LCD will not start

[btaylor]

Problem solved.

I originally had my TRIS statements immediately following the port definitions. By making the first line of my code a PAUSE 2500 statement followed by the TRIS etc, the system now works.

It seems the LCD wants to see floating drive for something more than one second before it is happy. With this approach I can eliminate all my initialise code and just rely on LCDOUT $FE, $01 to somehow do it for me.

The following code now works on both slow start and fast start power supplies as well as a direct MCLR.

define osc 20
define loader_used 1
Define LCD_DREG PORTD
Define LCD_DBIT 0
Define LCD_RSREG PORTD
Define LCD_RSBIT 5
Define LCD_EREG PORTD
Define LCD_EBIT 4
DEFINE LCD_LINES 2
DEFINE LCD_BITS 4
DEFINE LCD_RWREG PORTD 'LCD read/write port
DEFINE LCD_RWBIT 6 'LCD read/write bit
DEFINE LCD_COMMANDUS 2000 'Command delay time in us
DEFINE LCD_DATAUS 100 'Data delay time in us
define char_pacing 200
DEFINE SHIFT_PAUSEUS 100

@ Device pic16F877A, HS_OSC, BOD_ON, LVP_OFF, PWRT_ON, WDT_ON, PROTECT_OFF
'@__config_HS_OSC &_BOD_OFF &_PWRT_ON &_WDT_ON &_PROTECT_OFF &_LVP_OFF

'**************** hardware definition **************
'PortA
Function var porta.0 'pin 2 analog from 12 position switch IN
RunStop var porta.1 ' SWp6 to 877p3 Front panel toggle IN
Enter var porta.2 ' SWp4 to 877p4 Selects current value IN
Up var porta.3 ' SWp2 to 877p5 Advances selection IN
AutoMan var porta.4 ' SWp7 to 877p6 Local/Remote control IN
Down var porta.5 ' SWp3 to 877p7 Reduces selection IN
'TRISA = %00011111
'CMCON = %00000111 ' comparators disabled
'ADCON0 = %11000000 ' int RC clock, ADC disabled
'ADCON1 = %11001110 ' port 0 analog, all others digital

'PortB
GMData var portb.0 'bidirecional data to/from Master Controller
GMStrobe1 var portb.1 'signals MC that GM needs attention
GMStrobe2 var portb.2 'signals GM that MC has data
GMSpare var portb.3 'a PCB trace between PeeWee50 pin 9 and 877p36
LED2 var portb.4 'front panel LED2
N2 var portb.5 'Nitrogen solenoid
SClk var portb.6 'Intersema SClk OUT to MS5534 & 5535
DIn var portb.7 'Intersems Data In OUT from 877a to MS5534 & 5535

'TRISB = %00001111
'PortB = %00000000

'PortC
CO2 var portc.0 'CO2 solenoid
O2 var portc.1 'O2 solenoid
MClk var portc.2 'MClk to Intersema PWM2 32678 Hz OUT to MS5534/5
Vent var portc.3 'Vent/dump solenoid
Delvry var portc.4 'delivery solenoid controls final delivery
SpareSol var portc.5 'spare solenoid OUT
TxD var portc.6 'Boot loader and RS232 OUT
RxD var portc.7 'Boot & RS232 IN
'TRISC = %10000000
'PortC = %00000000

'PortD
DB4 var portd.0 'Data bit 4 to LCD
DB5 var portd.1 'Data bit 5 to LCD
DB6 var portd.2 'Data bit 6 to LCD
DB7 var portd.3 'Data bit 7 to LCD
LCDEnable var portd.4 'LCD ENABLE line OUT to LCD
RegSel var portd.5 'LCD Register Select OUT to LCD
ReadWrite var portd.6 'LCD Read/Write line OUT to LCD
LED1 var portd.7 'Front Panel LED1
'TRISD = %00000000
''PortD = %00110000
'PortD = %00000000

