Check out the below forum thread on bootloader for PSoC3. PSoC5 also supports the I2C bootloader. USB support is not yet available. http://www.cypress.com/forums/...readid=9746&forumid=1 However, there is an errata for PSoC5 bootloader. The PSoC5 bootloader only works at 400KHz I2C clock. It does not work at 50KHz and 100KHz clock speeds.