Author: LinglingG_46 Version: **
What is the GPIO state during start up in PSoC® 4?
On reset or power-up, all GPIO pins start up in the high-impedance analog mode, that is, with the input buffer and output driver disabled. These GPIO pins remain in this mode until the reset in released; then the initial operating configuration of the associated registers of each GPIO pins in loaded during boot and take effect at that time. During runtime, GPIOs can be configured by writing to the associated registers.
Note: In PSoC 4000 parts, pin P1 is temporarily configures XRES during power-up until the device executes the start-up code. Do not pull this pin down during power-up as this keeps the device in reset. The reset provision via P1 is only for production test purpose and not intended for user applications.