Question: How is the CRC calculation done for Capsense express devices?
The ‘w A0 03’ command is used to write the new power up default settings to the Capsense controller. This command is to be followed by 123 bytes of data according to the POR Default Data Structure table. The 123rd byte is the CRC byte, which is calculated as the XOR of the first 122 data bytes. If the CRC check fails or an incomplete block is sent, the data will not be saved to the flash. Also, note that these 122 bytes of data will be stored from register address 0x04 and NOT from 0x00. More details about this can be found in the Command code section of the Register Reference Manual of CY8C201xx.