Other Parts Discussed in Thread: AM3352
Hello, I am using AM3352 to design a product, and use a GPIO as input function to connect a keypad, the part of schematic like first picture. If push the keypad, the processor will be halted and voltage of IO pin will be pulled down from 3.3V to 1.9V, waveform show in the second picture. If remove the C1 capacitance, the failure disappears. I`ve tested three different GPIOs like: GPIO1_30\GPIO1_31\GPMC_A11, it`s same phenomenon for one another. I have also checked the official EVM schematic of TI, it show in the third picture. The different is additional resistance(2.2K ohm) as series connection into line to GND.
I thought it won`t cause processor down that if a normal IO pin is set input function, although connected the pin to GND direct. I am feeling it relate to inner structure of AM3352 IO gate, and hope any expert would explain it deeply, thanks.
