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Powkiddy X55

Overview

Hardware

SoC CPU GPU
Rockchip RK3566 ARM Cortex-A55 (Quad-core) @ 1.8 GHz Mali G52
Display RAM eMMC Connectivity
5.5-inch 1280*720 2 GB LPDDR4X (except some revisions which only have 1 GB) 8 GB (except early revisions) 2.4/5 GHz WiFi + BT (8821CS)

Software

Kernel GPU drivers Compositor Interface
Mainline Linux libmali (GLES 3.2) & Panfrost (GL 3.1/GLES 3.1) Sway Emulation Station

Tweaks

In Emulationstation system settings you find an overclock setting and undervolt options. The overlock option enables 2 GHz operation. While there are 3 levels of undervolting, where L1 is the least undervolt and L3 is the most undervolt. Undervolting can help performance in higher end emulators such as PPSSPP and Yabasanshiro standalone, due to less thermal throttling. As well as less battery drain on lower end emulators.

Obviously it can't be guaranteed that all specimens can undervolt and hence you may end up with a non-booting or unstable system. If this is occurs, the undervolting can be reversed by:

  1. Inserting the OS SD card into a PC.
  2. Open ROCKNIX partition, and go to the extlinux folder.
  3. Open extlinux.conf text file.
  4. Completely remove the line that starts with FDTOVERLAYS.
  5. Now your device will boot with stock voltages.

Features

Feature                 Notes
Storage ROCKNIX can be installed to the emmc or run from an SD Card, and an second SD card can be used to store games
Wifi Can be turned on in Emulation Station under Main Menu > Network Settings
Bluetooth Supports bluetooth audio and controllers

Controls

RetroArch Hotkeys

Button Combo Action
SELECT+START (x2) Quit Game
SELECT+R1 Save State
SELECT+L1 Load State
SELECT+X(NORTH) Open RA Menu
SELECT+B(SOUTH) Reset Game
SELECT+Y(WEST) Show FPS
SELECT+A(EAST) Take Screenshot
SELECT+R2 Fast-Forward

Notes:

  • By default ROCKNIX will detect your controller and configure RetroArch hotkeys automatically. This is controlled by the "AUTOCONFIGURE RETROARCH HOTKEYS" option in the Settings > Controller & Bluetooth menu. While the option is enabled, RetroArch hotkeys will be overwritten by the above defaults each time RetroArch is launched. If this behavior is not desired that option can be disabled and your user-defined RetroArch hotkeys will be used instead.

Mednafen Hotkeys

Button Combo Action
SELECT+START (hold for 2sec) Quit Game
SELECT+R1 Save State
SELECT+L1 (hold for 2sec) Load State
SELECT+Y(WEST) Show FPS
SELECT+R2 Fast-Forward
START+L1 Select disc
START+R1 Eject/Insert disc
START+D-Pad Left Decrease save slot by 1
START+D-Pad Right Increase save slot by 1
START+L2 Configure buttons on virtual port 1
START+R2 Insert coin

Notes:

  • By default ROCKNIX will expand the configuration file according to the first controller mednafen finds. This only happens when the config file doesn't exist (meaning the first time or if you manually delete it). After the initial expansion you are free to customize the controls.

Mupen64Plus-SA (Nintendo 64)

Button Combo Action
START Start
B(SOUTH) A
Y(WEST) B
Right Analog Up C Up
Right Analog Down C Down
Right Analog Left C Left
Right Analog Right C Right
L2 Z
L1 L
R1 R
SELECT+START Quit Game
SELECT+R1 Save State
SELECT+L1 Load State
SELECT+Y(WEST) Take Screenshot
SELECT+B(SOUTH) Reset Game

Notes:

  • Z and L button assignment can be changed directly in EmulationStation
    • Highlight the game and press X(NORTH)
    • Select ADVANCED GAME OPTIONS
    • Set EMULATOR to MUPEN64PLUSSA
    • Then change INPUT ONFIGURATION
      • Default: L1 = L, L2 = Z
      • Z & L SWAP: L1 = Z, L2 = L
  • You can also create your own custom controller configuration and add it to /storage/.configs/game/configs/mupen64plussa. Then update INPUT CONFIGURATION to CUSTOM following the same steps as above.

PPSSPP-SA (PSP)

Button Combo Action
START Start
SELECT Select
A(EAST) Circle
B(SOUTH) Cross
X(NORTH) Triangle
Y(WEST) Square
L1 L
R1 R
R2 Save State
L2 Load State
L3 Open Menu

Hypseus-singe (Daphne)

Button Combo Action
SELECT+START Quit Game
SELECT Coin
START Start
B(SOUTH) Button 1
A(EAST) Button 2
X(NORTH) Button 3

Notes:

  • To add/change mapping you can edit /storage/.config/game/configs/hypseus/hypinput.ini under [KEYBOARD] section by changing third number for a function from 0 (disabled) to a corresponding joystick value. You can identify joystick values by running jstest /dev/input/js0 over ssh.

  • For example the following would assign quit to L1 and pause to R1

    [KEYBOARD]
KEY_QUIT = SDLK_ESCAPE 0 5
KEY_PAUSE = SDLK_p 0 6

Duckstation (PSX)

Button Combo Action
SELECT+R1 Save State
SELECT+L1 Load State
SELECT+R2 Fast-Forward
SELECT+X(NORTH) Open Menu
SELECT+A(EAST) Screenshot
SELECT+START Quit Game
Supported Bios Files Path
List /roms/bios

Global Hotkeys

Button Combo Action
L1+START+SELECT Exit Emulator / Application
SELECT+Vol + Brightness Up
SELECT+Vol - Brightness Down
START+Vol + LED on
START+Vol - LED off
SELECT+START+Vol + WIFI enable
SELECT+START+Vol - WIFI disable

Emulators

Notes

Installation

Download the latest RK3566-X55 version of ROCKNIX from the button below and follow the instructions listed on the Install page.

