How to write/read strings EEPROM/LCD

[g-hoot]

Hello,
Im using a 16F648A and my program has a bunch of LCDOUT commands so that the user can select different settings. Well, I am adding new features, and am out of space. I saw Melanies post "Making Program Code Space your playground" for program space, but this chip won't allow that, so I'm thinking EEPROM is the Solution?

Here's part of the code I cut out to give a better idea of what I'm doing. Each time a certain button is pushed, it loops back through this part of the code:

Case 2
Refresh = Refresh + 1
IF Refresh = 9 Then Refresh = 1
ref:
Select Case Refresh
GoSub lcdone ' Position cursor at home
LCDOut "Refresh"
GoSub lcdsec
Case 1
LCDOut "None"
RefTime = 0
Case 2
LCDOut "30 Sec"
RefTime = 30 ' Move to 2nd line on LCD
Case 3
LCDOut "2.5 Min"
RefTime = 140
Case 4
LCDOut "7 Min"
RefTime = 400
Case 5
LCDOut "15 Min"
RefTime = 900
Case 6
LCDOut "30 Min"
RefTime = 1700
Case 7
LCDOut "1 Hour"
RefTime = 3500
Case 8
LCDOut "2 Hour"
RefTime = 7000

End Select
Pause 400

I have several of these menus throughout the program and the strings for most LCDOUT commands are different. I have played a little with EEPROM, but am not sure the easiest way to us it. Here's the only thing that I've gotten to work, but I'm afraid in may take more space (and a ton of work). I'm using values 0-15 for other stuff, so "A" is at 16. The code below displays "BAD" on the LCD.

EEPROM 0, [1,1,10,0,0,0,24,1,1,150,0,250,0,1,1,0,"A","B","C", "D","E","F","G","H","I","J","K","L","M"]

testmem VAR BYTE[8]

Read 17, testmem[0]
Read 16, testmem[1]
Read 19, testmem[2]
testmem[3] = " "
testmem[4] = " "
testmem[5] = " "
testmem[6] = " "
testmem[7] = " "

LCDOut STR testmem

I had to add all of the blank spaces in the last 5 spots of the array to keep "wierd" characters from being displayed. In the manual where it talks about strings in EEPROM, it says "No lenghth or terminator is automatically added", so I assume that's the reaon for the wierch characters, but don't really know how to fix it. I'm using the array of 8 since the LCD is a 2x8 display. Anyway, am I wasting my time here? Would I be better off just saying:

LCDOUT "BAD"

Sure could use some ideas on how to free up some space. Thanks,
Gary

[Archangel]

Greetings g-hoot,
I never tried this but here is my idea.
StringVar var byte

Stringvar = testmem[3]
gosub string

Stringvar = testmem[4]
gosub string

Stringvar = testmem[5]
gosub string

Stringvar = testmem[6]
gosub string

String:
LCDOUT stringvar
return

What I am thinking is the lcdout commands are using up your codespace, so put them into a loop and make the string a variable, give the variable the value you wish to display and then call the display subroutine. Also see select case instructions in the manual.
JS

[Archilochus]

Hi ghoot,
Not sure if it would save any code space overall, but you might want to look into the "LOOKUP" command too.

Also, in your code where you limit "Refresh" to 8...

Refresh = Refresh + 1
IF Refresh = 9 Then Refresh = 1

You might want to do this instead...

Refresh = Refresh + 1
IF Refresh > 8 Then Refresh = 1

That way if the Pic ever has some glitch and makes "Refresh" any value greater than 8, the code will revert back to "Refresh=1"

Arch

[mister_e]

Different ways... use an external EEPROM to store your strings and some variable values (reftime etc etc) Or work around something like
http://www.picbasic.co.uk/forum/show...bedded+strings

it's up to you!

[g-hoot]

Joe,
I got "rid" of all of the LCD out commands with a sub and sure thought that would do the trick, but my program only went from 3934 to 3931. Here's what I did:


IF Refresh > 8 Then Refresh = 1
ref:
Select Case Refresh
GoSub lcdone ' Position cursor at home
T[0]="R":T[1]="e":T[2]="f":T[3]="r":T[4]="e":T[5]="s":T[6]="h":T[7]=" "
GoSub LCDout1
GoSub lcdsec
Case 1
T[0]="N":T[1]="o":T[2]="n":T[3]="e":T[4]=" ":T[5]=" ":T[6]=" ":T[7]=" "
GoSub LCDout1
RefTime = 0
Case 2
T[0]="3":T[1]="0":T[2]=" ":T[3]="S":T[4]="e":T[5]="c":T[6]=" ":T[7]=" "
GoSub LCDout1
RefTime = 30

etc........

LCDout1:
LCDOut STR T
Return


What did you mean by "Also see select case instructions in the manual."...am I missing something there?

Arch,
I fixed the "IF Refresh > 8 " problem. Thanks for that. I've looked at the LOOKUP command, but really don't don't understand it. I guess if I set up the alphabet as constants, that won't use any space, but once I use lookup to read them into an array, woukldn't that take up the same space as above?

mister_e,
This board design has been done for a while, so I can't use external on this one, but if I do it on another design, when I retrieve the strings to go into the LCDOUT command, won't that put me in the same boat? As you can see, I'm quite a rookie at this. :-) I don't think I can do the embedded strings either since this chip won't let me use program space. "Flash Program Write" is disabled when I select that chip in the EPIC Programmer.
Gary

[mister_e]

Ah crap! So the RTFM of the day goes to me

Using an external EEPROM solve the problem, the only thing you have to keep in your PIC is the EEPROM start address of your string. From there, you just call and display routine.

Anyways, i'm pretty sure there's something to do around this without changing your actual stuff... let me sleep on this. If you want, you can post your whole code here or, if you can't for some privacy and/or commercial reason, send it on my e-mail.

[Archangel]

Joe,



What did you mean by "Also see select case instructions in the manual."...am I missing something there?

Dohe!
Well it's like this, these coke bottle thick glasses . . . I didn't see you had used select case already, Just ignorant of me, sorry.
JS
EDIT: You might check with Darrel, I think he has something that measures the code size for each bit of code, but understand this, my memory isn't worth much.

[g-hoot]

"the only thing you have to keep in your PIC is the EEPROM start address of your string"

Ahh, I think it's starting to sink in to my thick melon. What I was trying to do was set up the alphabet in upper and lower case, and numbers and a few other characters in eeprom, and then call each one individually. I noticed in many places that people were looping through like this:
for i = 0 to 7
read i, LCDtext(i)
next i

but that wouldn't work with the alphabet deal since I had to jump around to different, non-sequential eeprom locations.
So, what you are saying is that I would save each actual string in eeprom and then just give the loop the starting location of the string. I'm only using about 16 locations of eeprom right now, and this chip has 256, so that leaves me enough room for about thirty 8 character strings, so that should help a bunch. I'll give that a shot tonight.
Thanks all,
Gary

[mister_e]

You might check with Darrel, I think he has something that measures the code size for each bit of code, but understand this, my memory isn't worth much.

I think you talk about...

How much code would a code hog hog
http://www.picbasic.co.uk/forum/showthread.php?t=2418