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FrameBufferIP Handbook

FrameBufferIP Handbook

Owned by Wojciech Kloska
Dec 02, 2024
2 min read

Description

FrameBuffer controller with built-in configurable buffer.

Block Diagram

 

1614698524121-156-20241202-162937.png

 

Register Map

ID 0x0 RO         FrameBuffer ID register     [31: 0] ID Always returns 0xdead2137
ENABLE 0x04 RW         FrameBuffer enable register - controls functionalities of the IP     [31: 2] RSVD_0     [ 1: 1] REFRESH Enables fetching from external memory     [ 0: 0] ENABLE Global controller enable bit
MODE 0x08 RW         Mode control register     [31:24] SOLID_BLUE     [23:16] SOLID_GREEN     [15: 8] SOLID_RED     [ 7: 2] RSVD_0     [ 1: 0] MODE 0-BUFFER, 1-TEST_PATTERN, 2-SOLID, 3-WHITE
WRAP 0x0C RW         Buffer wrap control register. Possible use case - tiled background     [31:16] Y_WRAP     [15: 0] X_WRAP
ADDR_LO 0x10 RW         LSb of external memory     [31: 0] ADDR_LO
ADDR_HI 0x14 RW         MSb of external memory     [31: 0] ADDR_HI
RSVD 0x18 RW         Reserved     [31: 0] RSVD
RSVD 0x1C RW         Reserved     [31: 0] RSVD
SYNC_PIXELS 0x20 RW         SYNC pixels     [31:16] VSYNC Vertical SYNC pixels     [16: 0] HSYNC Horizontal SYNC pixels
BACK_PORCH 0x20 RW         Back porch pixels     [31:16] VBACK Vertical back porch pixels     [16: 0] HBACK Horizontal back porch pixels
ACTIVE_PIXELS 0x28 RW         Active pixels     [31:16] VACTIVE Vertical Active pixels     [16: 0] HACTIVE Horizontal Active pixels
FRONT_PORCH 0x2c RW         Front porch pixels     [31:16] VFRONT Vertical front porch pixels     [16: 0] HFRONT Horizontal front porch pixels
POLARITY 0x30 RW         Active pixels     [31:17] RSVD     [16]    VPOL Vertical polarity     [15: 1] RSVD     [0]     HPOL Horizontal polarity

Examples

Tiled background via GDB

 Connect GDB to remote target (see GDB over JTAG) of RCHD-PF and execute following commands:

  1. restore to fill memory buffer in the FrameBuffer with static data that you want to display in RGB565 format (in this example it is 256x64 bitmap)

  2. enable displaying the memory content

  3. adjust memory buffer address wrapping - to match the uploaded bitmap width 

(gdb) restore logo.bin binary 0x60038000 0 0x10000 Restoring binary file logo.bin into memory (0x60038000 to 0x60040000) (gdb) set *((int*)0x60030004)=0x00000003 The riscv_frame_cache's start_addr is 0 (from the get_frame_func). Forcing it to the value of the PC (0x000000002022037a) to avoid the riscv_scan_prologue reading between 0-99 addr esses. The riscv_frame_cache's start_addr is 0 (from the get_frame_func). Forcing it to the value of the PC (0x000000002022037a) to avoid the riscv_scan_prologue reading between 0-99 addr esses. (gdb) set *((int*)0x6003000c)=0x00000080 The riscv_frame_cache's start_addr is 0 (from the get_frame_func). Forcing it to the value of the PC (0x000000002022037a) to avoid the riscv_scan_prologue reading between 0-99 addr esses. (gdb)

After executing all three commands the HDMI output should present the buffer content tiled.