Addressing multiple capsense express devices on the same I2C bus

Question: How to address multiple Capsense Express devices on the same I2C bus ?

 

Answer:

By default the I2C address of capsense express capacitive controllers are all set to 0x00h. If customer board needs to have two capsense express parts then master should follow the below steps to avoid data corruption in I2C bus,


Step#1: Master puts CE#1 in reset mode by pulling XRES pin high
Step#2: Master sends CE#2 configuration file (generated by PSoC designer) over the I2C bus. Customer should select different address for CE#1 & CE#2 in PSoC designer to avoid address conflict.
Step#3: Master resets CE#2 (software reset or hardware reset)
Step#4: Master puts CE#2 in reset mode by pulling XRES pin high, this step is optional since after Step#3 CE#2 address will get updated from 0x00h to user configured value.
Step#5: Master sends CE#1 configuration file (generated by PSoC designer) over the I2C bus.
Step#5: Master resets CE#1 (software reset or hardware reset).

Note:
i)      CE#1 - refers to 'Capsense Express' device #1
ii)     CE#2 - refers to 'Capsense Express' device #2
iii)    For the above procedure to work, make sure that atleast one of the capsense express part (out of the two) on board have XRES pin bonded out.