16F88 ADC problem

[Darrel Taylor]

I'm trying to get a 16f88 to read a voltage and display it on a LCD. ...

The LCD is connected to the default connections on the 16f88, an LED connected to RB1, and a variable voltage to AN0.

The "Default" LCD pins have the data bus on PORTA<3:0>.

It will be difficult to also read an analog voltage on AN0 (PORTA.0)
<br>

[greensasquatch]

Thank you for pointing out what should have been very painfully obvious. I'll redo the code tonight and post the results.

[greensasquatch]

So one thing at a time, I want to get the LCD working again but on PortB. I've gone back to my code for the 16f627A and I want to get it working there before going back to the 16F88 and trying the ADC again.

I have used defines for LCDout so that I only use port B.

It compiles alright but when I run it on the PIC the LCD does not initialize. The light comes on, boxes are displayed (as the code used to do before initializing), the LED begins to toggle, but no change on the LCD.

The Code:

'************************************************* ***************
'* Name : LCDTest1.pbp *
'* Author : Greensasquatch *
'* Notice : Copyright (c) 2008 greensasquatch.ca *
'* : All Rights Reserved *
'* Date : 05/09/2008 *
'* Chip : PIC16F627A *
'* Version : 1.1 *
'* Notes : Send Hello World to a LCD on PORTB pins *
'* : blink a LED connected to RB6 as a status light *
'************************************************* ***************
'* PicBasicPro program to demonstrate *
'* operation of an LCD in 4-bit mode. *
'************************************************* ***************
'*
'* Connections are as follows:
'*
'* N/C -01-|####|-18- N/C
'* N/C -02-|####|-17- N/C
'* N/C -03-|####|-16- N/C
'* N/C -04-|####|-15- N/C
'* Gnd -05-|####|-14- V+
'* LCD Pin DB4 on RB0 -06-|####|-13- RB7, N/C
'* LCD Pin DB5 on RB1 -07-|####|-12- RB6, to red LED
'* LCD Pin DB6 on RB2 -08-|####|-11- RB5, E on LCD
'* LCD Pin DB7 on RB3 -09-|####|-10- RB4, RS on LCD
'*
'************************************************* ***************

INCLUDE "MODEDEFS.BAS"

@ DEVICE pic16F627A, INTRC_OSC_NOCLKOUT, MCLR_OFF

DEFINE LCD_DREG PORTB ' LCD data port
DEFINE LCD_DBIT 0 ' LCD data starting pin, RB0-RB3
DEFINE LCD_RSREG PORTB ' LCD register select port
DEFINE LCD_RSBIT 4 ' LCD "RS" register select pin
DEFINE LCD_EREG PORTB ' LCD enable port
DEFINE LCD_EBIT 5 ' LCD "E" enable pin
DEFINE LCD_BITS 4 ' LCD data bus size
DEFINE LCD_LINES 2 ' number of lines on the LCD
DEFINE LCD_COMMANDUS 1500 ' command delay in us
DEFINE LCD_DATAUS 44 ' data delay in us


'LED Connected to PortB.0 to circuit is doing something
LED var PORTB.6

CMCON = 7 'Turn off comparators
Pause 2000 ' Wait for LCD to startup

loop: toggle LED
Lcdout $fe, 1 ' Clear LCD screen
Pause 500 ' Wait .5 second
Lcdout "Greensasquatch" ' Display Greensasquatch on 1st line
Pause 500 ' Wait .5 second
toggle LED
Lcdout $fe,$c0,"Hello" ' move cursor to 2nd line, display Hello
Pause 1000 ' Wait 1 second
toggle LED
Lcdout $fe,$c0,"World" ' move cursor to 2nd line, display World
Pause 1000 ' Wait 1 second
toggle LED
Goto loop ' Do it forever

[mackrackit]

LCD4 TO RB4
LCD6 TO RB5
LCD11 TO RB0
LCD12 TO RB1
LCD13 TO RB2
LCD14 TO RB3

I think it is wierd wrong

[Melanie]

In no particular order...

1. Turn down the Contrast...

2. Double-Check your LCD wiring

3. Some LCD's need DB0-DB3 grounded to work in 4-Bit Mode.

4. Some LCD's need their R/W pin Grounded

5. Increase LCD_COMMANDUS to 2000 and LCD_DATAUS to 50 (values which seem to work with most LCD's).

6. Check your code is the same as that which you have posted... if you have a typo in the LCD DEFINEs it will not throw up an Error at compile time.

[Archangel]

Everything Melanie said, and bypass the LCD's power leads with an .01 &micro;F cap between them. I ran into a Display which wouldn't work otherwise, and it was attached to a 16F628A.

[greensasquatch]

Thanks for the help first of all.

I've rewritten the code and connections as per the example in the picbasic pro manual.

Works great on the 16F627A, now to port it over to the 16F88.

I'll post the results when it's done.

