Question: What is the maximum frequency that the CPU has to be for updating the I²C configuration registers.
Response: Only for the CY27x43 Silicon Rev A family of PSoC, the I2C_CFG register should be written with a maximum CPU frequency of 6MHz, and the I2C_SCR and I2C_MSCR registers should be written with a maximum frequency of 12MHz. For all other parts the above registers can be written with a CPU frequency of 24MHz. View the errata for die revision A of the CY8C27x43 device family at the following link: www.cypress.com/
If you are using a CY27x43 device with A as suffix, and if the CPU is operating at more than 6MHz, set the CUP_Clock_Speed parameter to “Above 6MHz”. The user module API will automatically insert code to throttle down the CPU speed before writing to the I2C_CFG register and restore the CPU speed after the write.
For all other devices this parameter should be set as “NOT CY8C27xA”.