Two analog input problem on 16F877

[Pinocchio Faken]

Hi guys Good day~

I'm Pinocchio Faken, this is the first time I use the forum.

I'm new in GCbasic just a month, and not good in English either....(my mother tongue is Chinese)So I hope you forgive me to make some mistake....

I've using two LM35(temp sensor) to link on 16F877's PORTA.0 & PORTA.3 and display on 16x2 LCD.
I'm using ISIS simulator to check it. And it works with an error.

I've set the two temp sensor to 86℃ & 30℃.
Then save the converted analog port PORTA.0 & PORTA.3 data in string var cTemp1 & cTemp2.

PORTA.0 →cTemp1
PORTA.3 →cTemp2

And use cTemp0 & cTemp1 to display on LCD screen.

Print on LCD:
T1=cTemp0 r T2=cTemp1 r

The normal state may be T1=86r T2=30r. But the screen shows both 86 on it, here is the problem.

I think the problem is in ADCON0 register.
ADCON0 register is used to configure the analog input channel.
But it is Auto setted in the function ReadAD10().
So I don't know where the bug is.

Here's the ADCON register's datasheet.

===================Here is the code===================

;Chip Settings
#chip 16F877,4

;Defines (Constants)
#define LCD_IO 4
#define LCD_RS PORTB.0
#define LCD_NO_RW
#define LCD_Enable PORTB.1
#define LCD_DB4 PORTB.2
#define LCD_DB5 PORTB.3
#define LCD_DB6 PORTB.4
#define LCD_DB7 PORTB.5
#define AnalogA PORTA.0
#define AnalogB PORTA.3

;Variables
Dim cTemp1 As string
Dim cTemp2 As string

STARTUP
Do Forever

'Read Analog Input and use var to save it.
cTemp1 = ReadAD10(AnalogA)*49 / 100
cTemp2 = ReadAD10(AnalogB)*49 / 100

'Fill 16 Blank to Second line and move the cursor back.
Locate 1, 0
Print " "
Locate 1, 0

'Display two Temperature data in second line
Print "T1="
Print cTemp1
Print "r"
Locate 1, 8
Print "T2="
Print cTemp2
Print "r"
Wait 1000 ms
Loop

Sub STARTUP
'Set input
Dir PORTA.0 IN
Dir PORTE.0 IN

'Set ADCON1 to 10000010, direct PORTA0~5 to Analog input
Set ADCON1.ADFM 1
Set ADCON1.PCFG3 0
Set ADCON1.PCFG2 0
Set ADCON1.PCFG1 1
Set ADCON1.PCFG0 0

'Set LCDOUT pin
Dir PORTB b'00000000'
Wait 500 ms

'Test Display
Locate 0, 0
Print "Temp System"
Wait 500 ms
Locate 1, 0
Print "Good Day!"
Wait 500 ms
CLS

'Display title "Temperature" on first line
Locate 0, 0
Print "Temperature"
End Sub

===================End of the code===================

[Anobium]

Welcome Pinocchio to the forum.

I think, your issue is the incorrect use of the readadc10 command. I made the same error.

See http://gcbasic.sourceforge.net/help/readad10.htm You need to use the ANx not the port address. I hope this fixes your issue.

You code should read

'Read Analog Input and use var to save it.
cTemp1 = ReadAD10(AN0)*49 / 100
cTemp2 = ReadAD10(AN3)*49 / 100

[Pinocchio Faken]

I change it and get the same result.
I read the #define in gcbasic manual, it just used to define a word(like AN0 or Analog0 et al) to replace object or pin.
So I think that is not the problem on this case.
I guess the problem is on ADCON0's chennal select.
But I have no idea to on assembly code...

[Anonymous]

Hello,

Here's some code I wrote a year ago for a book I'm writing. I'm using a PIC16F88 and the similar LM34. Maybe this will give you an idea:

;Project 42
;A program to read the temperature using the LM34DZ
;and display it on an LCD in Fahrenheit.

;----- Configuration

#chip 16F88, 8              ;PIC16F88 running at 8 MHz
#config mclr=off            ;reset handled internally
#config osc=int             ;use internal clock

;----- Constants

#define LCD_IO      4       ;4-bit mode
#define LCD_RS      PortB.2 ;pin 8 is Register Select
#define LCD_Enable  PortB.3 ;pin 9 is Enable
#define LCD_DB4     PortB.4 ;DB4 on pin 10
#define LCD_DB5     PortB.5 ;DB5 on pin 11
#define LCD_DB6     PortB.6 ;DB6 on pin 12
#define LCD_DB7     PortB.7 ;DB7 on pin 13
#define LCD_NO_RW   1       ;ground RW line on LCD

;----- Variables

dim temp1, temp2 as word              

;----- Program

dir PortA in                ;only A.0 is used
dir PortB 0b00000011        ;top six bits are outputs

cls
print "Temperature:"        ;print this on top line

do
  temp2 = readAD10(AN0)     ;get temperature reading
  temp1 = 125 * temp2       ;now alter the scale.
  temp2 = temp1 / 256       ;quotient stored in temp2
  temp1 = temp1 % 256       ;remainder stored in temp1

  if temp1 > 127 then       ;is remainder past the midpoint?
    temp2 ++                ;if so, bump to the next degree
  end if

  locate 0,13               ;clear old value
  print "   "
  locate 0,13               ;print new value
  print temp2

  wait 1 S                  ;update once a second
loop

[Anobium]

Just checking. What version of the compiler are you using? The version is shown when you compile the code.