'************************************************* ***************
'* Name : LCDTest1.pbp *
'* Author : Greensasquatch *
'* Notice : Copyright (c) 2008 greensasquatch.ca *
'* : All Rights Reserved *
'* Date : 05/09/2008 *
'* Chip : PIC16F627A *
'* Version : 1.1 *
'* Notes : Send Hello World to a LCD on PORTB pins *
'* : blink a LED connected to RB6 as a status light *
'************************************************* ***************
'* PicBasicPro program to demonstrate *
'* operation of an LCD in 4-bit mode. *
'************************************************* ***************
'*
'* Connections are as follows:
'*
'* N/C -01-|####|-18- N/C
'* N/C -02-|####|-17- N/C
'* N/C -03-|####|-16- N/C
'* N/C -04-|####|-15- N/C
'* Gnd -05-|####|-14- V+
'* E on LCD on RB0 -06-|####|-13- RB7, LCD Pin DB7
'* RS on LCD on RB1 -07-|####|-12- RB6, LCD Pin DB6
'* N/C -08-|####|-11- RB5, LCD Pin DB5
'* red LED on RB3 -09-|####|-10- RB4, LCD Pin DB4
'*
'************************************************* ***************

INCLUDE "MODEDEFS.BAS"

@ DEVICE pic16F627A, INTRC_OSC_NOCLKOUT, MCLR_OFF

' Set LCD Data port
DEFINE LCD_DREG PORTB
' Set starting Data bit (0 or 4) if 4-bit bus
DEFINE LCD_DBIT 4
' Set LCD Register Select port
DEFINE LCD_RSREG PORTB
' Set LCD Register Select bit
DEFINE LCD_RSBIT 1
' Set LCD Enable port
DEFINE LCD_EREG PORTB
' Set LCD Enable bit
DEFINE LCD_EBIT 0
' Set LCD bus size (4 or 8 bits)
DEFINE LCD_BITS 4
' Set number of lines on LCD
DEFINE LCD_LINES 2
' Set command delay time in us
DEFINE LCD_COMMANDUS 2000
' Set data delay time in us
DEFINE LCD_DATAUS 50


'LED Connected to PortB.3 to circuit is doing something
LED var PORTB.3
output PORTB.3

CMCON = 7 'Turn off comparators
Pause 2000 ' Wait for LCD to startup

loop: toggle LED
Lcdout $fe, 1 ' Clear LCD screen
Pause 500 ' Wait .5 second
Lcdout "Greensasquatch" ' Display Greensasquatch on 1st line
Pause 500 ' Wait .5 second
toggle LED
Lcdout $fe,$c0,"Hello" ' move cursor to 2nd line, display Hello
Pause 1000 ' Wait 1 second
toggle LED
Lcdout $fe,$c0,"World" ' move cursor to 2nd line, display World
Pause 1000 ' Wait 1 second
toggle LED
Goto loop ' Do it forever

[greensasquatch]

So I've now got a new problem, can you tell I'm a noob yet?

I've created a program now to make sure the 16F88 is working ok.

I load the program in to the pic, compile, burn and it works. LED flashes away merrily.

My problem now is that I can no longer reprogram the chip.

If I connect my JDM programmer to the serial port I can detect the programmer with PICPgm and if i then insert the chip I can detect it. BUT when I try to burn the new hex file it immediately says No chip found, and then no programmer found.

I'm wondering if it has something to do with using the RA6 and RA7 pins that are normally OSC pins. It almost seems like the programmer is fine until the PIC gets power and starts doing it's blink code. (just guessing, I'm really new at this and grasping at straws).

Any suggestions?

the code in case that helps:

'************************************************* ***************
'* Name : 88Blinker.pbp *
'* Author : Greensasquatch *
'* Notice : Copyright (c) 2008 *
'* : All Rights Reserved *
'* Chip : PIC16F88 *
'* Date : 06/09/2008 *
'* Version : 1.0 *
'* Notes : To set up the most basic settings to flash *
'* : an LED on a PORTB pin using only the internal *
'* : oscillator and MCLR turned off. *
'* : *
'************************************************* ***************
'*
'* Connections are as follows:
'*
'* RA2 -01-|######|-18- RA1
'* RA3 -02-|######|-17- RA0
'* RA4 -03-|######|-16- RA7 to LED
'* RA5 -04-|######|-15- RA6 to LED
'* Gnd -05-|######|-14- V++
'* RB0 -06-|######|-13- RB7
'* RB1 -07-|######|-12- RB6
'* RB2 -08-|######|-11- RB5
'* RB3 -09-|######|-10- RB4
'*
'************************************************* ***************

OSCCON = $60 'set int osc to 4mhz
ANSEL = 0 'ALL DIGITAL
CMCON = 7 'COMPARATORS OFF

TRISA = %00000000 'all output
TRISB = %00000000 'all output
PORTA = 0 'all porta low

@ DEVICE MCLR_OFF, INTRC_OSC, WDT_ON, LVP_OFF, BOD_OFF, PWRT_ON, PROTECT_ON
Pause 100 'wait to start

START:
High PORTA.6 'LED's on
High PORTA.7
Pause 1000
Low PORTA.6 'LED's off
Low PORTA.7
Pause 1000
GoTo START 'repeat