Hi Barry, You can connect a maximum of 2 BME388 per i2c bus. The maximum amount of sensors depends on how many i2c buses you have in your system (most hosts that more than 1 i2c bus, there are also i2c bus multiplexers ICs). For SPI, there is not limit to the number of devices. Apart from SCK, MOSI and MOSI, one need 1 chip select GPIO pin for each slave device. the maximum number of slaves is therefore the maximum number of GPIO pins available on your host. There again, there are a variety of I/O expanders that can greatly increase the number of GPIOs for Chip Select pins. o_o
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