Kinsa Thermometer Protocol

Introduction

Kinsa makes BLE smart thermometers. Two models are documented: Herschel (ear) and Kelvin (stick). These are health measurement devices, not adult toys.

BLE Profile

Herschel (Ear Thermometer)

services:
  - uuid: "00000000-0068-746c-6165-4861736e694b"
    characteristics:
      - uuid: "00000004-0068-746c-6165-4861736e694b"
        properties: [write]
        role: tx
      - uuid: "00000002-0068-746c-6165-4861736e694b"
        properties: [notify]
        role: rx

Kelvin (Stick Thermometer)

services:
  - uuid: "00000000-006a-746c-6165-4861736e694b"
    characteristics:
      - uuid: "00000004-006a-746c-6165-4861736e694b"
        properties: [write]
        role: tx
      - uuid: "00000002-006a-746c-6165-4861736e694b"
        properties: [notify]
        role: rx

Response Format

Rx notifications: 0xAA 0xNN... where 0xAA is the OpCode.

OpCode Table

Event	Herschel OpCode	Kelvin OpCode
Temp notification	70	67
Firmware Version	2	2
Battery Voltage	10	10
Serial Number	8	8
RTC Date	6	6
RTC Counter	4	4
Next Cached Temp	65	69
Handshake complete	5	5
Error	—	7
Intermediate Temp	—	66
Temp Source	—	-76
Unknown	13	13

Notes

• These are health thermometers, not adult devices.
• BLE advertisement names are not documented.
• The service UUIDs embed ASCII text: 6165-4861736e694b decodes as aeHasnIK.

Sources

• GitHub Issue (stpihkal#46)