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Closed 10 years ago.
In my studies I have to write meter-bus (m-bus) protocol/functions in VHDL. and I have no idea from which point should I start. I read a little bit of http://www.m-bus.com/mbusdoc/default.php but were is a lot of information. Probably some one of you know the right functions list how should it work, or maybe some one have the example, or information how I should do it?
Thanks for your time.
I'd say start from the bottom.
1: Find the necessary transceiver chip (a TSS721 chip according to the physical layer documentation), and get it hooked up to an FPGA. You can probably do a loopback with it, and just try sending and receiving data from the same FPGA.
Interfacing to it seems to be done through a UART, so you can either write one yourself, or use one of the many UART implementations available (if you are using Xilinx Spartan-series or similar, have a look at the PicoBlaze UART implementation).
2: Once the physical layer is working (either as loopback on a single FPGA, or between two FPGAs), carry on with the next layer (the Datalink-layer) and get that working. I can highly recommend familiarizing yourself with a good simulator, which will allow you to test out the layers one by one, instead of having to rely on in-target tests in the FPGA.
3: Proceed to the next layers (Application and Network), until you're done.
For reference, I built something similar during my master thesis - a custom-made FPGA-based network, using Toslink transceivers. The project can be found here, and the code here - if you're interested in the full thesis, I can probably dig up the pdf's somewhere...
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Closed 9 years ago.
So far in my use of objective c and cocoa, I have made some simple OSX apps that make use of some of the basic apple UI elements such as NSButton, NSTextFeild, NSView, etc. However, now I find that I'm wanting to add parts to my programs that don't fit so squarely within the given UI elements. ie. in a program I'm writing now, I want to create a checklist in which users can enter new elements, check off elements to delete them, etc. all with a custom UI. My problem right now is that I don't even know where to start looking for the information I need to learn how to create more advanced things like this, or what to search for to start finding information. Could anyone set me on the right track as to what information I should be looking for and where I can go to find it? Thanks.
You'll probably want to look at Cocos2d or even OpenGL. I'm guessing though that this may be overkill for your solution. You might also be able to override or extend some of the base UI elements.
If you're new to Objective-C and Mac OS programming, I would recommend taking it a bit slower with this. Often we developers dream up huge complex interfaces when really, just a basic, stock interface would work just fine for our users.
For your first release, keep it simple and just ship some code in short time. Then work with your users and see how they really want to work with your app and go from there.
Good luck!
db
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Closed 10 years ago.
I was wondering if folks use VHDL/FPGAs in scientific computing.
An example scenario that I was thinking off was say:
Construct an arbitrary precision floating point adder
Configure an FPGA board to then add such numbers
So I was looking for references (example code) where VHDL/FPGAs have been used in scientific computing.
Thanks in advance.
There are several vendors who build heterogeneous computing systems using FPGAs. I doubt you'll find complete source code for such systems.
SRC Computing
Convey Computer
Mitrionics. A reseller of other systems.
Novo-G. An academic project.
Look into radio astronomy. With arrays such as the VLA and ALMA, the massively parallel correlator is the part that could be considered most important. These typically use FPGAs but could use custom-designed chips for extreme performance at higher cost.
Some fine reading:
https://science.nrao.edu/facilities/cdl/digital-signal-processing
http://web.njit.edu/~gary/728/Lecture8.html
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Closed 10 years ago.
I need to test drive Naïve string search algorithm.
http://en.wikipedia.org/wiki/String_searching_algorithm
Can someone shed some light on how I could approach the issue.
should my tests only be testing outside behaviour? (i.e. the pattern occuring indexes irrespective of the algorithm used? )
Or should I be algorithm specific and test drive algorithm specific implementations?
Or should I be algorithm specific and test drive algorithm specific implementations?
This largely depends on how your class will be used. Testing public contract is usually the way to go (and it's fairly easy to write decent tests for that), so unless your clients can somehow use implementation details knowledge, I'd stick to that.
Note that having specific algorithm on paper could help pinpointing few basic tests, without writing strictly implementation related tests, like:
invalid input (empty strings, nulls)
input being too large/too small (like, pattern exceeding searched string length - what do you do then?)
valid input, yet matching nothing
This should give you basic entry point for more implementation specific testing. Keep in mind that utilizing data driven testing can help you avoid the need of having implementation level knowledge altogether, and with large enough data set might be just enough to verify algorithm correctness aswell.
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Closed 11 years ago.
My multicore machine is receiving packets and distributes them evenly (sort-of round robin) among its cores. Each core should decide whether to let the packet pass or drop it, depending solely on its origin address.
I need to find lock-less algorithm and data structure to allow this. Can you help?
If you are happy to use Java, or look at the design of Java source, you could chose a random key and then retrieve a queue from http://docs.oracle.com/javase/1.5.0/docs/api/java/util/concurrent/ConcurrentHashMap.html. Given the queue, you could add the packet to it without blocking if it was a http://docs.oracle.com/javase/1.5.0/docs/api/java/util/concurrent/ConcurrentLinkedQueue.html
Much of java.util.concurrent is due to Doug Lea, who has information on it at http://gee.cs.oswego.edu/dl/concurrency-interest/index.html.
Possibly overkill for your particular problem, but might satisfy a general request for info on data structures in this area.
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Closed 11 years ago.
I need to use a wireless barcode scanner to scan a barcode and send the data to the application located on a computer and then the computer processes the data given.
but I don't know how should I make my application listening for the barcode info over WIFI,
how can I do that?
and can barcode scanners send data to a web form automatically? (GET)
and another question , do you think QR-codes are suitable for warehouse management?
thank you
That really, really depends on the interface that your scanner provides. As long as you are both connected to the same WiFi network, you can probably just access it via its IP. But how you specifically connect will vary between scanners.
About the web form, I doubt it will support that. But again it depends on the scanner. You'll most likely have some method of it PUSHing data.
I think the question you need to ask about the tracking isn't specifically about QR Codes, but rather whether a 2D bar code is what you need at all. Warehouses are increasingly moving over to RFID for internal tracking, and with RFID labels dropping in price they're viable too. If you want to stick to an ink-based approach, what advantage will a 2D bar code have over a basic 1D one in your scenario?
The latter is much easier to deal with, yet does somewhat rely on orientation unless you have a multi-directional scanner. In that case, you'll probably find it more reliable; it's going to be using a laser as opposed to having to essentially photograph and decode the 2D code.