PxP Flip — OS Emulator

A browser emulator for the PxP Flip, a small 4G flip phone with no browser and no app store. It runs the real OS against a simulated hardware layer, so the whole phone can be built and used before any of it physically exists.

No install, no build step, no dependencies.

Try it: https://icet33.github.io/pxp-flip-emulator/

Then hold the red hangup key for 3 seconds to switch the phone on.

The split is deliberate. emulator.html pretends to be the physical device and holds no application logic. pxp_os.js is a port of the firmware that runs on the ESP32-S3.

To run it from your own machine, download all three and open emulator.html. If the OS does not load itself, click Load, pick pxp_os.js, and click Restart — browsers block local file reads, so that path still works offline.

The hardware panel on the right simulates the things a phone has done to it: incoming calls, incoming SMS, pulling the SIM, network loss, a flat battery.

The console is colour coded. Blue is hardware, green is the OS, red is an error.

Working

Home screen with clock and notification badges · dialer · multi-tap text input with accent folding · contacts, with add, delete, call and message · messages, threaded, send and receive · call log with icons, durations and delete · incoming calls, with ring, answer, decline, missed, ringtone picker and silence-on-volume · outgoing calls with dialing state and answer detection · volume with vibrate and silent · voice memos, record, pause, play, seek · camera with live preview and shutter · gallery · SIM PIN and PUK entry · settings · screen dim, sleep and outer-screen fade · Apps and Games submenus

Coming soon, on the phone as well as here

Calendar · notes · calculator · alarms · file explorer · music · wallet · Snake, Tetris, Blackjack, Starfall and Doom

The hardware layer and the OS talk through a deliberately narrow API. The hardware knows nothing about apps. The OS knows nothing about canvases. That is what lets the same code run here and on real silicon.

The OS asks the hardware for:

getBatteryPercent()      isFlipOpen()
getInnerBrightness()     getOuterBrightness()
setInnerBrightness(n)    setOuterBrightness(n)
requestInnerFrame()      requestOuterFrame()

plus modem, audio, storage, camera and sd.

The hardware tells the OS when something happens:

onPowerOn()        onPowerOff()       onButtonPress(btn)
onButtonRelease()  onFlipChange()     onBatteryChange()
onVolumePress()    onIncomingCall()   onCallConnected()
onCallEnded()      onSMSReceived()

Brightness changes are instant at the hardware level. Every animation, fade and timeout lives in the OS, which just calls setBrightness repeatedly. All state, all timers and all decisions belong to the OS.

The display is drawn with a hand-built pixel font. Digits are 3×5 grids of blocks with a one-block gap, so spacing scales with size automatically.

• ESP32-S3-WROOM-1, 16 MB flash, 8 MB octal PSRAM
• 2.4" TFT LCD, 320×240, ILI9341, inside
• 1.5" OLED, 128×128, SSD1351, outside
• A7670 4G modem — calls and SMS only, no data
• DVP camera on a flat flex
• microSD, removable battery, backlit keypad, USB-C, 3.5 mm jack

The OS runs on a breadboard today and makes real 4G calls with a real SIM. What does not exist yet is a PCB, a hinge or a shell.

Known missing on real hardware

• Call audio, both directions. The modem breakout does not bring out its PCM pins, so calls connect, ring and time correctly in complete silence
• Battery percentage is hardcoded to 100. No divider, no gauge, no charger
• No real-time clock. Time comes from NTP over WiFi, so with no WiFi the phone does not know what time it is
• No vibration motor, and no headphone jack circuit