WiFi + Home Assistant control for the Intex PureSpa with the SB-H20 control panel (the older, non-WiFi pump), via a BSS138 level shifter tapping the ribbon between the control panel and the mainboard — no board replacement, no soldering on the spa itself.
Tested on: Intex 28431E PureSpa Plus (SB-H20 panel). The SB-H20 plug/pinout is shared with the SSP and SJB models, so this should also apply to SimpleSpa SB-B20, SSP-H-20-1, and SJB-HS.
The SB-H20 button protocol is timing-critical (the panel pulls DATA low for ~2 µs windows). How well a board hits that timing while running WiFi is the whole story:
| ESP32 / M5Stack Atom Lite ⭐ recommended | ESP8266 / Wemos D1 mini | |
|---|---|---|
| Button timing | ISRs pinned to core 1, WiFi on core 0 → can't be preempted | single core — WiFi can disrupt the 2 µs pulse (occasional missed presses) |
| CPU tweak | none | must force 160 MHz |
| Boot quirk | none on G19/22/23 | needs 470 Ω series resistors to boot with cables attached |
| Measured power | ~66 mA / ~120 mA peak | ~20–100 mA |
| Component | this repo's intexsbh20 (ESP32 port of piitaya) |
piitaya/esphome-intexsbh20 |
| Guide | → esp32-atom/ | this page (below) |
Use the ESP32 / Atom Lite build (validated on a 28431E PureSpa Plus — temperature
plus all controls) unless you specifically want the ESP8266 — the second core solves the
timing-reliability problem that makes button presses flaky on the '8266. Both share the same BSS138 wiring and the same spa-side tap; only the
controller and a couple of details differ. (The Raspberry Pi Pico W is a third option
— RealByron/PicoW-Intex-PureSpa
— which offloads timing to PIO.)
Left: ESP8266 / Wemos D1 mini. Right: ESP32 / M5Stack Atom Lite (BSS138 + 470 Ω + screw terminals on an ElectroCookie Mini).
→ ESP32 build (recommended): esp32-atom/README.md
Exposes a climate thermostat, Power/Filter/Bubble switches, a water-temperature sensor, an Error text sensor and a Problem binary sensor — with all controls non-blocking so the Home Assistant connection never stalls. Full wiring, pins and flashing are in that guide.
The rest of this page is the ESP8266 / Wemos D1 mini build.
Open
wiring/sbh20-wiring.htmlin a browser for the same diagram interactively.
| Part | Notes |
|---|---|
| Wemos / LOLIN D1 mini (ESP8266) | ESP12/HUZZAH also work |
| BSS138 4-channel level shifter | not TXS0108E — auto-direction chips fight the open-drain DATA line |
| 3 × 470 Ω resistors | series on each signal line (see gotcha #4) |
| Inline fuse, ~250–500 mA | on the 5 V tap — protects the spa mainboard (see gotcha #6) |
| Cable tap / 3D-printed connector | to splice the panel↔mainboard ribbon |
| Hookup wire, perfboard, IP-rated box | permanent outdoor install |
Total ≈ $8–15. Power draw is tiny: ~20 mA idle, ~70 mA on WiFi, ~100 mA at power-on — size the fuse just above the inrush.
These are the exact multi-packs used for the unit pictured above (links are not affiliate links — substitute equivalents freely):
| Part | Product |
|---|---|
| D1 mini (ESP8266, ESP-12F) — 5 pk | Hosyond D1 Mini NodeMcu — https://www.amazon.com/dp/B09SPYY61L |
| BSS138 4-ch level shifter — 10 pk | HiLetgo 4-Channel I2C Bi-Directional — https://www.amazon.com/dp/B07F7W91LC |
| Solderable proto board — 6 pk | ElectroCookie Mini PCB Prototype Board — https://www.amazon.com/dp/B081MSKJJX |
| IP68 outdoor enclosure | MAKERELE Small External Junction Box — https://www.amazon.com/dp/B0D3GR7CWB |
Still need separately: a small screw-terminal block (used here to land the spa cable), 3 × 470 Ω resistors, hookup wire, and a way to tap the panel ribbon.
