menu system for LCD

[mesuty]

Hi friends;

I inspected the existing codes in the forum. My problem is to implement a menu system on a 2 line LCD. I have 4 buttons on circuit. By pressing two predefined buttons , the menu must appear. Menu has nearly 50 sub items in 4 sub groups. Most of the sub items deals with entering an float number through those 4 keys.

any kind of idea / help is appreciated.
Note : I inspected the function pointer based LCD algorithm , though could not apply to the problem.

[Neutone]

I like the simple method. Use the up down keys to select menu items. and the left right keys to increment or decrement. The trick is to inc/dec on a fixed time interval as the key is held down and increase the amount of the inc/dec while the key is pressed. Use one line to display the paramater name and the other paramater value. While this does mean scrolling through all the menu items you dont need to adjust its very simple and eazy to understand. It's also simple to explane to a new user where sub-menus are more dificult.

[Salenko]

[Ttelmah]

[Salenko]

hi,

thanks would be light to express my gratitude Mr Ttelmah, in two words : great person you are.

[Ttelmah]

You are missing the point about the note about the pins.
If you are using the standard pin defines, you need to use the CCS input instructions, not just defines for the pin numbers.
You could (for instance), do this:

[Salenko]

hi Ttelmah, thank you for answering me again,

I've made the following changements/corrections:

[crystal_lattice]

i've just presented my project yesterday (after completing a 3hour examination... and more than a month's worth of agonising documentation...) and was thinking to post my version of a LCD menu system in the code section in the near future.

I used the 16F886 as the touch key pad interface and this communicates with a 18LF4620 which is running the LCD menu. The keypad only had 4 buttons, UP,DOWN, ENTER and ESCAPE.

I did not have to enter any values but it enabled me to execute various functions like a calibration sequence and it also enables the user to adjust the date/time of the RTC using the UP/DOWN arrows. The whole menu was designed around a switch statement "state machine" and contained several sub menus.

During the next few days/week(s) i will try and strip it down and include a useful demo which i will post in the code section. It is not the most elegant menu system, but i gets the job done and is very simple to maintain.

[Salenko]

[Ttelmah]

As a comment 'back' to the question about interrupt time, I'm just letting the timer 'free run'.
Timers interrupt whenever they 'wrap' at the end of their count, back to zero. You can set a timer 'to' a value, to accelerate this, but unless you 'need' an exact time interval, you can just use the ntural wrap.
So, in the example, the timer is a 16bit timer (wraps every 65536 counts), fed off the prescaler of /8, which counts in Fosc/4 intervals. So the timer will interrupt every:

(4000000)/(4*8*65536)times per second

1.907times per second. Just over half a second intervals.
In fact, setting timers 'to' values, is always dangerous. The problem is that if the timer is being fed from a clock faster than perhaps a few dozen instruction times, there is always the potential for the clock to have already counted some cycles, before you reach the interrupt routine. Hence timings _will_ be inaccurate. Alternative is to read the timer, and add an offset to the value. Better, but still loses any counts that happen between the read, and the write. Also, on most timers, the prescaler is reset, when it's value is written, leading to another error...

Generally then, I'll always let timers free run, or use the timer2, which on the bigger PICs, has a hardware reset.

Best Wishes

[soulraven]

i have a problem with the code.....

[colesha]