How to use external clock(clk11,clk12) instead of internal BRG clock.

[jayanthkumarmj]

Hi,

Im writing firmware code for mpc8358, UCC is using as an USART for that I used BRG 8 and 9 clock it is working fine, but now I need to use external clock clk11 and clk12.

kindly help me out on this.

waiting for your reply

Thank you

[LPP · Accepted solution]

You can feed UCC UART direcly from external clocks (in asynchronous or synchronous modes).

For example, for synchronous UART on UCC1 or UCC3, CLK11 can be used as RX clock and clk12 as TX clock.

Clock routing: refer to QEIWRM Table 5-3

CMXUCR1[RU1CS] ='0111' //UCC1 receive clock is CLK11

CMXUCR1[TU1CS] ='1000' //UCC1 transmit clock is CLK12

I/O pins muxing, refer to MPC8360ERM Table 3-18

CLK11: pin PC10, CPPAR1C[SEL10]=01, CPDIR1C[DIR10]=10

CLK12: pin PC11, CPPAR1C[SEL11]=01, CPDIR1C[DIR11]=10