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MPC8308 Hangs on Power up, Boots Normally when Manual Reset Applied.

Question asked by Jack Wallace on Apr 5, 2014
Latest reply on Apr 5, 2014 by alexander.yakovlev


I am debugging some problem boards that are behaving in a peculiar manner.  The design uses the MPC8308.  These boards are peculiar in that they hang upon power up but will boot normally after a manual reset is applied.  There are other builds of this design that boot fine at power up.  The two problem boards hang in the same place.  I have investigated the power sequencing (Core Voltage before I/O voltages, Looks good, Supply ramp time is 14ms, shortened it to 1.6ms no change), the reset logic (PORESET released 214ms after power-up and clocks have been running), I can power the board while holding the MPC8308 with a manual PORESET, wait minutes and release the manual PORESET signal and the board hangs in the same spot.  We are running U-BOOT with a Linux Kernel, but it is hanging somewhere in U-BOOT just after initializing the eTSECs. Both builds that hang, have the same processors and are as follows: [MPC8308VMAGD, 400/266 MHz, CTQLW1208, 00M17Y WDAJCTG]  There is a later revision processor, MPC8308VMAGDA.  But I'm finding it difficult to discover the differences in the Revisions. Thanks for any suggestions.