SPRUJ53B April 2024 – September 2024 TMS320F28P550SJ , TMS320F28P559SJ-Q1
It is sometimes necessary to observe a clock directly for debug and testing purposes. The external clock output (XCLKOUT) feature supports this by connecting a clock to an external pin, which can be GPIO16, GPIO18, or GPIO71. GPIO16 has digital input and output functionality; so, to use it for monitoring XCLKOUT, the register GPAAMSEL should be set to 0. The available clock sources are PLLSYSCLK, PLLRAWCLK, SYSCLK, INTOSC1, INTOSC2, and XTAL.
To use XCLKOUT, first select the clock source using the CLKSRCCTL3 register. Next, select the desired output divider using the XCLKOUTDIVSEL register. Finally, connect GPIO16 or GPIO18 to mux channel 11 using the GPIO configuration registers.