Mira Activate for Home Assistant

A custom Home Assistant integration for controlling Mira Activate digital showers via Bluetooth Low Energy (BLE).

Works through ESPHome Bluetooth proxies — no USB dongle or direct BLE from the HA host required.

Sister integration to mira-ha (Mira Mode). The two products are different at the byte level so each has its own integration. See docs/ if you want the protocol reverse-engineering writeup.

Features

• BLE control via ESPHome proxies — uses HA's Bluetooth integration to route through your existing ESPHome BLE proxy mesh
• Auto-discovery — devices appear in HA's discovery feed once they advertise the Activate service UUID
• Outlet switches — Rain Head and Handheld, independent on/off
• Target temperature — slider 20–48 °C, 0.5 °C step
• Flow rate — slider 0–16 L/min, 0.25 L/min step (device cap)
• State sensors — measured water temp, target temp, current flow, raw outlet/status bytes for automation use
• Binary sensors — Running, Paused, Error, Session Ready
• Resilient session — one persistent BLE connection held alive by a keepalive, re-arming encryption from the stored SMP bond on every connect, eager reconnect on a dropped link, and per-entity optimistic state so toggles feel instant in HA. The SMP bond is never destroyed automatically — if it's genuinely lost, HA surfaces a guided re-pair step (see Setup).

Supported Devices

• Mira Activate digital shower (verified on a 2-outlet ensuite unit advertising as MIRA <hex> <ROOM>)

Any device advertising BLE service UUID 267f0001-eb15-43f5-94c3-67d2221188f7 should work.

Requirements

• Home Assistant 2024.1 or later
• Bluetooth reachable to HA — typically an ESPHome BT proxy within range of the shower
• ESPHome ≥ 2024.4 on the proxy (older firmware may not support the bluetooth_device_pair API used for the SMP bond)

Installation

HACS (Custom Repository)

1. HACS → ⋮ → Custom repositories
2. Add https://github.com/jonwilliams84/Mira-Activate-HA as type Integration
3. Install Mira Activate Shower
4. Restart Home Assistant

Manual

1. Copy custom_components/mira_activate/ into <config>/custom_components/
2. Restart Home Assistant

Setup

1. Settings → Devices & Services → Add Integration → Mira Activate Shower (or accept it from the discovery feed). Its name will be MIRA <hex> <ROOM>.
2. The setup walks you through a pairing step: put the shower into pairing mode at the panel (or power-cycle it so it's freshly pairable), then press Submit. HA establishes the SMP bond and verifies it before finishing.
3. The entities appear under the new device card.

The bond is created once and then reused. If it's ever lost (e.g. the proxy holding it was reset), HA raises a re-pair prompt — open the device → ⋮ → Reconfigure, put the shower in pairing mode, and Submit again. The bond must be (re)created while the unit is pairable; an unsolicited pair attempt is rejected by the firmware (error 82).

The bond lives in the NVS of the one proxy that paired it (ESPHome proxies don't share bonds), so the shower must connect through that proxy. Keep that proxy active: true and near the bathroom; scan-only proxies elsewhere are fine. Don't run two active proxies for one Activate — it stores a single bond.

Performance notes

End-to-end latency from HA toggle to water flowing is ~3-5 seconds, of which most is the shower's hardware valve actuation — not the integration.

HA-initiated changes (slider, toggles) appear instantly in the UI via optimistic state. Panel-side changes (pressing a button on the shower itself) reflect on the next successful poll, typically within the 25 s poll cycle. The integration holds the BLE link open continuously (a keepalive defeats the firmware's ~36 s idle-drop) and reconnects within ~2 s if it does drop, so commands ride a live connection. The 0x2B status read takes several seconds to answer when the device is idle, which is why feedback is optimistic rather than waiting on the device.

How it works under the hood

The Activate uses a fully different wire format from Mira Mode:

• Frame: [0xAA, 0x55, 0x00, opcode, body_len, payload, chk8]
• Integrity: 8-bit 2's-complement checksum (no CRC-16)
• Control opcode: 0xAB Set Temperature, byte 8 = bit-packed outlet bitmap
• Auth: LE bonding (SMP), no application-layer pair handshake. Over a proxy the bond's encryption is re-armed with pair() on every connect (the stored key isn't auto-applied) — see docs/PROTOCOL.md §3.1
• Reads via 0x2B Read Unit Prime, polled every ~25 s

The integration was reverse-engineered from the official uk.co.mirashowers Android app combined with a live HCI snoop capture of the app driving the shower. Detailed protocol writeup: docs/PROTOCOL.md.

Troubleshooting

A duplicate device keeps being "discovered." Fixed in 0.1.6. The Activate advertises under two name forms and older builds keyed identity on each separately, so an address rotation looked like a new unit. Update, restart HA, and it stops; any leftover duplicate device can be deleted from its device page.

CCCD ... Insufficient authentication, or the shower drops to unavailable. The Activate needs a bonded (encrypted) link. Two causes:

1. The bond is genuinely lost (the proxy holding it was reset/cleared). HA raises a re-pair prompt — open the device → ⋮ → Reconfigure, put the shower in pairing mode at the panel, and Submit. The integration never wipes the bond on its own (doing so strands the unit, since the firmware rejects an on-demand pair with error 82).
2. The connection is routing through a proxy that doesn't hold the bond. Make the one bonded proxy active: true and near the bathroom; set distant proxies scan-only so HA always connects via the bonded one.

If it still recurs with the bond intact, it's marginal RF — improve the proxy placement/signal near the shower.

Status

Alpha. Verified working on one 2-outlet ensuite Activate. Reports of behaviour on other models, and PRs, welcome.

License

MIT