Hardware
Raspberry Pi Pico W and a level shifter — that's the core.
The Pico W's PIO (Programmable IO) handles the timing-critical bus protocol in hardware, independent of WiFi or CPU. This solves the reliability issues that plague ESP8266/ESP32 implementations.
MCU Board
Raspberry Pi Pico W
Dual-core ARM Cortex-M0+, WiFi, USB-C, and crucially — PIO state machines that run independently of the main CPU. Perfect for bit-banged protocols with strict timing.
Why Pico W?
PIO
Hardware state machines handle 100kHz timing perfectly
~$6
Cheap enough to experiment and have spares
ESPHome
Full support via RP2040 platform
Comparison
| Feature | ESP8266 | ESP32 | Pico W |
|---|---|---|---|
| WiFi interrupts timing | Yes — major issue | Yes — less severe | No — PIO independent |
| Button reliability | Poor | Moderate | Excellent |
| Hardware state machine | No | No | Yes (PIO) |
| Price | ~$3 | ~$4 | ~$6 |
| ESPHome support | Yes | Yes | Yes |
Level Shifter
BSS138 Bidirectional Level Shifter
The Intex bus runs at 5V TTL. The Pico W is 3.3V and not 5V tolerant. A BSS138-based level shifter module handles bidirectional translation for DATA, CLK, and HOLD.
Pre-made 4-channel modules cost ~$0.50 on AliExpress. Include pull-up resistors, just connect and go.
Bill of Materials
| Component | Part | Purpose | Price |
|---|---|---|---|
| MCU | Raspberry Pi Pico W | WiFi, PIO for timing | ~$6 |
| Level Shifter | BSS138 module (4-ch) | 5V ↔ 3.3V for bus signals | ~$0.50 |
| Capacitor | 10µF electrolytic | Power supply filtering | ~$0.10 |
| Wires | Dupont/hookup | To 5-pin connector | ~$0 |
| Enclosure | IP65 box | Weather/splash protection | ~$3 |
Total: ~$10 (~$7 without enclosure). Power comes from the Intex 5V rail — no external power supply needed.
Optional: 3D Printed Connectors
To avoid cutting the control panel cable, you can 3D print compatible connectors:
- Intex PureSpa connectors by Psykokwak
- Full case with connectors for esp8266 PCB