Spa cable colors vary by production batch — verify yours with a meter. On this unit the colors were:
| Spa wire | Function | BSS138 | Series R | D1 mini |
|---|---|---|---|---|
| red | +5 V | HV | — | 5V pin |
| green | GND | GND | — | G |
| white | CLK | HV1 ↔ LV1 | 470 Ω | D5 / GPIO14 |
| yellow | DATA | HV2 ↔ LV2 | 470 Ω | D6 / GPIO12 |
| black | LATCH | HV3 ↔ LV3 | 470 Ω | D7 / GPIO13 |
- BSS138 HV ← red 5 V, LV ← D1 mini 3V3 (both references required).
- All grounds common (spa green ↔ BSS138 GND ↔ D1 mini G).
- The D1 mini is powered from the spa's 5 V (red) in normal use.
| Reading | Meaning |
|---|---|
| steady 5 V | the supply (only one wire) |
| 0 V steady + continuity to chassis | GND |
| ~2.5 V (50 % duty avg) | CLK (free-running clock) |
| ~3 V (mostly high, active) | DATA (open-drain, idle high) |
| ~4.5–5 V (idle high, brief pulses) | LATCH (per-frame strobe) |
Multiple wires can read ~5 V — those are idle-high signals, not power. The real supply is the one that's dead steady.
- Wire colors are not standard. red≠5V on every unit. Measure. The supply is whichever wire is a rock-steady ~5 V; idle-high signals also read ~5 V.
- CPU must be 160 MHz. Reads work at 80 MHz but button TX silently fails.
Set
board_build.f_cpu: 160000000Land Clean Build (the flag often doesn't apply on an incremental build). Verify at runtime withESP.getCpuFreqMHz(). - Use BSS138, not TXS0108E. The DATA line is open-drain with a pull-up; the TXS0108E's auto-direction sensing fights it. BSS138 is purpose-built for this.
- 470 Ω series resistors on the signal lines. Without them the ESP8266 may fail to boot with the cables connected — the 5 V signals back-power the chip through the level shifter / GPIO clamp diodes before the rail is up. The resistors limit that injection. (Also keep signals on D5/D6/D7 — never the D3/D4/D8 strap pins.)
- Never power USB + spa at the same time. Flash on USB, then run on spa 5 V only. Future updates go over OTA.
- Fuse the 5 V tap (~250–500 mA). The spa mainboard's spare current budget is unknown — a fault in your add-on could damage it. An inline fuse just above the ~100 mA power-on inrush protects the board. (via jnsbyr's hardware notes.)
- Button presses can be occasionally unreliable. On the ESP8266, WiFi processing preempts the timing-critical signalling, so a press is sometimes missed or doubled. Keep WiFi signal strong (RSSI) and expect the rare retry. The underlying firmware re-reads state after each press to self-correct. This is inherent to ESP8266 — the Pico W version avoids it with PIO.
- Copy
esphome/secrets.yaml.example→secrets.yamland fill in WiFi + a generatedapi_key/ota_password. - First flash over USB (D1 mini only, not wired to the spa). Then OTA forever after.
- Wire to the spa per the table, power from spa 5 V, confirm the
water_temperatureentity reads correctly and a button (Power/Bubble) activates.
esphome/intex-spa.diagnostic.yaml is a throwaway firmware that turns the three GPIOs
into frequency counters — handy for identifying CLK (highest edge rate) when sorting
the signal wires.
tools/esp_log_monitor.py streams the device's logs over the native API from a PC
(no ESPHome CLI needed) — set the address + noise PSK at the top.
piitaya/esphome-intexsbh20— the ESPHome componentjnsbyr/esp8266-intexsbh20— protocol reverse engineeringDIYSCIP(Geoffroy HUBERT) — the receive-decode code the bundledSBH20IO.*capture is derived from (CC-BY-NC-SA-4.0)RealByron/PicoW-Intex-PureSpa— Pico W variant
MIT — see LICENSE — except the bundled intexsbh20 receive code
(components/intexsbh20/SBH20IO.* and the esp32-atom/ copy), which is derived from DIYSCIP
and licensed CC-BY-NC-SA-4.0 (non-commercial). See the file headers and
esp32-atom/README.md.