Author Topic: Why yes ST, slapping an interface all over the place is exactly what I wanted.  (Read 1819 times)

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Offline daqq

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OK, I have to ask, would it make baby Jesus cry if interfaces were together on packages? It's better these days I guess than say, their STR9x series, but still, why is it done? What is the problem in keeping an interface together-ish?
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Offline uncle_bob

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That is seriously messed up ...


Offline dannyf

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Because st iss secretely run by a bunch of guys from nxp.

Offline NANDBlog

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You havent tried routing the memory interface yet. That is where the fun part starts. Like it is on all 4 sides, not in order...
While it is really upsetting, and I had my share of ST's pinout, I understand why this happens. First, on different packages, you want to keep some of the pins at a fixed location, and put some extra pins. This means those extra pins go in the middle. Also, keep in mind, that they are basically have limits, what they can do when packaging the device. You have pads on the die, and you have less than a mm to put those bond wires. There must be some rules that they need to follow.
And why did they do the pads that way? Well BGA of course. For every QFP package we buy for our stuff, there will be 100 sold in BGA, and CSP size sold for the consumer market, going into something very small.

Offline digsys

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And sometimes, cases where I have personally run across (TI), they make changes to suit ultra-high volume customers ie car makers in the past,
mobile phones etc I've even had beta MPUs that had pilot production devices with bits missing or other changes because a large customer decided
he didn't want them. It can just be a financial decision sometimes.
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Offline bktemp

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You havent tried routing the memory interface yet. That is where the fun part starts. Like it is on all 4 sides, not in order...
It can even be worse:
32bit SDRAM + 24bit TFT controller + SD card + external USB phy.
Most peripherals can select from 2-3 different IO pins, but if you use many peripherals, you have less choice and then the layout gets realy ugly.

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