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Device Tree
Raspberry Pi see also: FBTFT-RPI-overlays
Most displays need GPIOs for signaling. These are common for SPI and parallel:
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reset-gpios
Hardware reset -
dc-gpios
Data/Command (sometimes called RS) -
led-gpios
Backlight
Parallel bus displays:
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db-gpios
Databus gpios -
cs-gpios
Chip Select -
wr-gpios
Write strobe
Other properties:
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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>;
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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
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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