Interesting result on a 16F688 with ADC and LCD

Ive got some code I converted from a 18F4550 thermostat, want to use it on a 16F688, on running the RA4 port never goes high, and the LCD displays a block on row1 about location 14 on a 4x20 LCD. adjusting the pot on RA0 does nothing, ive tried messing with ADCON0 & 1, and ANSEL, but im doing something wrong.
MCP9700A on RA1
POT on RA0
RA4 has LED

Code:

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include "ADC_Default.bas"
DEFINE LCD_DREG PORTC  ' LCD Data bits on PORTC
DEFINE LCD_DBIT 2      ' PORTC starting address
DEFINE LCD_RSREG PORTC  ' LCD RS bit on PORTC
DEFINE LCD_RSBIT 0      ' LCD RS bit address
DEFINE LCD_EREG PORTC  ' LCD E bit on PORTC
DEFINE LCD_EBIT 1      ' LCD E bit address
DEFINE LCD_BITS 4      ' LCD in 4-bit mode
DEFINE LCD_LINES 4      ' LCD has 4 rows
ANSEL = %00000011
TRISA = %00000011
TRISC = 0 ' PORTC is output
 
LCDOUT $FE, 1 ' Clear LCD
PAUSE 500 ' Wait 0.5sec for LCD to initialize
SETT Var Word ' A/D converter result in 10bit
READT var word
AGAIN:
ADCIN 0, READT ' Read Channel 0 data
ADCIN 1, SETT ' Read Channel 0 data
ReadT = ReadT - 6500
SETT = SETT / 1024 'Output = 0 - 63
readT = ((((readT / 10) * 9) / 5) / 13) + 32 'Convert ANA0 to Farent.
setT = sett + 40 ' Temp Range will be 40 - 103
LCDOUT $FE, 2
LCDOUT $FE, $80
LCDOUT "Set Temp = ", DEC setT , $DF , "F    "
LCDOUT $FE, $C0
LCDOUT "Temp = ", DEC READT , $DF , "F    "
if SETT < (readt - 1) then PORTA.4 = 0
if sett > (readt + 1) then PORTA.4 = 1
pause 100
GOTO AGAIN ' Repeat
END

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Add 1K pull up resistor.

Hey Chris, Read the data sheet.... RA4 is open collector only when used as output..... Read the data sheet... It's your friend....

Hi Dave,
That was actually my initial thought as well but what I did was what you suggest (but perhaps didn't do ?) and read the datasheet before posting - which resulted in me not posting that response ;-)
There's no mentioning of RA4 being open drain on the 16F688 as is the case on some other devices - at least not what I could find.

/Henrik.

Yep I looked at it last night. I might need to add a resistor. On page 33 though it says it has weak internal pullups unless its an output pin. However that doesnt solve the LCD issue?
I tried removeing all the ADC and output pin code, and just leave it barebones with the LCD code and LCD still doesnt work, weird.

I am not sure what it is as the code is pretty simple.

Code:

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DEFINE LCD_DREG PORTC  ' LCD Data bits on PORTD
DEFINE LCD_DBIT 2      ' PORTD starting address
DEFINE LCD_RSREG PORTC  ' LCD RS bit on PORTD
DEFINE LCD_RSBIT 0      ' LCD RS bit address
DEFINE LCD_EREG PORTC  ' LCD E bit on PORTD
DEFINE LCD_EBIT 1      ' LCD E bit address
DEFINE LCD_BITS 4      ' LCD in 4-bit mode
DEFINE LCD_LINES 4      ' LCD has 4 rows

'TRISA = %00000011
TRISC = 0 ' PORTC is output
 
LCDOUT $FE, 1 ' Clear LCD
PAUSE 500 ' Wait 0.5sec for LCD to initialize

AGAIN:
LCDOUT $FE, 2
LCDOUT $FE, $80
LCDOUT "Set Temp = "
LCDOUT $FE, $C0
LCDOUT "Temp = "
pause 100
GOTO AGAIN ' Repeat

END

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Problem is its a removable PIC, LCD is tied to board with a premade cable so I cant change pins from LCD to PORTC

Henrik, I saw the chart on page

You removed ADC code, , but is ADC enabled on PortC for this PIC?

Robert

dang, I forgot C is adc ports too. Ive got an appointment I cant miss. Ill be back in a few hours. what command is it to turn adc off on portc. oh and since these are 6 bit registers do I use %000000 or %00000000 ? when doing settings?

PIC - LCD Pins
C0 - 4
C1 - 6
C3-6 - 11-14

Datasheet tells you what register to set.

I'd use 8 bits, no surprises.

Robert

Quote:

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Originally Posted by wdmagic

PIC - LCD Pins
C0 - 4
C1 - 6
C3-6 - 11-14

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Start pin is 2 or 3?

