NewbieL Help with keypad and LCD program 8051

[Jack M]

I am starting to learn C and am studying the lcd keypad program (project MC032) but I am not sure how to go about this.

I have a 20char x 2 line optrex character lcd

I have wired a 10 key keypad using the 3 col x 4 row kepad matrix as shown in the schematic for project MC032.

C2/R4 and C3/R4 are not used

I need to limit the range of inches between 5.00  max and 0.50 minimum; this is the length of my linear screw.

I want to display on the first line of the LCD [ Num of Inches:2.00 ] then move the cursor to the first digit
when C1/R2 (#3) is pressed I want to decrease the first digit by one until it reachs 0
when C2/R2 (#4) is pressed I want to increase the first digit by one until it
reachs 5 unless the 2nd and 3rd digit is greater than one. my limit is 5.00 inches

if C3/R1 (#2) is pressed move cursor to the right one digit unless there are no more digits
if C2/R1 (#1) is pressed move cursor to the left one digit unless there are no more digits

Which means that 2nd and 3rd digits may have different settings depending on  other digits setting.

when C3/R2 (#5) is pressed it takes all of the individual numbers, converts it to a single interger and stores it to a variable i.e.  “2.65”  or “4.73”

The second line on the LCD will display [ Num of Photos:030 ]

I would like to do the same thing that was done for the first line.

Range is 002 -250.

I am not sure as to how limit the ranges and change the inidiviual numbers

Your probably wondering what I am doing.    I am trying to build my wife automatic macro photograhy  lead screw.

She puts in the number of inches of travel and number of photos then the controller moves the camera to each step, a mini relay will activate
the remote shutter release.  She gets to decide the number of steps and distance.

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