MCF52277 BOARD WON'T BOOT UP

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Hello guys, I found a very strange problem on our MCF52277 display board , there are some boards won't boot after power on , I also can't trig external reset in this state ,(may be 2 boards in 100), and  we measured the voltage and clock signal which both are normal .the difference is when the board didn't boot up the RSTOUT pin maintain low (graph b in the attachment file  yellow line is rst green line is RSTOUT), if the board boot up normally(graph a)  the RSTOUT goes high.     I check the reference manual  it says the RSTOUT goes high when the VDD reached a minimum acceptable voltage and PLL achieves phase lock. So I wonder if the PLL lost lock before reset sequence done? I can't confirm this reason. and don't know how to fix it...    There is a register that can trigger reset after PLL lost lock.  but I can't modify the value before cpu boot up.. @Hui_Ma      

[Hui_Ma]

Hi,

There is a PLL errata [SECF033: PLL Loss of Lock and Clock Jitter] at MCF5227x errata document.

This errata only affect the chip Rev. 1.1. 

Please refer below picture about chip mask set realted chip version:

Hui_Ma_0-1658537197045.png

When the PLL lost of lock and chip does not run out of reset phase, the RSTOUT is low means the chip still run in reset phase, which should be reasonable.

Please check the different behavior of external crystal of working board vs. issue board.

If possible, could you change the issue board with a new crystal and check if that could fix the issue board.

Wish it helps.

Mike