Code:

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DEFINE LCD_DREG PORTC  ' LCD Data bits on PORTC
DEFINE LCD_DBIT 2      ' PORTC starting address
DEFINE LCD_RSREG PORTC  ' LCD RS bit on PORTC
DEFINE LCD_RSBIT 0      ' LCD RS bit address
DEFINE LCD_EREG PORTC  ' LCD E bit on PORTC
DEFINE LCD_EBIT 1      ' LCD E bit address

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Sorry I was in a hurry to leave, starting bit is 2.

(C2-5 - 11-14) corrected

Quote:

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Originally Posted by wdmagic

Code:

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i
DEFINE LCD_DREG PORTC  ' LCD Data bits on PORTC
DEFINE LCD_DBIT 2      ' PORTC starting address

---

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The DBIT might be your problem - It has to be either 0 or 4 - you have to have your data lines as pins 0-3 or 4-7.

From the manual:

"If an 8-bit bus is used, all 8 bits must be on one port. If a 4-bit bus is used,
the top 4 LCD data bits must be connected to either the bottom 4 or top 4 bits of
one port. Enable and Register Select may be connected to any port pin. R/W may
be tied to ground if the LCDIN command is not used."

Ahhhh. ok, well dang, these are hardwired, I will have to move pins in the plug...
I figured thats why we could define a starting address was it started out on the one stated and counted up from there.

thanks andywpg

OK I now have something on LCD but its jibberish. I moved chip and lcd to breadboard for time being, PORTC 0-3 is now starting bits, RS is C.4 and E is C.5, nothing else is hooked up except LCD. I will need to turn on ADC for PORTA 0 & 1 after LCD starts working.

heres the code, notes are beside respective lines

Code:

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DEFINE LCD_DREG PORTC  ' LCD Data bits on PORTD
DEFINE LCD_DBIT 0      ' PORTD starting address
DEFINE LCD_RSREG PORTC  ' LCD RS bit on PORTD
DEFINE LCD_RSBIT 4      ' LCD RS bit address
DEFINE LCD_EREG PORTC  ' LCD E bit on PORTD
DEFINE LCD_EBIT 5      ' LCD E bit address
DEFINE LCD_BITS 4      ' LCD in 4-bit mode
DEFINE LCD_LINES 4      ' LCD has 4 rows
ADCON0 = 0 ' Tried it with and without this line
ANSEL = 0 ' Tried it with and without this line
TRISA = %00000011 ' Left this cause it shouldnt hurt LCD
TRISC = %00000000
 
LCDOUT $FE, 1 ' Clear LCD
PAUSE 500 ' Wait 0.5sec for LCD to initialize

AGAIN:
LCDOUT $FE, 2
LCDOUT $FE, $80
LCDOUT "This is a Test"
pause 1000
GOTO AGAIN ' Repeat

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Theres not much here to go wrong, anyone see anything?

Pause 1000 before 1st LCDOUT to start.

Quote:

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Originally Posted by wdmagic

OK I now have something on LCD but its jibberish. I moved chip and lcd to breadboard for time being, PORTC 0-3 is now starting bits, RS is C.4 and E is C.5, nothing else is hooked up except LCD. I will need to turn on ADC for PORTA 0 & 1 after LCD starts working.

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I had trouble without the following two defines (after the ones you already have):

Code:

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' Set command delay time in us
DEFINE LCD_COMMANDUS 1500
' Set data delay time in us
DEFINE LCD_DATAUS 44

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Then try this:

Code:

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PAUSE 500 ' Wait 0.5sec for LCD to initialize (May need to be one second, depends on your LCD)
DO
    LCDOUT $FE, 1, "This is a Test"
    Pause 1000
    LCDOUT $FE, 1 'clear the screen
    Pause 250 'wait 1/4 second
Loop

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No reason the above shouldn't work. Good luck

Quote:

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Originally Posted by wdmagic

OK I now have something on LCD but its jibberish. I moved chip and lcd to breadboard for time being, PORTC 0-3 is now starting bits, RS is C.4 and E is C.5, nothing else is hooked up except LCD. I will need to turn on ADC for PORTA 0 & 1 after LCD starts working.

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This may sound like a dumb question, but it IS a Hitachi 44780-comapatable display, right?

Just a thought......

Agg i posted a reply but it didnt take.

Yes Demon, that was the problem, I copied and pasted backwards, I changed the pins in the plug so it does work now on the premade board. a second problem I found was the premade board had a 7805 on it and I had tied the input of that to 5volts, it barely lit the screen and did not turn on the PIC, been stressing alot here lately, lots going on. but I have learned a ton this week. so the thermostat works, thanks everyone

yes andywpg, it is, I posted earlier but aprently the page didnt save it. its working now.