Dead Propeller

Tom Bampton

Hi,

Not really sure if there's much point in posting this, but figured I would post it anyway.

At some point while building a new board, I got myself confused and wired an RCA socket for TV out backwards. After hooking it up to a TV, the prop was brutally murdered. I swapped the prop one from a known-good board and all works fine now. The dead prop does not work in the old board.

Programming RAM and EEPROM both work, which suggests the internal oscillator is working fine. VGA however does not work, which suggests an external oscillator problem. I am guessing that it's the PLL mainly due to that being what died in the other forums posts relating to dead props.

I don't have the equipment to investigate this any further, so I am just going to stick a "DEAD" sticker on the prop and chalk it up to experience. It's the first IC I've killed for a good 10ish years, so I am long overdue a moment of stupidity [noparse]:)[/noparse]

T.

Paul Baker

Yes there is an issue with the PLL failing if seriously bad things are done. Typically this is cause by improperly wired inductive loads or ground loop issues. It's not that the PLL was designed improperly as some people have conjectured, it is that it is the most sensitive part and is the most suceptible component (akin to being a lightning rod). If we more robustly designed the PLL, very likely another subsystem would become the new lightning rod. We will be investigating different techniques to combat this in the new chips, but there are currently no plans for a redesign of the current chip (at least until we get some data back from our experiments).

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.

rjo_

Tom,

As a member of the Frequent Fryers Club, I would like to envite you to our next roast... to be held in conjunction with the release of PropII.

Rich