The LPC11C24 user program can be run at the beginning, but after a few months of testing, serveral chips enter the ISP abnormally, and then each time after power-on, they still enter the ISP mode. Only by erasing the chip program and reprogramming can it return to normal. I have detected that the ISP pin and power pin using a oscilloscope and when LPC11C24 is power on, the ISP pin is high level. It seems that it is not a hardware problem, so I suspect it is a software problem. Is there another way to enter ISP mode?
I attach the flowchart of LPC11U24 after Reset, when the LPC11U2x check whether the user code in flash is invalid, if the user code is invalid, the LPC11U2x will enter CAN bootloader or UART bootloader stage. So If your user code is incorrect, your phenomenon appears, pls check your user code.
Hope it can help you