Because the nTRST and XRES are different. The XRES's function is to reset our chip. But the nTRST is to reset the standard JTAG tool. So if you want to use the reset mode, you must connect with XRES. But the nTRST is optional.
I am a beginner and I have the JTAG Segger , can I used it to programming the PSoC1 ?
when have photo to communication is good
Welcome in the forum, but there is a PSoC1 forum where you should ask that question, here you are in PSoC5.