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Android mainboards · Touch displays · Firmware — since 2013
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Drive multiple displays

Some KTM boards drive more than one screen with independent content — not a mirror. A menu board on HDMI and an order screen on the panel, from one device. This guide covers what the hardware allows and how to control each output.

First: what your board and chip allow​

Display capability is set by the SoC, then by which connectors the board populates. Check both:

SoCIndependent displays
RK3588Up to 4
RK3576Up to 3
RK3568Up to 3 (2 simultaneous on most boards)
RK3566Up to 2

Then the board page tells you which physical outputs exist (HDMI, eDP, MIPI-DSI, LVDS) and which are wired. A chip that supports three displays on a board that exposes two connectors gives you two. See your board page.

Independent vs mirrored​

By default Android may mirror. For different content per screen you present to each display's context — standard Android Presentation / multi-display APIs drive what shows on each output. ItempApiPub controls the physical side of each panel: brightness, orientation, backlight, and whether HDMI is on.

import com.itemp.itempapi.ItempApiPub;

// Turn the HDMI output on (e.g. the second screen)
ItempApiPub.setHDMIoutEnable(context, true);

Per-panel orientation​

A common multi-screen build has one landscape and one portrait panel. Set an absolute angle rather than stepping:

ItempApiPub.setScreenOrientation(context, "90");   // "0" | "90" | "180" | "270"

See Display for absolute vs stepped rotation — mixing the two models in one app makes the current angle hard to track.

Per-panel brightness and blanking​

Independent brightness lets an indoor order screen and a bright-window menu board run at different levels, and lets you blank one screen on a schedule while the other stays live:

ItempApiPub.setScreenBrightness(context, "200");     // "0"–"255"
ItempApiPub.setBacklightEnable(context, false);      // blank a panel, board alive

Touch maps to the wrong screen — the classic bug​

On a multi-touch, multi-display build, touch input frequently lands on the wrong panel until the input-to-display mapping is set. If taps on screen B register on screen A, this is why. The fix is in the platform display/input configuration, not in ItempApiPub — flag it to your account manager for your specific panel combination, and test touch on every screen before shipping.

Practical notes​

  • Simultaneous limits are real. RK3568 supporting "three displays" often means two at full resolution at once on a given board. Confirm the combination you need on your board rather than assuming the chip maximum.
  • MIPI-DSI panels need timing set for the exact panel — that is done in the device tree at the factory, not from your app. Tell us the panel when ordering.
  • Blank, don't power off, for scheduled dimming if the other screen must stay up — setBacklightEnable blanks one panel without touching the board or the other output.