Once I have established what the software is to do I can worry about how to test it. For each of the actions above we could write a little test specification. Perhaps this is overkill for a simple job like this, in that I will know when the LCD works because I will see characters appear when I make it work properly, but for a larger program the test specification will be very important.
As I have already mentioned, you should never work on the basis that your test routine will involve just turning the system on to see what happens....
If you are working for a customer you should write a test specification even when the job is very simple. Think of it as a way of making sure you get paid, in that once your system meets the spec. you can down tools and demand some money!
For the LCD I have decided on the following test sequence:
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Start up the LCD (clear the screen and make the cursor appear)
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Clear the screen.
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Print the message "Hello World" on the top line
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Position the cursor at the middle of line 2 and print an 'X' character.
Testing has large consequences for everyone