Serial LCD problems

crcordill

Hey guys I'm having trouble with my LCD screen. What I have going on here, is that I have 1 cog run a timer. I hold down a button on pin 21 and I count to see how long I hold it down. I can run it without the WriteLCD method, and it seems to work without a hitch. Any suggestions would be helpful. Thanks. Please note that I am new, and I have looked on the forum for help. Here is the code that I have written:

''CountLCD
'' Counts how long the button is pressed for and
'' displays it on the LCD
CON
LCD_Pin = 0 'The LCD is connected to pin A0.
LCD_Baud = 19_200 'Baud
LCD_Lines = 2 'The number of lines on this LCD

Off = 0
On = 1
OBJ
LCD: "Debug_lcd"
VAR
LONG stack[noparse][[/noparse]50]
BYTE TOG

PUB Main
TOG := 0
cognew(Countdown, @stack[noparse][[/noparse]0])
cognew(Button, @stack[noparse][[/noparse]10])
PUB Countdown
dira[noparse][[/noparse]1..5]~~
outa[noparse][[/noparse]1..5]~~
waitcnt(clkfreq*2 + cnt)
outa[noparse][[/noparse]1..5] := %111110
waitcnt(clkfreq*2 + cnt)
outa[noparse][[/noparse]1..5] := %111100
waitcnt(clkfreq*2 + cnt)
outa[noparse][[/noparse]1..5] := %111000
waitcnt(clkfreq*2 + cnt)
outa[noparse][[/noparse]1..5] := %110000
waitcnt(clkfreq*2 + cnt)
outa[noparse][[/noparse]1..5] := %100000
waitcnt(clkfreq*2 + cnt)
outa[noparse][[/noparse]1..5]~
TOG := 1

PUB Button | count1, count2, count
count1 := 0
count2 := 0
dira[noparse][[/noparse]21]~ 'Set pin 21 to input
dira[noparse][[/noparse]6]~~ 'Set pin 6 to output
outa[noparse][[/noparse]6]~
repeat while TOG == 0
repeat while ina[noparse][[/noparse]21] == 0
count1 := cnt
repeat while ina[noparse][[/noparse]21] == 1
outa[noparse][[/noparse]6]~~
outa[noparse][[/noparse]6]~
count2 := cnt
count := count2-count1
WriteLCD(count)

PRI WriteLCD(count)
repeat 10
!outa[noparse][[/noparse]6]
waitcnt(clkfreq/20 + cnt)

dira[noparse][[/noparse]LCD_Pin]~~
if LCD.Start(LCD_Pin, LCD_Baud, LCD_Lines)'Initialize the LCD object
LCD.Cursor(Off) 'Set cursor off
LCD.Cls 'Clear the LCD screen
LCD.Str(string("Button time")) 'Print string on LCD
LCD.Gotoxy(5, 1)
LCD.DecF(count, 8) 'Print count as a signed decimal

Chris Savage

Can you describe the issue you are having? Exactly what is happening with the LCD?

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Chris Savage
Parallax Tech Support

crcordill

It will run all the way through the light flashing. Then nothing happens. The LCD either stays blank, or shows what was previously on it. I never makes it through the first line of code. I've run another program, Debug_LCD_Test that runs perfectly (taking into account that I have a smaller LCD). It never has a problem, and its almost the exact same code. Also, did I say something to offend people? Nobody seems like they want to help.

Fred Hawkins

"Also, did I say something to offend people? Nobody seems like they want to help."

'my LCD screen' doesn't add enough information for me... What's the device exactly?

crcordill

In reference to the above comment, its a Parallax 2x16 Serial LCD (non-Backlit). Just the standard one off of the website.

MinimumWage

I'm no expert on all this, but from a quick look at the code you might want to declare two different stack variable arrays, and assign a different one for each COGNEW. Not allocating enough memory space can result in weird results at runtime.

Mike

crcordill

Yup, I tried adding more stack space to no avail.

MinimumWage

Maybe the attached file will help. I played around a bit with your code and added a couple of things. There was no _clkmode or _xinfreq statement set, and I think the various serial objects require the prop to be running at 80MHz for timing. If you don't explicitly define it the prop defaults to a slower internal clock. Also, I did set up new arrays for each of your cognew statements but I had to increase it to 50 longs before the LCD would update. (Change it back to 20 and try it yourself- the code compiles fine but nothing happens on the LCD.)

I didn't have time to test the button functions code, so I commented most of it out and just set up a counter to pass a number to WriteLCD. At least you know the LCD function is working, so you should be able to debug the rest.

NOTE: I'm testing this on a Spinstamp, so if you run this on a protoboard or demoboard you need to change the timing constants accordingly. I also changed the LCD pin to pin 12 since mine was already connected there.

Mike