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    BME680 Gas Reading Speed

    BME680 Gas Reading Speed

    Established Member


    - What is the fastest update rate for each of the 4 parameters (gas, temp, humidity, pressure) when using the BSEC and the BME680?

    - When NOT using the BSEC, what is the fastest update rate for the 4 sensors?

    - Can this update rate be sustained for long periods if power were not an issue. Page 24 of the datasheet seem to suggest that it is not sustainable (under Continuous).



    5 REPLIES 5

    Community Moderator
    Community Moderator

    @kevyk wrote:

    I am speaking about the second paramter passed in to:

    return_values_init err = bsec_iot_init(BME680_I2C_ADDR, BSEC_SAMPLE_RATE_LP, 0.0, bus_write, bus_read, sleep, state_load, config_load);

    If instead of BSEC_SAMPLE_RATE_LP you pass in 1.0 (or 0.999), no error is ever returned however if you pass in say a 0.5, this error is appropriately returned:

    BSEC_E_SU_SAMPLERATELIMITS = -12,   /*!< The sample_rate of the requested output (virtual) sensor passed to bsec_update_subscription() does not match with the sampling rate allowed for that sensor */

    If 1.0 is not allowed, it should probably also return an error. That said, page 24 of the data sheet does say that a 1Hz update rate is allowed however it seems to return values at a 0.5Hz rate.

    Oh, understood now, then you are correct, the library doesn't return any error as it matches the definitions of the Continuous mode, but this mode is not released as you pointed out because not qualified for longer operation.

    @kevyk wrote:

    But the important issue for my application is that I need a faster update rate for the IAQ. Since the BSEC does not yet allow for faster sample rates, and since it appears that I am able to get faster data back from the sensor directly without the use of BSEC, is the general code for the BSEC or equations used in the BSEC available so that I could derrive my own pseudo IAQ?

    A related question then is before the BSEC was avilable, how did users derrive anything useful from the gas resistance value (once they've calculated it) that they could use?

    As mentioned we are hoping to bring a new official mode to BSEC with a sampling rate similar to the Continuous mode, but we cannot share any confirmation or timeline yet. BSEC was always made available together with the BME680. If you are an experts with a deep understanding of this sensing technology, you may use the BME680 is raw data mode and derive your own pseudo IAQ from it, but otherwise since BSEC cannot be open you would need to use one of the officially supported modes.