X) User Interface Software Concept Selection



SOFTWARE

1) User Interface Software Concept Selection

Overview

Here are the concepts for the software selection. There are two realms to consider the software for. One is the software that will be used on the PC which the user uses to input coordinate data to the platform. The other is the software that is running on the platform that will receive the coordinate data and control the robot as it moves to the coordinates.

Screening Stage

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Scoring Stage

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Conclusion

For the software that the user will use to input coordinate data and that runs on the PC, LabView is the clear winner. LabView is a premier software package that is extremely fast to develop and easily maintainable. It is very easy to create elegant and highly functional graphical user interfaces using LabView. Visual Basic is a popular graphical programming language but out group does not have much experience with this platform and therefore it scores worse than LabView.

2) Platform Software Concept Selection

Overview

Screening Stage

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Scoring Stage

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Breakdown of Selection Criteria

Cost- This consists of total cost of the software package of each option.

Time requirement- This consists of the programming time required to get each option to work

Ease of Implementation- This is the difficulty in arriving at a software solution

Maintainability-This is how easy it will be to someone to modify the code at a later date

Team Experience-This rates the amount of experience on the team

Debug-This rates the quality of the debugging features available for the language

Number of Features-This rates how many tasks can be supported within the language

Resource Requirements- This consists of how much memory will be required to run each option.

Portability- This consists of how easy the program will be able to be interchanged between different operating systems.

Wow Factor- This refers to how impressive the user interface will be to the user.

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Figure 1.1 Example of possible platform software implementation (high level).*

*Note: This diagram is wholly abstract and implemented within the software run-time environment on the single board computer. There is nothing that can be physically touched in this diagram.

What is a ‘pipe’? (From )

I/O redirection isn't a command per sé, but I thought I should explain a little more about the '>' character in the previous example as well as elaborate a bit about input/output in a Linux or Unix environment.

Normally when a program runs, it takes it's input from stdin (standard input). Usually this is your keyboard. A programs output goes to stdout (standard output), and usually this is your terminal. In addition to standard out, there is also a seperate error output stream which by default also goes to your terminal.

In Unix or Linux, all devices are represented as files and most operations that you can do to an ordinary file you can also do with a device.

There are some operations that you can do on a file that you can't do on all devices. For example, you can seek to a location in a file, that is position to a specific location in the file for subsequent reading and writing. But you can't seek on a keyboard or printer.

Similarly, you can set the input modes, such as whether to take input a keystroke at a time or wait for an entire line, whether to echo keystrokes to the display or not, on a keyboard but you can't set the input modes on a file. What you can do on a given device is constrained by the physical capabilities of the device.

Every program that reads to or writes to a file first opens the file and obtains a file descriptor, an interger ID that is used to reference the open file for subsequent communications. When programs are invoked from the shell, they automatically have three descriptors open, '0' for stdin, '1' for stdout, and '2' for stderr.

Without a numerical argument, the redirect symbols refer to stdin '', with a numerical argument they can refer to other file descriptors such as stderr 2> for example.

For example:

$ cat afile > outfile 2> errfile

... says, read a file named 'afile', send it's output to 'outfile'. The program 'cat' if called with a single argument just outputs the contents of the file. If 'afile' did not exist; this would be an error, and the error message would be redirected into 'errfile'.

'>' is the output redirect character. It tells the shell to redirect the output of a command, in this case cat. If we did not include '> c' in this example, it would have merely printed the contents of 'a' and 'b' files instead of putting them in a file named 'c'.

It is also possible to redirect input from a file using the ' ................
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