For all PSoC1 devices (CY8C20xxx, CY8C21xxx, CY8C22xxx, CY8C24xxx, CY8C27xxx, CY8C29xxx) it is highly recommended to follow the below procedure to enable I2C block. This is to avoid ongoing I2C traffic in the bus to disrupt PSoC I2C block state machines.
Procedure to enable I2C block,
Step1: Disable I2C block (by clearing the ‘Enable’ bit in the I2C_CFG register)
Step1: Put I2C SDA & I2C SCL pins to ‘HI-Z Analog’ drive mode
Step2: Enable I2C block (set the ‘Enable’ bit in the I2C_CFG register)
Step3: Give delay equal to 4 I2C sample clock periods
Step4: Restore I2C SDA & I2C SCL pin drive modes back to OD-LOW