Multi RH/T Sensors w/ Same I2C Address

by <a href=""><font color="#000000"><font size="2">Genius Employee</font></font> </a> Daniel_H on ‎09-28-2016 05:31 PM


More than one RHT sensor is needed on a single I2C bus, however the I2C addresses are the same. How can two or more RHT sensors be used on the same I2C bus?


The RHT sensors do not have a programmable I2C address. Using a multiplexer and a device select line, multiple RHT sensors can use the same I2C bus. A single NMOS is placed on the SDA line with the drain on the host side and the source on the slave side. 10k pull-up resistors should be placed on both side of the NMOS. The MCU can control the SDA line by the device select.

by <a href=""><font color="#000000"><font size="2">Legend</font></font> </a> erikm
on ‎09-29-2016 10:22 AM

the above would, probably, work if the sensors are close; however having humidity sensors close does not seem likely.

I'd use the NXP I²C bus drivers/expanders such as PCA9507 - PCA9511 which improves the drive