'PortE
ClrEntry var porte.0 'SWp5 to 877p8 Clears entry on front panel??? IN
Dout1 var porte.1 'Input from 14 bar Intersema
Dout2 var porte.2 'Input from 1 bar Intersema
'TRISE = %11111111
'PortE = %00000000

'******************** Variable assignments ************************
'OPTION_REG = %10001111 ' no pullups, prescaler to WDT /128

A var byte ' General purpose Variable
B var byte ' General purpose Variable
C var byte ' General purpose Variable
I var byte
J var byte
K var byte
FuncSel var byte ' Switch position after decoding ADC value
ADCval var word
LoopCtr var byte
U var word
V var word
W var word
X var word
Y var word
Z var word
RunFlag var bit
C1 var word ' Pressure sensitivity
C2 var word ' Pressure Offset
C3 var word ' Temp Coef of pressure sensitivity
C4 var word ' Temp Coef of Pressure Offset
C5 var word ' Reference temperature
C6 var word ' Temp coef of Temp reading
D1 var word ' raw word from 5535
D2 var word ' raw word from 5535
W1 var word ' coefficient from 5535
W2 var word ' coefficient from 5535
W3 var word ' coefficient from 5535
W4 var word ' coefficient from 5535
dT var word ' intermediate calc value
UT1 var word ' Calibration temperature
Temp var word ' Sensor temperature
Tempnegflag var bit ' set if temperature is below zero C
Press var word ' Pressure
Offset var word '
Sens var word '


pause 2500 '
TRISA = %00011111
CMCON = %00000111 ' comparators disabled
ADCON0 = %11000000 ' int RC clock, ADC disabled
ADCON1 = %11001110 ' port 0 analog, all others digital
TRISB = %00001111
PortB = %00000000
TRISC = %10000000
PortC = %00000000
TRISD = %00000000
PortD = %00000000
TRISE = %11111111
PortE = %00000000


Loop:
lcdout $FE, $01
LCDOUT "Hello "
pause 500
lcdout $FE, $01, $FE, $C0
lcdout "World"
pause 500
goto loop

end


thanks to all who helped.

Cheers
Brian

[mister_e]

<img src="http://img8.picsplace.to/img8/22/Thumbs-up.gif">

[JohnPaul]

Hello, everyone.

I am new to this forum. I am so happy to see so many people helping out others. I wish I could be of help myself in the future.

I have been tracking problems in HD44780. I think this could be the closest problem solved that is relevant to my problem.

I have two HD44780 that I am currently getting to work. One is a 16x2 and another 20x4. I am using Pic Basic Pro & PIC16F627A. I pick this chip because I would like to simplify without the External Osc components. I am currently using a solderless breadboard.

Currently,
for the 16x2, I got 16 blocks on first line and blank on 2nd line.
for the 20x4, I am getting 20 blocks of 1st & 3rd lines, rest are blank.



So far, my code is

' HD44780 LCD MODULE
' Pin 1: VSS 0V(Ground)
' Pin 2: VDD Power Supply for logic
' Pin 3: V0 Power Supply for LCD Driver (5k Potentiometer for Contrast)
' Pin 4: RS Data / Instruction register select (10k Resistor)
' Pin 5: R/W Read/Write select
' Pin 6: E Read/Write enable strobe
' Pin 11-14: DB0-7 Data bus (LSB)
' Pin 15: LED Backlight (5.0v)
' Pin 16: LED Backlight (0v)
'
' PIC16F627A
' Pin 1: RA2 LCD DB6
' Pin 2: RA3 LCD DB7
' Pin 3: RA4 LCD RS (10k Voltage Pullup to +5v)
' Pin 5: VSS Ground
' Pin 9: RB3 LCD E
' Pin 14: VDD
' Pin 17: RA0 LCD DB4
' Pin 18: RA1 LCD DB5
'
' LCD Definition
DEFINE LCD_DREG PORTA ' Set LCD Data port
DEFINE LCD_DBIT 0 ' Set starting Data bit (0 or 4) if 4-bit bus
DEFINE LCD_RSREG PORTB ' Set LCD Register Select port
DEFINE LCD_RSBIT 4 ' Set LCD Register Select bit
DEFINE LCD_EREG PORTB ' Set LCD Enable port
DEFINE LCD_EBIT 3 ' Set LCD Enable bit
DEFINE LCD_BITS 4 ' Set LCD bus size (4 or 8 bits)
DEFINE LCD_LINES 2 ' Set number of lines on LCD
' DEFINE LCD_LINES 4 ' Set number of lines on LCD
DEFINE LCD_COMMANDUS 2000 ' Set command delay time in us
DEFINE LCD_DATAUS 50 ' Set data delay time in us

