Hi there,
Looking through the datasheet of IWR6843 and the mmWave SDK GPIO driver, and I found some divergent information. In GPIO driver of mmWave SDK, in the file pinmux_xwr68xx.h, at the line 120, the pin E13 is defined as GPIO_3, SPIA_CLK or DSS_UART_TX, but in datasheet, at page 15, the pin E13 is defined as GPIO_30, SPIA_CLK or DSS_UART_TX.
Link of datasheet: www.google.com/url
Link of SDK: software-dl.ti.com/.../index_FDS.html