[Release] DJTPMS Tire Pressure Monitoring System using BLE

Share your Projects! Custom Integrations
1

I’m happy to share my latest integration:

I recently bought a TPMS from China for my motorcycle. After setting up an ESPHome Bluetooth proxy, I discovered that this TPMS uses slightly different logic compared to others — its manufacturer ID keeps changing in the advertisements. Because of this, I decided to implement a custom integration for it.

I spent quite some time debugging the issue and reverse-engineering the CRC method, so I wanted to share the results with everyone.

If the name you see in the advertisement monitor is “DJTPMS,” you’re in luck.

DJTPMS
DJTPMS300×300 10.3 KB

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DJTPMS

DJTPMS is a Home Assistant integration that listens to Bluetooth LE advertisements from DJTPMS sensors and exposes their readings as sensors.

DJTPMS sensors are commonly sold as generic tire pressure sensors on AliExpress.

This integration uses passive Bluetooth scanning only and does not connect to the device.

Installation

HACS:

  1. Add this repository to HACS as a custom repository (Integration).
  2. Install DJTPMS.
  3. Restart Home Assistant.

Manual:

  1. Copy custom_components/djtpms to /config/custom_components/djtpms.
  2. Restart Home Assistant.

Configuration

You can add DJTPMS from the Home Assistant UI.

Open your Home Assistant instance and start setting up a new integration.

Notes:

  • Bluetooth must be enabled in Home Assistant.
  • The device must be in range and actively advertising.

Entities

The integration creates the following sensor entities per device:

  • Battery voltage (V)
  • Temperature (°C)
  • Absolute pressure (kPa)
  • Gauge pressure (kPa)

Gauge pressure is derived by subtracting a fixed 101 kPa atmospheric pressure from the absolute pressure.

Bluetooth Payload Format

The DJTPMS advertisement frame is parsed from manufacturer or service data. The core 12-byte payload layout is:

00 00  1F 27  01 54  00  06  0C 3D 5E 4E 8B E6
|  |    |  |   |  |   |   |   \______________/
|  |    |  |   |  |   |   \---- CC = CRC8 check byte
|  |    |  |   |  |   \-------- FF = flags/unknown (often 00)
|  |    |  |   \--\----------- PH PL = abs pressure (kPa), big-endian uint16
|  |    \--\------------------ TT = temperature (°C)
|  \-------------------------- VV = battery*10  (e.g. 0x1F => 3.1V)
\----------------------------- CID0 CID1 = “Company ID” bytes (varies: 00 00 or 00 0C)

Calculations

Derived values follow the parsing logic in custom_components/djtpms/ble.py and constants in custom_components/djtpms/const.py:

  • Battery voltage (V) = VV / 10.0
  • Temperature (°C) = signed int8 conversion of TT (0…255 → -128…127)
  • Absolute pressure (kPa) = (PH << 8) | PL (big-endian uint16)
  • Gauge pressure (kPa) = max(absolute_pressure - 101, 0)

CRC8 is computed over [CID0, CID1, VV, TT, PH, PL] and compared to CC.

Support

If you have discovered a problem or want to request a feature, please open an issue.

Pull requests are welcome.

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2

Thanks mate for the good job; that’s exactly what I was looking for!
Do you also happen to have any BLE sensors to recommend?
I’m struggling to find one that I can use safely and reliably to read data from it.

3

Personally, I have only ever use this one, as newer car has this kind of thing built-in. So I couldn’t really recommend something else.

If you ask me if this thing work? Yes, absolutely. Pressure is very sensitive with high precision. The rest, not so much, they do provide tire temperature and also the battery voltage, but it’s very low resolution, can be useful for making trend like temperature rising.
The update frequency seems to be higher while riding. Since Bluetooth proxy is at my home. When I get back, sometimes it takes a few seconds for the data to shows up, sometime it takes 3 minutes.

1 Like