Latest Version Latest Version

Power Saving

As of 16 January 2025 the following power saving options are working on the Powkiddy X55:

  • Enhanced Power Saving
  • CPU Power Saving
  • Audio Power Saving
  • Wifi Power Saving
  • PCIE Active State Power Management
  • Runtime Power Management

Keep in mind that these settings are not guaranteed to work on future versions of ROCKNIX and might impact the experience (e.g longer Wifi connection times after resuming from sleep).

Screen Calibration

Retroarch

The Powkiddy X55 screen is miscalibrated from the factory. While there's no universal fix (yet) this issue can greatly be mitigated by using a Retroarch Shader. Instructions for doing so are listed below:

  1. Start a game
  2. Open the "Quick Menu" in Retroarch by pressing both joysticks
  3. Navigate to "Shaders"
  4. Turn "Video Shader" to "ON"
  5. Navigate to "Load Preset"
  6. Select "Misc" -> "Image Adjustment"
  7. Go to "Shader Parameters" and change the following parameters:
  8. Target Gamma -> 2.50 (see Target Gamma)
  9. Monitor Gamma 1.70
  10. Saturation -> 1.40
  11. Contrast -> 1.10
  12. Black Level -> -0.15
  13. Optionally you may enable the following tweaks:
  14. Modify "Red Channel" -> 1.05 and "Blue Channel" -> 0.95 for a warmer screen temperature
  15. If your screen has a line of "garbage" pixels on the right, modify "X Modifier" -> "-0.00"
  16. Navigate back to the shader menu and pick "Save Preset"
  17. Select Either:
  18. Recommended: "Save Global Preset" to have this as the default for all Retroarch cores
  19. "Save Core Preset" to have this as the default for a specific system (e.g all PSX games)
  20. "Save Content Preset" to have this as the default for a specific directory (e.g all roms in a "RPG" directory)
  21. "Save Game Preset" to have this as the default for the specific game that you're running

The settings at 7 are just a proposal, you might want to experiment a bit to get something that matches your preferences but they should serve as a great starting point.

As a bonus, adjust the "Horizontal Overscan %" and "Vertical Overscan %" settings to deal with e.g PSX games that have black borders (such as Crash Tag Team Racing and Spyro).

The black bars on the sides when displaying 4:3 content will not be effected by shaders and might thus look lighter than the game image. If you find this distracting a (lighter) overlay will hide this issue.

PPSSPP

PPSSPP supports postprocessing shaders and a fix can be applied in a similar way as for Retroarch.

  1. Start a game
  2. Open the "Quick Menu" in PPSSPP by pressing down on the left joysticks
  3. Navigate to "Display layout & effects" and click on the "+" button
  4. Navigate to "Postprocessing shaders" and select "Color correction"
  5. Enter the following settings:
    • Brightness -> 1.0
    • Saturation -> 1.20
    • Contrast -> 0.85
    • Gamma -> 0.8
  6. Depending on the selected game you might want to tweak the settings above but they should serve as a good starting point.

Target Gamma

A Target Gamma of 2.5 matches closely with what CRT TVs targeted for. For darker games you might want to try a lower value. For handheld systems a gamma value of 1.8 - 2.2 is usually optimal. Below is a table of common retro handhelds with a suggested Target Gamma value.

Handheld Target Gamma / Display Characteristics Notes
Game Boy (Original) No specific gamma - 4 shades of gray, reflective, not backlit. No "gamma" in the traditional sense. The original Game Boy's display was very basic. Emulators often try to recreate its unique look, including the green tint, ghosting, and motion blur.
Game Boy Color Non-uniform, reflective LCD (~1.8 at the low end, ~2.2 at the high end) The GBC had a wider color palette and a brighter screen than the original Game Boy but was still reflective and not backlit. It's color reproduction is often described as washed out or muted.
Game Boy Advance Non-uniform, reflective LCD (~1.8 at the low end, ~2.2 at the high end), but often perceived as quite dark. The original GBA screen was notorious for being dark and difficult to see without direct light. The perceived gamma can appear higher due to the lack of a backlight.
Game Boy Advance SP (AGS-001) Frontlit LCD, closer to ~1.8-2.2 The first GBA model with a built-in light. While a significant improvement, the frontlight could create a washed-out look.
Game Boy Advance SP (AGS-101) Backlit LCD, closer to ~2.2 The most sought-after GBA model due to its brighter, backlit screen. Provides a more vibrant and modern display experience.
Nintendo DS (original & Lite) Backlit LCD, ~2.2 The DS features dual backlit screens and was significantly brighter than previous Nintendo handhelds.
Sega Game Gear Backlit LCD, ~1.8-2.2 (Similar to a dim CRT, but with potential for blurriness) The Game Gear had a backlit color screen, which was advanced for its time but still relatively dim compared to modern displays and prone to motion blur. The backlight could also have inconsistencies of its own.
Sega Nomad Backlit LCD, ~1.8-2.2 (Similar to Game Gear, potentially slightly brighter, with less blur) Essentially a portable Genesis, the Nomad also had a backlit screen. It might appear slightly brighter than the Game Gear and was updated during production from a double to single fluorescent bulb, getting slightly dimmer as a result. 
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