1. How do I check the boot image size in the cypress EZ USB suite?
>> You can check the size of the image (.img) file which will be stored in the SPI flash. For example, if the firmware image size (boot image) is 150 KB. The user data can be written from the SPI flash location after 150 KB.
Then, is there any problem with using parts other than that size area?
>> Please refer to this KBA Selection of SPI Flash Compatible with FX3/CX3/FX3S/FX2G2/SD3/SD2 and the Recommended Cypress SPI Flash Parts - KBA221833 for selecting SPI flash compatible with FX3
2. Can I use this example?
>> Yes, SPI DMA mode example can be used to read/write from/to SPI flash using Control Center application
3. Is there any problem if I receive'output.image' through communication after booting USB and write it back to the boot area?
>> I didn't understand the question. Please restate the question.