The ESP32-P4 DJ rig that replaces a laptop in the booth

The ESP32-P4 DJ rig that replaces a laptop in the booth

The ESP32-P4 — Espressif's new high-performance chip with dual RISC-V cores and, for the first time in the family, real USB capabilities — has been finding one impressive demo after another this year. The most complete so far: Pajoniiir BL-A1800, a standalone dual-deck DJ system by Daniel Vučinović that Hackaday covered in September 2026. The project repository is MIT-licensed and public, with nearly a thousand commits behind it.

What it does

Pajoniiir replaces the laptop that traditionally sits between a DJ controller and the speakers. Two ESP32 boards split the work:

• A Seeed XIAO ESP32-S3 acts as USB MIDI host for a Pioneer DDJ-FLX4, translating controller events and streaming the FLX4's USB headphone output back to the operator.
• An ESP32-P4 multimedia board with a 4.3-inch Guition touch display owns playback: it reads a USB stick carrying a Rekordbox music library, renders waveforms and deck state through LVGL, and does the audio DSP, mixing and cue routing out through a PCM5102A DAC.

It plays MP3, WAV and FLAC directly from the stick. No PC on stage, no operating system nagging for an update ten minutes before your set. As Hackaday put it, it does most of what a laptop would do — it just costs around US$50 in silicon and won't blue-screen mid-performance.

The deck view is the part worth seeing: scrolling waveforms for both tracks, beat position, deck state and a mixer overlay, all redrawn on the touch panel while audio runs continuously underneath. On a laptop this is trivially easy — GPUs eat it for breakfast. On a microcontroller it means the same redraw budget that desktops spent on eye candy has to fit alongside MP3 decode, USB file reads and mixing maths. That Pajoniiir holds the UI at a usable refresh rate while streaming lossless FLAC off a stick is the real engineering claim here, and it's the reason the P4 is doing the media half rather than the S3.

Inside the P4, and why this build wasn't possible a year ago

The ESP32-P4 is a different animal from the WiFi chips you know. It's a dual-core RISC-V design running up to 400 MHz, with 32 MB of PSRAM support and hardware acceleration for the parts of this build that matter: a JPEG codec, audio coprocessor, and a MIPI-DSI display interface driving the touch panel directly. What it deliberately doesn't have is radio — no WiFi, no Bluetooth — which is why the S3 sits alongside it as the network-and-MIDI half.

USB is the headline. Older ESP32s implemented USB as a device: they could be a keyboard or a serial port, but they couldn't host one. The P4 has a native USB 2.0 High-Speed host/controller pair, which is what lets it mount a FAT-formatted music stick and talk MIDI to a controller over the same standard your laptop uses. MIDI over USB Host on the S3 goes through a software stack that's clever but picky; on the P4 it's silicon. Waveform rendering is the other half: LVGL, the open-source graphics library behind a long list of embedded UI projects, gets hardware-accelerated blitting on the P4's display pipeline. Drawing two scrolling waveforms plus a mixer view at 60 fps on a $9 chip would have been a compiler-fuelling exercise a year ago; here it's just what the render loop does between MP3 frames.

The resulting division of labour is worth copying even if you never build a DJ rig: put the screen-and-media work on the chip built for it, and the radio-and-protocol work on the chip built for that. Half the P4 demos this year are really that pattern wearing different costumes.

For Australian builders, the closest stocked hardware today is our StealthDeck Pro (A$119) on the ESP32-S3 side — the S3 half of the Pajoniiir architecture (USB MIDI host for HID-class devices) is within reach of it. The P4 boards themselves aren't in the store yet; we're watching the module supply situation the same way everyone else is.

The honest caveats

This is a performance instrument built by one person, not a product. Three things to know before you imitate it:

1. Library support is narrow. It reads Rekordbox-exported media. If your collection lives in another DJ app's format, you'll be converting first.
2. Two-controller USB is exactly two-controller USB. The demo drives one DDJ-FLX4 plus a stick; don't assume arbitrary USB topologies will work.
3. It's a build, not a buy. You'll need the Guition 4.3-inch P4 display combo, a XIAO S3, the DAC module, and patience with a young codebase. The 938 commits tell you this was months of work.

A fourth caveat the write-ups tend to skip: latency. Laptop DJ software sits in the same position — controller, processing, output — and musicians notice round-trips above roughly ten milliseconds. Pajoniiir's architecture keeps the MIDI path short and does the mixing on the P4's audio coprocessor, but you're relying on one developer's tuning. If you build it and the cue feel is off, that's your problem to debug, not a support desk's. Meanwhile the money argument still lands in the build's favour: a used laptop capable of running DJ software costs several hundred dollars and ages badly; the P4 boards cost about US$50 and don't care what year it is. Though the laptop plays nicer with a broader range of controller classes, and it runs your existing software — the build wins on cost and reliability, not flexibility.

Building the P4 half yourself

If you want to attempt it, the parts list is mercifully short and everything but the display combo is generic. The Guition 4.3-inch ESP32-P4 board is the one specific item — it pairs the chip with the touch panel Pajoniiir's display code targets, and substituting another P4 board means reworking the LVGL display driver init. The XIAO S3 costs about A$15, the PCM5102A module A$8, and the rest is wiring. Build order matters: get the P4 rendering a static LVGL screen first, then file browsing off a USB stick, then audio out, and only then wire the two boards together with the MIDI link. Trying to debug all four layers at once is how a weekend project becomes a month. The repository's issues tab is active, and the developer answers — a real advantage over the abandoned-code graveyard most hardware projects end up in.

If you want the touch-display side of this without the P4 learning curve, our CYD PDA post shows how far the older ESP32 display boards already go — and StealthDeck Pro is the assembled way to get an S3 deck on your bench today.

Lawful use

DJ controllers and music playback raise none of the radio-regulation questions that other ESP32 projects do — the only legal note worth making is the one about your music library: play music you're licensed to play publicly if anyone besides yourself is listening. That's an Australian Performing Right Association matter, not a hardware one. Bedroom practice with the door shut is nobody's business; a gig at a licensed venue is already covered by the venue's blanket licence in most cases, but a market stall or a pop-up is on you to check.

Affiliate disclosure: products linked above are sold in our own store.

Sources: Hackaday — "Standalone DJ System Runs On ESP32" · dvucinozd/Pajoniiir on GitHub · Espressif ESP32-P4 · LVGL — Embedded Graphics Library. Links verified live 2026-10-07.

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