Data Sheet

ManualsBrands4D Systems ManualsRaspberry Pi Accessories / HATs3.5" Primary Display for Raspberry Pi A+/B+/2

4D SYSTEMS 4DPi-35 Primary Display – Raspberry Pi Compatible

4DPi

-35

Primary Display

– Raspberry Pi

7) Run the following command

sudo nano /etc/X11/xorg.conf.d/99-

calibration.conf

Copy the information shown in step 4 into this

file, save it and exit nano.

8) Restart your Raspberry Pi. You should now

have a perfectly calibrated 4DPi-35.

Change the Display Orientation

To change the display orientation, simply edit the

/boot/cmdline.txt file

Find the parameter:

4dpi.rotate = 0

And change this to have the value of 0, 90, 180 or

270.

Save the file and restart your Raspberry Pi.

The touch screen with automatically remap the

alignment thanks to the custom kernel.

Change the SPI Freq and Compression

The 4DPi-35 can be adjusted to work with a range

of SPI Frequencies and levels of compression,

depending on the requirements of the end

product/project.

Increasing the frequency can result in a higher

Frame Rate (FPS), however will use more power

and processor time.

Increasing the level of the compression can also

result in a higher FPS, but may cause the display to

corrupt.

By default, a SPI Frequency of 48Mhz is used, with

a Compression level of 7.

The following parameters are the defaults in the

/boot/cmdline.txt file, and can be edited to adjust

the Frequency and Compression level.

4dpi.sclk=48000000

4dpi.compress=7

Setting compress to be 1 will enable the kernel to

control the level of compression based on the

frequency selected. This however is not

guaranteed to have a good end result, and may

require manually setting the compression level if

corruption on the display is experienced.

If corruption or display anomalies occur at any

given compression level, try to lower it by 1 value

and check if this has improved.

Note, changing the frequency and compression

require a restart of the Raspberry Pi.

Please refer to Section 4.7 for more information

Backlight Control

The backlight is controllable in two possible ways.

One is using simple on/off control, which is

controllable by sending a SPI command to the on-

board processor, which then turns the backlight on

and off. The other is using a PWM output from the

Raspberry PI and controlling the backlight

brightness.

The control of the backlight is selected using the

Jumper J1, but selecting either ON/OFF or PWM

control.

By default, the Kernel has enabled PWM control,

which is controlled off the GPIO18 pin from the

Raspberry Pi. This can be enabled or disabled by

adding a line in the /boot/cmdline.txt file:

Adding this will disable the PWM and free GPIO18:

4dpi.pwm=0

Adding this will enable the PWM:

4dpi.pwm=1

To control the backlight using ON/OFF control,

ensure the cmdline.txt file has been edited

appropriately (and restart the Pi), place the jumper

in the ON/OFF position and executing the

following commands will control the backlight:

To turn the backlight off:

sudo echo 0 > /sys/class/backlight/4dpi-35-

pwm/brightness

To turn the backlight on:

sudo echo 1 > /sys/class/backlight/4dpi-35-

pwm/brightness

To control the backlight using PWM control,

ensure the cmdline.txt file has been edited

appropriately (and restart the Pi), and place the

jumper in the PWM position.

Executing the following commands will set the

backlight brightness: