This document describes the I2C flow and differential pressure sensors provided by Sensirion. These sensors are based on the SF04 chip and contain sensor information such as scale factor, measurement unit, and tracking information stored in the EEPROM. By reading the EEPROM, the scale factor, measurement unit, and serial number of the sensor can be obtained.
The document describes the procedure for retrieving calibration data stored in the EEPROM of Sensirion I2C flow and differential pressure sensors that use the SF04 chip. The sensor output is a 16‑bit integer that must be divided by a scale factor and interpreted with a measurement unit to obtain physical values.
Reading the EEPROM requires setting the internal address register with a specific command (e.g., 0xFA) and then issuing an I2C read. The scale factor is located at address h2B6, the measurement unit at h2B7, and tracking data such as serial numbers and part names are stored at other defined offsets. The document also details the coding of the 16‑bit measurement unit field.
| Sensor output format | 16‑bit integer |
|---|---|
| Scale factor EEPROM address | h2B6 |
| Measurement unit EEPROM address | h2B7 |
| Serial number (chip) EEPROM address range | h2E4‑h2E7 |
| Calibration changeability | Scale factor and measurement unit cannot be changed after calibration |
Set the EEPROM address to h2B6 using the set‑address command (0xFA) and then perform an I2C read to retrieve the scale factor word.
The chip serial number is stored in the EEPROM at addresses h2E4 (MSB) through h2E7 (LSB).
No, the measurement unit is written during calibration and cannot be changed later.
Bits encode dimension prefix, time base, volume/pressure unit and reserved fields as described in the measurement unit coding table.