| ??? 10/17/06 22:17 Read: times |
#126615 - Wake up! Responding to: ???'s previous message |
Erik Malund said:
I don't know what it is that makes you insist that a newer MCU is "better" in any way, than an old, "steam-driven" MCU
1) a newer derivative is not (about to be) discontinued If you're only building ONE, then the ONE you already have won't be discontinued unless you lose it. 2) a newer derivative is cheaper There's no guarantee of that. That doesn't matter if you already have the one you're planning to use. 3) your design will have a longer lifetime If I like it, I'll buy spares while I can, for maintenance. Odds are, it will live until I lose it. 4) you are less likely to run out of steam Why would YOU worry about that? you have tons of money to waste on making new PCB's for at your boss'/clients' expense That is accusing me of not being a professional, I resent that. I do not waste money, be it mine or my clients. Are you sure? You apparently use pretty costly stuff without ever considering its cost-effectiveness and encourage everyone else to do the same. The guy who bought the eval kit that his instructor told him to use might find it difficult to justify buying a new $15 MCU just because Erik likes it. I have specifically made allowances for those forced to do so. (help them but make them aware to "go forth and sin no more") That's not how you usually frame it! He might find it costly to have a new board made. Where do you see me stating any such. WHO, but you, claim that buying a devboard means getting a board with a 8255. There are, actually, some devboard makers that have not been too lazy to update their designs. Anyone who's read your posts knows you'd never, Never, NEVER use an 8255 for anything, no matter how sensible it might seem, despite the fact that the specified MCU easily allows for its use.. 1) I know no case where it is 'sensible' How about when the boss tells you to do that? 2) should such a case come up, I would use it. Then you'd likely keep your job. anyone who's read your posts knows you'd never use any component that's been on the market for more than half a day. NOT TRUE, the litmus test is not 'age' but "is it replaced by something better" such as gaining 18 port pins by the replacement of the 'traditional' '51 by a RD2 or even a '668, not to mention an 8-porter such as the SILabs F120. Will it plug into the existing 44-pin PLCC socket? Remember, you're only building ONE, and it has to use THIS board. (Careful how you answer that!) However, you've completely overlooked the basic purpose of microcontrollers, namely to replace a lot of logic where it would have otherwise been required. Now you are completely off the rocker. Who, more than me, has hammered "If you use a '51 do control, if you want 'process' get another chip" If you don't have to do anything, why use anything at all? IF you do anything at all, e.g. serial-to-parallel conversion, AND two values and pass the result on, etc, that's processing. If you don't have to do that, then all you need is wire. Today, there are lots of applications into which one places a general-purpose board with an MCU and some peripheral hardware instead of a board of logic, in order to build one or two of something. That doesn't warrant a new PCB, and a new part, in high-density packaging, with enough I/O's to support your arguments, just won't fit into such an application. If you visit the SILabs forum, you will find legio users that do just that and (GASP) without an 8255. Erik PS you keep blasting me for making a list complete (the PSD chips) should I make an incomplete list, just because my recollection is the existence, not the website? Not for not making a list, but for not specifying what you're referring to. However, we've established that ST is making a few of these parts, albeit not just as port expanders, but as FLASH (too much) + RAM (too little) and I/O (enough, maybe, but probably not) parts that are not generally available and apparently on the decline. I don't deny that there are probably good reasons. For one thing, they don't work on existing boards, i.e. you can't readily put them on the expansion area of an existing COTS board because of their packaging. Aside from that, they only provide 27 bits of I/O yet cost nearly twice what an 8255 costs, AND you apparently can't buy them in lots of fewer than 25. RE |
