Trying to configure correctly the display HyperPixel 4.0 Square Touch on FreeBSD 14.2 for Raspberry Pi Zero 2W

[ZioMario]

Hello to everyone.

I'm trying to configure the display hyperpixel 4.0 Square Touch that I've bought here :

https://shop.pimoroni.com/products/hyperpixel-4-square?variant=30138251477075

with FreeBSD 14.2 that I have installed on the Raspberry Pi Zero 2W. I've used these parameters inside the config.txt file :

overscan_left=0
overscan_right=0
overscan_top=0
overscan_bottom=0
framebuffer_width=720
enable_dpi_lcd=1
display_default_lcd=1
dpi_group=2
dpi_mode=87
dpi_output_format=0x5f026
dpi_timings=720 0 20 20 40 720 0 15 15 15 0 0 0 60 0 36720000 4

I'm using the 40 pins of the GPIO connector :



Some parameter is not correct because the display does not turn on. While it works correctly with Linux for the raspberry pi :




Someone has bought this display and can give some suggestions ? thanks

 

[kpedersen]

Not used that specific device (maybe the chip, not sure...).

The best thing is always refer to the datasheet. You can see from the SDA / SCL pins that this is using the i2c protocol. Likely for the touch information. I would use something like i2cdetect (or write your own to poll all channels, similar to scan.c) to make sure things are working first.

Check out the libgpio(3) manpage. Nice and easy API in FreeBSD base. It does not expose hardware i2c but it is trivial to write the ~3 wiringpi wrapper functions for a software i2c implementation.

Since you are working on a Phone(?) for FreeBSD. I would possibly not even bother hooking up these touch events to X11/Wayland. Instead just an SDL3 (or even libdrm) program that covers all aspects of the phone functionality.

 

[Phishfry]

I am curious how the display shows up under amd64 machine? HDMI works?

I have never had to add anything in config.txt for HDMI monitor to work. I don't use RPi much but I would expect it to just work.

Have you tried without any config.txt settings?

For the touch screen on Arm use sysutils/i2c-tools to see if the the address shows up on the bus. You will need to create a Device Tree Overlay or config.txt entry for i2c.

 

[ZioMario]

It is not HDMI. I have attached my HDMI monitor to the raspberry together with the hyperpixel 4.0 Square Touch,with the idea to be able to make some experiments,but my HDMI monitor does not turn on if the hyperpixel 4.0 Square Touch is attached to the pins. I think I should configure the raspberry pi zero in headless mode,to work on it using SSH and the konsole.

 

[Phishfry]

OK i looked at the specs and it is not HDMI but DPI. A variant of SPI.
Question: Do we support DPI?
We do support different speeds of SPI but I dunno about this DPI.
Is it just 1000khz i2c?

spi(8)

man.freebsd.org

I can't find any useable information from the various links on the PiMoroni site for the product.
The device uses all 40 pins and will not work on FreeBSD easily. They need to worry less about reviews and post instructions for other OS.

 

[Phishfry]

Look at this github:

GitHub - pimoroni/hyperpixel4: Driver for the Pimoroni HyperPixel 4.0" Touchscreen Display

Driver for the Pimoroni HyperPixel 4.0" Touchscreen Display - pimoroni/hyperpixel4

github.com

That is the driver? Where? They speak of an Deskop Overlay but where is it?????

Looking there it is calling it an DSI monitor?

Section "Monitor"
    Identifier "DSI-1"
    Option "Rotate" "left"

Then look here:

run make to build a new hyperpixel4.dtbo

So you need to download the source for thier OS and look at the DTS files provided for clues.

 

[Phishfry]

Here they seem to indicate that DPI is SPI like but using more pins.

https://www.reddit.com/r/RetroPie/comments/11qlyur/dpi_vs_spi_vs_dsi_screens/?rdt=47581

So you would need to add support to FreeBSD for DPI. I doubt an overlay would be enough.

 

[Phishfry]

OK I was missing the individual pages for each monitor.

hyperpixel4/src at square-pi4-2021 · pimoroni/hyperpixel4

Driver for the Pimoroni HyperPixel 4.0" Touchscreen Display - pimoroni/hyperpixel4

github.com

So you have a c-init and dts. That could get you somewhere.

Most of the config is in here:

hyperpixel4/src/hyperpixel4-init.c at square-pi4-2021 · pimoroni/hyperpixel4

Driver for the Pimoroni HyperPixel 4.0" Touchscreen Display - pimoroni/hyperpixel4

github.com

It would have to be smoothed for FreeBSD use. Particularly the GPIO Pin assignments. You might need to callup libgpio.
I see it uses 4 Pins here so that might be possible.

 

[Phishfry]

So lets start with this simple thing. You must enable SPI. This gives you an idea of the pins. These are standard Pi SPI pins. So enable SPI via config.txt. I don't see it enabled.

These are Clock, MOSI and CS pins:
#define CLK RPI_V2_GPIO_P1_13 // BCM 27
#define MOSI RPI_V2_GPIO_P1_37 // BCM 26
#define CS RPI_V2_GPIO_P1_12 // BCM 18
#define DELAY 100 // clock pulse time in microseconds
#define WAIT 120 // wait time in milliseconds

#define PIN RPI_V2_GPIO_P1_35
So figure out what this does and you may need to reserve it with an overlay. Maybe the backlight.

 

[Phishfry]

The settings here seem like what you need on FreeBSD to enable SPI Bus.

FreeBSD on the Pi Zero 2 W

Hi, Trying to run any version of freebsd on the zero 2w. I believe the earlier generation pi zero could run FreeBSD as well as other Pis.

forum.core-electronics.com.au

Quoting:
With a config.txt:

[all]
arm_64bit=1
dtparam=audio=on,i2c_arm=on,spi=on
dtoverlay=mmc
dtoverlay=disable-bt
device_tree_address=0x4000
kernel=u-boot.bin
hdmi_safe=1

The key parameters:
dtparam=i2c_arm=on,spi=on

 

[Phishfry]

There are two SPI buses on the RPiZero2. SPI0 and SPI1.

SPI at Raspberry Pi GPIO Pinout

Raspberry Pi SPI pins

pinout.xyz

Notice here the additional help. It shows how to enable only a single bus. That may be needed if using other pins muxed.

You want to check your monitors pins to that chart. See what SPI bus you need to be using. (Hint SPI0)