MPC5744P with 8MHz Oscillator , Aurora Interface

[larskrause]

Hello,

I have 8MHz Extal instead of 40MHz, for MPC5744P cut2 rev3.

I use PLL0 to generate 160MHz (MOTC) and 40MHz (feeding PLL1).

In PLL1 I can generate out of the 40MHz the Sys_clk = 200MHz. This is working, since I can output the 200MHz on the oscilloscope.

But it seems there is some problem with the Aurora interface. I cannot connect to the target with 8MHz and the described settings.

Whereas, when using a 40MHz Xtal which feeds both PLL0 & PLL1 (not the cascaded PLL configuration) I have no problems. (The visualisation tool which establishes the connection to the target is Vector VX1132 and the VX1452 POD for HSSL- high speed serial link via Aurora).

I wonder whether I configured everything correctly for the cascaded PLL setting, I also did only find example source using 40MHz Xtal.

--> !! I also use the xls you provide for clocking, but e.g. there is not the hint like in ref-man:

NOTE: In cascaded PLL configuration (PLL0 driving the reference clock for PLL1) the external power
down signal for PLL1 must be removed only when PLL0 has locked, PLL0SR[LOCK] = 1.

.. do you have example source for cascaded pll ?  

Thanks

Lars

[petervlna]

Hi,

I have tested it only on 40MHz XTAL.

Attached is example of cascaded PLLs.

PLL0 = 160MHz

PLL1 = 200 MHz

But there should be no issue also when you use 8MHz one.

Just follow the RM : 13.5.1.4 PLLDIG initialization information chapter.

Peter

PS: Have in mind that VCO must be in range 600 — 1250 MHz.