SGP41-D-R4 datasheet(12/22 Pages) SENSIRION

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version 1.0 – December 2021

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4 Digital Interface Description

4.1 General Considerations

For detailed information about the I2C protocol itself and its detailed implementation, please, consult the document NXP I2C-bus

specification and user manual. All SGP41 commands consist of two bytes (16 bits). The commands must not be followed by a

CRC. Additionally, data sent to and returned from the sensor is transferred in packets of two bytes (16 bits) followed by a 1-byte

(8 bit) CRC.

4.2 I2C Address

The sensor’s I2C address is 89 (decimal; hex.: 0x59). The I2C header is formed by the I2C address followed by a read or write

bit.

4.3 I2C Voltage Levels

Input and output voltage levels are specified in section 6.1 of NXP I2C-bus specification and user manual. The sensor’s interface

is compatible with 1.7–3.6 V I2C bus voltage levels depending on the supply voltage level.

4.4 I2C Protocol Speed

The sensor supports I2C “standard-mode” and “fast-mode”, with a maximum clock frequency of 100 or 400 kHz, respectively.

4.5 I2C Sequences

The typical communication sequence between the I2C master (e.g., a microcontroller in a host device) and the sensor is

described as follows and visualized in Figure 15:

1.The sensor is powered up.

2.The I2C master periodically calls the measurement command and reads data in the following sequence:

a.I2C master sends a measurement command.

b.I2C master waits until the measurement is finished either by waiting for the maximum execution time or by waiting for the

expected duration and then poll data until the read header is acknowledged by the sensor (expected durations are listed

in Table 8).

c. I2C master reads out the measurement result.

Figure 15 Possible I2C command sequences for communicating with the SGP41. Dark areas indicate that the sensor controls the SDA (data)

line. First, the I2C master sends the write header writing a 16-bit command, potentially followed by two words of data with CRC bytes. For

reading the measured data, the I2C master sends the read header and receives one word of data with CRC byte in case of the built-in self-

test and in case of conditioning or two words with CRC bytes in case of measuring the raw signals of the two pixels. In case of reading out

the serial number of the sensor, the master receives three words with CRC bytes.

With the acknowledgement of the measurement command, the SGP41 starts measuring. When the measurement is in progress,

no communication with the sensor is possible and the sensor aborts the communication with a NACK condition. After the sensor

has completed the measurement, the master can read the measurement results by sending an I2C read header. The sensor will

acknowledge the reception of the read header and responds with data. The response data length is listed in Table 8 and is

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