How does the ISP code (USB interface) provided by Nuvoton determine whether an ISP update procedure is required after bo

[a_ziliu]

The ISP code (USB interface) provided by Nuvoton can refer to the logic of an I/O pin to determine whether an ISP update is required through hardware.

Developers generally leave an updated path on the product. However, whether an ISP update is required will be determined by software or hardware.
(1) Hardware determination: It uses the extra I/O pin, through high logic and low logic as the reference, to determine whether to perform an ISP update after booting. The advantage is that it takes almost no time to determine, and the disadvantage is that an I/O pin will be occupied.
(2) Software determination: The device first identifies and communicates with the PC via USB and determines if an ISP update is required. The advantage is that no additional hardware costs are required, and the disadvantage is that USB identification will take a while.

Usually, when USB is used as the interface for ISP update, hardware determination will be used because software determination takes longer (a few seconds) to recognize and communicate between USB and PC, resulting in poor user experience.

The latest version of NuMicro ISP programming tool and user manual from Nuvoton can be found at:
http://www.nuvoton.com/hq/support/tool- ... _locale=en