Which controller to use?
in [Embedded]
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From: Fevric J. Glandules on 5 May 2010 04:41 Tim Wescott wrote: > If you want success, you MUST make sure that the hardware you specify > can do everything you ask of it. This is not a trivial task if you > don't want to way overdesign the processor. Something I really really should have said: "low-volume, high-margin". Not too fussed if we overspec the control module to the tune of a hundred dollars. > Talking to SD cards has a _much_ lighter footprint, although you still > have the connectors outdoors issue. Yes, this seems like a major issue to me. > You can buy Bluetooth modules; if you can find one that doesn't put too > much strain on the processor this may be way less expensive than USB, > and is contactless. Can you find a "contactless memory stick"?
From: Fevric J. Glandules on 5 May 2010 04:43 Frank-Christian Kr�gel wrote: > The processor core doesn't matter much. Choose your controller by the > built-in peripherials needed. Yup. I really want a drop-in box or board: http://tibbo.com/products/controllers/ds10xx/ds1004.html?gclid=CKCMtJTLuqECFdGX2AoddHvpBg http://www.tern.com/portal/content.asp?contentid=701 Thanks for your other tips.
From: Fevric J. Glandules on 5 May 2010 04:44 Paul Keinanen wrote: > You may have to derate the controller power consumption e.g. by > running it well below maximum frequency or reduce the output currents > for digital outputs etc. > > Weatherproofing will also make it harder to get rid off the > dissipated heat, thus the box inside temperature can be much higher > than the environment temperature. Good points Paul.
From: Fevric J. Glandules on 5 May 2010 04:57 D Yuniskis wrote: > Do you need these on the board? Or, hammer drivers? Or, > just a bunch of "digital outputs" that you will ultimately > interface to some OPTO-22's, etc.? Whatever is easiest! > From your description of the role of the tags, I assume your > settings only require a few KB, at most (e.g., 10 bytes per tag). > How big are these reports? Do they have to be created in ASCII I don't know yet, but "not very big". A few hundred K at most? > (i.e., how will they be *read* "elsewhere"? Could you put > a small application elsewhere to interpret raw data and > pretty-print it?) Yes. > What sort of display -- 7 segment, full graphic, color, etc.? Cheap! We may even use a buzzer to provide the necessary user feedback instead. > Can the tag itself contain the "amount of time to turn the relay > on for", etc.? Or, is it just a R/O tag that you treat as a > "unique identifier" used in an associative array paired with > the "on time data"? Unique ID. > shrug. Hard to be more specific without specifics. Indeed. As I said it's still a bit wooly but thanks to you and others here I have some pertinent questions for the client. If I've not answered some of your questions it's probably because at this time we simply don't know.
From: 1 Lucky Texan on 5 May 2010 08:52
On May 4, 3:01 pm, FJG <f...(a)invalid.invalid> wrote: > As a coder I've usually had custom hardware to work with and > the choice of architecture etc has been cost-driven and set > in stone long before I start trying to debug the board... > but I digress. > > I have a potential project coming up, where I may have > some influence on the hardware. The spec is of necessity > still slightly woolly, so my apologies for that in advance. > > The basics are > input - RFID tags, info probably read over RS-232 > output - solenoids / relays to turn a motor on > I/O - USB memory stick to upload new settings, download reports > control panel - three buttons and possibly a cheap LCD display > optional - WiFi interface > weatherproofed - will operate outdoors, off 12V DC > > ROM / RAM / CPU requirements are going to be modest by today's > standards. We're talking about, say, 200 RFID tags to recognise, > each of which has an individual setting for the amount of time > to turn the relay / solenoid on for. > > So any suggestions for a single board microcontroller that'd > provide the above at reasonable cost, with the minimum of hassle, > with a (preferably free) C toolchain? > > Personally I think the idea of a USB port on an outdoor piece > of equipment is a bit nuts, so any suggested alternatives? > Bluetooth? Though some of their boards are likely overkill, winsystems.com DOES have Zigbee on a board or 2(with usb, 422/485 and 232 of course). Plus, they have had a customer place their equipment in railyards to read rfid off of boxcars and other equipment run 'tolltags' on roadways. Do you have your own enclosure? |