays bram content on the monitor connected through VGA