[Pinocchio Faken]

OK I see.
I haven't thought about different versions will make mistakes on compiling.
This is a way to solve the problem.
I'll try it.

[Anobium]

@Pinocchio

I just looked at your code. I do not think the code here will compile. Did you get any error messages when compiling?

You variables are incorrect. They should read.

;Variables
Dim cTemp1 As Word
Dim cTemp2 As Word

You code work in my simulator with these changes.

Anobium

Code I used.

  'Chip Settings
  #chip 16F877,4
  ;Defines (Constants)
  #define LCD_IO 4
  #define LCD_RS PORTB.0
  #define LCD_NO_RW
  #define LCD_Enable PORTB.1
  #define LCD_DB4 PORTB.2
  #define LCD_DB5 PORTB.3
  #define LCD_DB6 PORTB.4
  #define LCD_DB7 PORTB.5
  #define AnalogA PORTA.0
  #define AnalogB PORTA.3
  ;Variables
  Dim cTemp1 As Word
  Dim cTemp2 As Word
  STARTUP
  Do Forever
  'Read Analog Input and use var to save it.
  cTemp1 = ReadAD10(AN0)*49 / 100
  cTemp2 = ReadAD10(AN3)*49 / 100
  'Fill 16 Blank to Second line and move the cursor back.
  Locate 1, 0
  Print " "
  Locate 1, 0
  'Display two Temperature data in second line
  Print "T1="
  Print cTemp1
  Print "r"
  Locate 1, 8
  Print "T2="
  Print cTemp2
  Print "r"
  Wait 1000 ms
  Loop
  Sub STARTUP  
  'Set input
  Dir PORTA.0 IN
  Dir PORTE.0 IN

  Dir PORTB b'00000000'
  Wait 500 ms
  'Test Display
  Locate 0, 0
  Print "Temp System"
  Wait 500 ms
  Locate 1, 0
  Print "Good Day!"
  Wait 500 ms
  CLS
  'Display title "Temperature" on first line
  Locate 0, 0
  Print "Temperature"
  End Sub

[Pinocchio Faken]

I don't see any error messages during compile.
Whatever!
Thanks for testing Anobium ~
I'll try it tomorrow in my own PC.

[Pinocchio Faken]

I tried the code.
It has run with same problem using modified code.

I change the code like this:

=============================================================
;Variables
Dim cTemp1 As String
Dim cTemp2 As String

'Read Analog Input and use string var to save it.
cTemp1 = str(ReadAD10(AnalogA)* 49 / 100)
cTemp2 = str(ReadAD10(AnalogB)* 49 / 100)
=============================================================
I didn't change others.
Both I test the dim var with String and word had same display result.

And as Anobium said the compiler may be affect on these kind of problem.
I have checked my compiler's version.
GCGB ver0.9 , download on this page http://gcbasic.sourceforge.net/download.html
And update with the file "Update-GCGB.ZIP" 23/06/2012

I also use the IDE in the same download page "GCB@Syn.zip" to compile my code.
Unfortunately, I got the same error.

[Anobium]

Please try. This is the documented method to address the ports - but, this may work for you.

cTemp1 = str(ReadAD10(AN0) 49 / 100)
cTemp2 = str(ReadAD10(AN3) 49 / 100)

[Pinocchio Faken]

Thanks a lot Anobium, I solve the problem. But not on this way.

My own PC is working on Windows 7.
I want to preclude the effect on operating system.
So I try on my laptop in Windows XP environment.
And use GCB@Syn to compile the same code.
It just run in the right way!!
And I tried all of the code you ask me to change.
All of them can run correctly. (Include AN0, String, Word, AnalogA ... et al)
So I think the problem is on .NET framework or something Microsoft-based toolbox...

[Pinocchio Faken]

Today I try to change the code and do testing again on my own PC (Windows 7 32 bit).
I found a solution on this troble.
Move off the analog define code and use AN# to do coding.
It will run on correct way to do A2D.

============Original code start============

#define AnalogA PORTA.0 ←delete
#define AnalogB PORTA.3 ←delete

'Read Analog Input and use var to save it.
cTemp1 = ReadAD10(AnalogA)49 / 100
cTemp2 = ReadAD10(AnalogB)49 / 100

============Original code End ============

============Modified code start============

'deleted
'deleted

'Read Analog Input and use var to save it.
cTemp1 = ReadAD10(AN0) * 49 / 100
cTemp2 = ReadAD10(AN3) * 49 / 100

============Modified code End ============