ESPHome adds a shared driver for AS7341, AS7343 and TCS3448 spectral sensors, giving makers measurements of brightness, colour temperature and the light useful to plants. It also reports individual colour bands, an RGB colour value and how close a reading is to saturation.
Anton Viktorov combines the sensor support with calibration that makes readings at different exposures comparable. In his diffuse-daylight testing, the two tested sensors measured brightness within about 15% of an uncalibrated handheld light meter. Absolute accuracy depends on the optics and calibration of each installation.
Moving from the older AS7341 driver changes its raw counts because that driver read the two bytes in the wrong order. Existing calculations based on those counts need attention when changing to the new driver.