Device Tree

Raspberry Pi see also: FBTFT-RPI-overlays

Supported properties

Most displays need GPIOs for signaling. These are common for SPI and parallel:

• reset-gpios
  Hardware reset
• dc-gpios
  Data/Command (sometimes called RS)
• led-gpios
  Backlight

Parallel bus displays:

• db-gpios
  Databus gpios
• cs-gpios
  Chip Select
• wr-gpios
  Write strobe

Other properties:

• rotate
  Angle to rotate display counter clockwise: 0, 90, 180, 270

• bgr
  Set/clear BGR bit (supported by some drivers). Use if Red and Blue is swapped.

• init
  Overrides the default init sequence.
  Init sequence markers values are OR'ed with the actual value: 0x1000000: command, 0x2000000: millisecond delay Example:

    init = <0x10000b0 00
    	0x1000011
    	0x20000ff
    	0x10000b3 0x02 0x00 0x00 0x00
    	0x10000c0 0x13 0x3b 0x00 0x02 0x00 0x01 0x00 0x43
    	0x10000c1 0x08 0x16 0x08 0x08
    	0x10000c4 0x11 0x07 0x03 0x03
    	0x10000c6 0x00
    	0x10000c8 0x03 0x03 0x13 0x5c 0x03 0x07 0x14 0x08 0x00 0x21 0x08 0x14 0x07 0x53 0x0c 0x13 0x03 0x03 0x21 0x00
    	0x1000035 0x00
    	0x1000036 0xa0
    	0x100003a 0x55
    	0x1000044 0x00 0x01
    	0x10000d0 0x07 0x07 0x1d 0x03
    	0x10000d1 0x03 0x30 0x10
    	0x10000d2 0x03 0x14 0x04
    	0x1000029
    	0x100002c>;
  

• width
  Display width in pixels

• height
  Display height in pixels

• fps
  Frames per second (default 20)
  In effect this states how long the driver will wait after video memory has been changed until display update transfer is started.
  See Debug for a way to show how long the actual transfer takes.
  More info

• gamma
  String representation of Gamma Curve(s). Driver specific. Not supported by all drivers.
  Mode info

• txbuflen
  Length of the FBTFT transmit buffer.
  This buffer is used by default on Little Endian architectures like on the Raspberry Pi. The 2 bytes in the 16-bit pixel value has to be swapped before transfer.
  It is also used when other transformation has to be done.
  When FBTFT is compiled on Little Endian, it uses a default buffer of 4096 bytes. txbuflen can be used to change this.
  txbuflen has some special values:

  • -1 makes the buffer the same size as video memory.
  • -2 forces no buffering

• startbyte
  Sets the Start byte used by some SPI displays. Usually 0x70 (01110000) or 0x74 (01110100).
  Format: 5 bit magic + 1 bit id + 1 bit RS + 1 bit RW. RS and RW is set by FBTFT.

• buswidth
  Display bus interface width

• regwidth
  Display controller register width

• bpp
  Bit per pixel

• debug
  Debug output to kernel log