SLAU723A October 2017 – October 2018 MSP432E401Y , MSP432E411Y
The TDI pin provides a stream of serial information to the IR chain and the DR chains. TDI is sampled on the rising edge of TCK and, depending on the current TAP state and the current instruction, may present this data to the proper shift register chain. Because the TDI pin is sampled on the rising edge of TCK, the IEEE Standard 1149.1 expects the value on TDI to change on the falling edge of TCK.
By default, the internal pullup resistor on the TDI pin is enabled after reset. Changes to the pullup resistor settings on GPIO Port C should ensure that the internal pullup resistor remains enabled on PC2/TDI; otherwise JTAG communication could be lost (see Section 17.5.15).