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Update instruction for setting up TD2 on Compute Modules #4084

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May 8, 2025
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Update instruction for setting up TD2 on Compute Modules #4084

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2d237cb
Add information on setting up TD2 on Compute modules
JamesH65 Apr 16, 2025
e16b709
Update for review comments
JamesH65 Apr 29, 2025
bc19de2
review comments from DaveS
JamesH65 Apr 29, 2025
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MOre review fixups
JamesH65 Apr 29, 2025
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4 changes: 4 additions & 0 deletions documentation/asciidoc/accessories/display/display_intro.adoc
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Expand Up @@ -159,3 +159,7 @@ To specify these options, add them, separated by commas, to your `dtoverlay` lin
----
dtoverlay=vc4-kms-dsi-7inch,sizex=400,invx,invy
----

=== Installation on Compute Module based devices.

All Raspberry Pi SBCs auto-detect the official Touch Displays as the circuitry connected to the DSI connector on the Raspberry Pi board is fixed; this autodetection ensures the correct Device Tree entries are passed to the kernel. However, Compute Modules are intended for industrial applications where the integrator can use any and all GPIOs and interfaces for whatever purposes they require. Autodetection is therefore not feasible, and hence is disabled on Compute Module devices. This means that the Device Tree fragments required to set up the display need to be loaded via some other mechanism, which can be either with a dtoverlay entry in config.txt as described above, via a custom base DT file, or if present, a HAT EEPROM.
7 changes: 7 additions & 0 deletions documentation/asciidoc/accessories/touch-display-2/about.adoc
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Expand Up @@ -127,3 +127,10 @@ To specify these options, add them, separated by commas, to your `dtoverlay` lin
----
dtoverlay=vc4-kms-dsi-ili9881-7inch,sizex=400,invx,invy
----

=== Installation and software setup on Compute Module based devices.

All Raspberry Pi SBCs auto-detect the official Touch Displays as the circuitry connected to the DSI connector on the Raspberry Pi board is fixed; this autodetection ensures the correct Device Tree entries are passed to the kernel. However, Compute Modules are intended for industrial applications where the integrator can use any and all GPIOs and interfaces for whatever purposes they require. Autodetection is therefore not feasible, and hence is disabled on Compute Module devices. This means that the Device Tree fragments required to set up the display need to be loaded via some other mechanism, which can be either with a dtoverlay entry in config.txt, via a custom base DT file, or if present, a HAT EEPROM.

Creating a custom base Device tree file is beyond the scope of this documentation, however, it is simple to add an appropriate device tree entry via `config.txt`. See this xref:../computers/compute-module.adoc#attaching-the-touch-display-2-lcd-panel[page] for configuration details.

32 changes: 25 additions & 7 deletions documentation/asciidoc/computers/compute-module/cmio-display.adoc
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@@ -1,16 +1,16 @@
== Attach the official 7-inch display
== Attaching the Touch Display LCD panel

Update your system software and firmware to the latest version before starting.
Compute Modules mostly use the same process, but sometimes physical differences force changes for a particular model.

=== Connect a display to DISP1
=== Connect a display to DISP1/DSI1

NOTE: The Raspberry Pi Zero camera cable cannot be used as an alternative to the RPI-DISPLAY adapter. The two cables have distinct wiring.

To connect a display to DISP1:
To connect a display to DISP1/DSI1:

. Disconnect the Compute Module from power.
. Connect the display to the DISP1 port on the Compute Module IO board through the 22W to 15W display adapter.
. Connect the display to the DISP1/DSI1 port on the Compute Module IO board through the 22W to 15W display adapter.
. _(CM1, CM3, CM3+, and CM4S only)_: Connect the following GPIO pins with jumper cables:
* `0` to `CD1_SDA`
* `1` to `CD1_SCL`
Expand All @@ -24,11 +24,11 @@ dtoverlay=vc4-kms-dsi-7inch
----
. Reboot your Compute Module with `sudo reboot`. Your device should detect and begin displaying output to your display.

=== Connect a display to DISP0
=== Connect a display to DISP0/DSI0

To connect a display to DISP0:
To connect a display to DISP0/DSI0:

. Connect the display to the DISP0 port on the Compute Module IO board through the 22W to 15W display adapter.
. Connect the display to the DISP0/DSI0 port on the Compute Module IO board through the 22W to 15W display adapter.
. _(CM1, CM3, CM3+, and CM4S only)_: Connect the following GPIO pins with jumper cables:
* `28` to `CD0_SDA`
* `29` to `CD0_SCL`
Expand Down Expand Up @@ -61,3 +61,21 @@ To entirely ignore the display when connected, add the following line to `/boot/
----
ignore_lcd=1
----

== Attaching the Touch Display 2 LCD panel

Touch Display 2 is a 720x1280 7" LCD display designed specifically for Raspberry Pi devices (see https://www.raspberrypi.com/products/touch-display-2/). It connects in much the same way as the original touch display, but the software setup on Compute Modules is slightly different as it uses a different display driver. See xref:../accessories/touch-display-2.adoc[Touch Display 2] for connection details.

Edit the /boot/firmware/config.txt file and add the following to enable Touch Display 2 on DISP1/DSI1.

[source,ini]
----
dtoverlay=vc4-kms-dsi-ili9881-7inch
----

To use DISP0/DSI0 use the following:

[source,ini]
----
dtoverlay=vc4-kms-dsi-ili9881-7inch,dsi0
----
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