alerTire Open Protocol TPMS

The alerTire Open Protocol TPMS is designed to help app developers, technology innovators, and fleet integrators seamlessly integrate their solutions with our smart tire pressure monitoring sensors. Built on Bluetooth Low Energy (BLE), the protocol reflects our mission to enhance road safety and smarter mobility. Developed through real-world customer feedback, on-road testing, and collaboration with industry partners, it offers all the essential details you need, including sensor duty cycle information, communication packet structures, and sample code in Python (for Raspberry Pi) and C (for ESP32). With this open protocol, integration becomes simple, flexible, and reliable—empowering you to create applications that improve safety, performance, and efficiency.

alerTire Open Protocol TPMS

Each TPMS sensor functions independently while following a consistent duty cycle throughout its lifetime. Every sensor is assigned a unique ID, which is printed on its surface for easy identification. At regular intervals of one minute, the sensor transmits Pressure, Temperature, and Voltage (PTV) values along with its unique ID. These PTV values are broadcast as non-connectable advertisement packets across all three Bluetooth Low Energy (BLE) channels. Each advertisement runs for 10 seconds with a packet interval of approximately 852 milliseconds.

Packet Structure

Packet Structure(19 bytes)

Non-connectable packet format

Pressure Data(17-18)

Pressure values can be extracted from the 17th and 18th bytes of the advertisement packet. The transmitted pressure is reported in kPa.

MSB
0 1 2 3 4 5 6 7
17th Byte
0 0 0 0 0 1 0 1
0 1 2 3 4 5 6 7
18th Byte
0 1 1 1 1 0 0 0
LSB

Note:

  • Maximum pressure value (decimal): 1400 units

  • Maximum pressure value (binary): 010101111000

  • Bits allocated for pressure measurement: 11 bits (sufficient to represent up to 1400 kPa)

Pressure Data Parsing

  • Maximum Pressure Range (Standard Sensor): 0 – 700 kPa

  • Maximum Pressure Range (Truck Sensor): 0 – 1400 kPa

Calculation of Actual Pressure Data:
The pressure value (in kPa) is transmitted as a hexadecimal value within the advertisement packet. This hex value needs to be parsed and converted to obtain the actual pressure reading in kPa.

For example:
  • Value from the advertisement = 0x01 0x5E
  • Convert it into decimal = 350
  • Pressure value = 350 kPa
For psi conversion:
  • Value from the advertisement = 0x01 0x5E
  • Convert it into decimal and divided by 6.895 = 350 / 6.895
  • Pressure value = 50.76 psi

Temperature(16)

We can get the temperature data from the 16th byte of the advertisement data. Transmitted Temperature value is in ℃. The most significant bit represents whether the transmitted temperature is -ve or +ve. If the MSB is set to 1, then the value is -ve.

MSB
0 1 2 3 4 5 6 7
16th Byte
0 1 1 1 1 1 0 1
LSB
Note:

Max Temperature units(In binary)
– 01111101 (Positive temperature)
– 11111101 (Negative temperature)
Max Bits used for Temperature level – 8 bits

Temperature Data Parsing

Maximum Supported Temperature Range:

  • -20 ℃ to 105 ℃

Data Calculation:
Temperature values are transmitted as hexadecimal data in the sensor advertisement.

For example:

Positive Temperature(MSB 0th bit “0”)
  • Value from the advertisement = 0x19
  • Convert it into signed integer = +25
  • Temperature Value = +25 ℃
Negative Temperature(MSB 0th bit “1”) :
  • Value from the advertisement = 0xFA
  • Convert it into signed integer = -6
  • Temperature Value = -6 ℃

Battery Data(15)

We can get the battery data from the 15th byte of the advertisement data. Transmitted battery voltage data must be divided by decimal 10 to obtain actual battery voltage level.

MSB
0 1 2 3 4 5 6 7
15th Byte
0 0 1 0 0 0 0 1
LSB
Note:

Max Battery units(In decimal) – 33 units
Max Battery units(In binary) – 00100001
Max Bits used for Battery level – 6 bits

Battery Data Parsing

Maximum Supported Battery Values:

  • 3.3 V / 3.0 V (may vary depending on the sensor model)

Data Calculation:
Battery values are transmitted as hexadecimal data in the sensor advertisement.

Example Calculation:

  1. Value from advertisement: 0x21

  2. Convert hex to decimal: 0x21 = 33

  3. Divide by 10: 33 / 10 = 3.3

Result: Battery value = 3.3 V

Premium Support & Customization
We provide premium support services and handle customization requests for our communication protocol, ensuring seamless integration with your device.

Important Notice: The alerTire App does NOT support Open Protocol TPMS from other brands. The protocol described here applies only to alerTire Open Protocol sensors. To integrate your device with our sensors using this protocol, ensure you purchase sensors labeled as Open Protocol on our store page.

Model Compatibility: Currently, only 4W Internal TPMS supports alerTire Open Protocol. Support for additional TPMS models is coming soon.

Availability: alerTire Open Protocol TPMS is currently available only for Indian customers. International availability will be announced shortly.

Sample Python Code
(runs on Raspberry Pi)

DOWNLOAD

Sample C Code
(runs on ESP-32)

DOWNLOAD

For any queries, contact our team

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