The Functional requirements related to the proposed system
The functional requirements for a system describe what the system should do. These requirements depend on the type of device being developed, the expected users of the device, and the general approach taken by the organization when writing requirements. When expressed as user requirements, functional requirements are usually described in an abstract way that can be understood by system users.
However, more specific functional system requirements describe the device functions, its inputs and outputs, exceptions, etc., in detail. For example, here are examples of functional requirements for the reading device in Sinhala language for visually impaired people through the braille system, These requirements have a specific order to the priority, but for easy of explaining following order may bit different from the correct order.
[1] Turn on the Braille character display
[21] Turn the device off
When user select this option, Braille character display is turns on and resets display. Then alerts a welcome voice message and also after or before finished the reading book he can make the device off by using this option.
[2] Inserting a USB drive
[8] Safely remove USB drive
first of all assume that the USB drive contains e-book files to read. After turning on, a USB drive should insert in to the Braille character display. Name list of the books is displayed in the Braille character display one by one, when navigating in the name list. The user can stop reading further and can remove the USB drive.
[3] Navigates upwards in the book name list (when the is user at the beginning)
[6] Navigate upwards in the list
The user selects navigate upwards option when he is at the beginning of the list. The system generates an error sound. But the user at the middle of the list, he can go upwards in the list and the relevant name of the e-book is propagated in the Braille character display. Constraints that when displaying the name, if the character line space is not enough to represent the whole name, rest of the words are displayed in the next line.
[4] Navigate downwards in the books names list
[5] Navigate downwards list (user at the end of the list)
When the user navigates downwards in the list, the relevant name of the book is propagated in the Braille character display one by one. But the user selects this option when he is at the end of the list, the system generates an error sound.
[7] Selecting an e-book
[19] Selecting option
When the user selects a book, the system converts the text to relevant Braille character and the first line of characters are propagated in the Braille Character Display and also there is nothing happen selecting this option while reading the book
[9] Go to previous page (user is at the start of reading book)
[15] Go to previous page
First of all device looks for an available previous page. If a previous page available, device allow user to go to the previous page else the device generates an error sound
[10] Go to previous sentence (user is at the start of reading book)
[14] Go to previous sentence
This same as the function that I explain above
Device looks for an available previous sentence. If it is available user can move on to previous sentence else system generates error sound.
[12] Go to Next Sentence
[16] Go to Next Sentence(End of the book)
The next Sentence is propagated to the Braille character display and end of the book there are no any sentences to propagate to the Braille character display.
[13] Go to next page
[17] Go to Next page(End of the book)
By selecting this option the next page is propagated to the Braille character display. At the end of the book there are no any pages remain to propagate to the Braille character display and system make an error sound.
[11] Load next line of the sentence
[18] User at the end of the line (End of the book)
If the user selects the End of Line (EOL) sensor, the next line of characters is loaded to the Braille character display.at the end of the book. If the user selects the End of Line (EOL) sensor, device does not allow to move to next line or page.
[20] Go back to the names of the book list
After selecting ESC option, the name of the book is propagated back in the Braille character display.
These functional user requirements define specific facilities to be provided by the System. In principle, the functional requirements specification of a system should be both complete and consistent.
However, more specific functional system requirements describe the device functions, its inputs and outputs, exceptions, etc., in detail. For example, here are examples of functional requirements for the reading device in Sinhala language for visually impaired people through the braille system, These requirements have a specific order to the priority, but for easy of explaining following order may bit different from the correct order.
[1] Turn on the Braille character display
[21] Turn the device off
When user select this option, Braille character display is turns on and resets display. Then alerts a welcome voice message and also after or before finished the reading book he can make the device off by using this option.
[2] Inserting a USB drive
[8] Safely remove USB drive
first of all assume that the USB drive contains e-book files to read. After turning on, a USB drive should insert in to the Braille character display. Name list of the books is displayed in the Braille character display one by one, when navigating in the name list. The user can stop reading further and can remove the USB drive.
[3] Navigates upwards in the book name list (when the is user at the beginning)
[6] Navigate upwards in the list
The user selects navigate upwards option when he is at the beginning of the list. The system generates an error sound. But the user at the middle of the list, he can go upwards in the list and the relevant name of the e-book is propagated in the Braille character display. Constraints that when displaying the name, if the character line space is not enough to represent the whole name, rest of the words are displayed in the next line.
[4] Navigate downwards in the books names list
[5] Navigate downwards list (user at the end of the list)
When the user navigates downwards in the list, the relevant name of the book is propagated in the Braille character display one by one. But the user selects this option when he is at the end of the list, the system generates an error sound.
[7] Selecting an e-book
[19] Selecting option
When the user selects a book, the system converts the text to relevant Braille character and the first line of characters are propagated in the Braille Character Display and also there is nothing happen selecting this option while reading the book
[9] Go to previous page (user is at the start of reading book)
[15] Go to previous page
First of all device looks for an available previous page. If a previous page available, device allow user to go to the previous page else the device generates an error sound
[10] Go to previous sentence (user is at the start of reading book)
[14] Go to previous sentence
This same as the function that I explain above
Device looks for an available previous sentence. If it is available user can move on to previous sentence else system generates error sound.
[12] Go to Next Sentence
[16] Go to Next Sentence(End of the book)
The next Sentence is propagated to the Braille character display and end of the book there are no any sentences to propagate to the Braille character display.
[13] Go to next page
[17] Go to Next page(End of the book)
By selecting this option the next page is propagated to the Braille character display. At the end of the book there are no any pages remain to propagate to the Braille character display and system make an error sound.
[11] Load next line of the sentence
[18] User at the end of the line (End of the book)
If the user selects the End of Line (EOL) sensor, the next line of characters is loaded to the Braille character display.at the end of the book. If the user selects the End of Line (EOL) sensor, device does not allow to move to next line or page.
[20] Go back to the names of the book list
After selecting ESC option, the name of the book is propagated back in the Braille character display.
These functional user requirements define specific facilities to be provided by the System. In principle, the functional requirements specification of a system should be both complete and consistent.
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