CMCON = 7 ' RA0-RA3 are digital I/O
TRISA = 0 ' PORT A is output
TRISB = 0 ' PORT B is output


RPT:
LCDOUT $FE,1 ' Clear LCD
LCDOUT $FE, $0C 'Cursor off
LCDOUT $FE, $0F ' Blinking cursor on
PAUSE 500 ' Wait 0.5 second for LCD to startup

' For 16x2 LCD
LCDOUT $FE,2, "Hello." ' Display 1st Line
LCDOUT $FE,$C0, "World." ' Display 2nd Line
' For 20x4 LCD
' LCDOUT $FE,2, "Hello." ' Display 1st Line
' LCDOUT $FE,$C0, "World." ' Display 2nd Line
' LCDOUT $FE,$94, "Line 3" ' Display 3rd Line
' LCDOUT $FE,$D4, "Line 4" ' Display 4th Line

PAUSE 10000 ' Wait 10 second

GOTO RPT ' Repeat

END ' End of program


I think based on code below. It appear that I am missing

define osc 20
define loader_used 1
@ Device pic16F877A, HS_OSC, BOD_ON, LVP_OFF, PWRT_ON, WDT_ON, PROTECT_OFF

for 16F627, what should my parameters be?
define osc 4 ? for pic16f627a
What is the usage for all these statements? Are they all required?
Can someone kindly explain? And show me where these material (an perhaps more) are documented?

Also, do I still need the following three PBP statements. Are they redundant with the DEFINE statements?
CMCON = 7 ' RA0-RA3 are digital I/O
TRISA = 0 ' PORT A is output
TRISB = 0 ' PORT B is output

What is the best way to test if my internal OSC function is working?

Since I am so new to all the elements, can someone tell me where how to pin down my LCD problem(s). Any help would be greatly appreciated.



Hello, everyone.

After I posted, I just added following statements to my code. Still no help.

define osc 4 ' Internal OSC 4 MHZ
define loader_used 1 ' ?
@ Device pic16F627A, HS_OSC, BOD_ON, LVP_OFF, PWRT_ON, WDT_ON, PROTECT_OFF


I am also new to both pic chip and LCD module. I have used voltmeter to check the voltages at each point. How do I conduct proper hardware check. I have been through many times on regarding the pin / wiring connection. How do I know if my chip is defective? How do I know if my LCD is defective? Thank you for reading.

John Paul
Michigan

Problem solved.

I originally had my TRIS statements immediately following the port definitions. By making the first line of my code a PAUSE 2500 statement followed by the TRIS etc, the system now works.

It seems the LCD wants to see floating drive for something more than one second before it is happy. With this approach I can eliminate all my initialise code and just rely on LCDOUT $FE, $01 to somehow do it for me.

The following code now works on both slow start and fast start power supplies as well as a direct MCLR.

define osc 20
define loader_used 1
Define LCD_DREG PORTD
Define LCD_DBIT 0
Define LCD_RSREG PORTD
Define LCD_RSBIT 5
Define LCD_EREG PORTD
Define LCD_EBIT 4
DEFINE LCD_LINES 2
DEFINE LCD_BITS 4
DEFINE LCD_RWREG PORTD 'LCD read/write port
DEFINE LCD_RWBIT 6 'LCD read/write bit
DEFINE LCD_COMMANDUS 2000 'Command delay time in us
DEFINE LCD_DATAUS 100 'Data delay time in us
define char_pacing 200
DEFINE SHIFT_PAUSEUS 100

@ Device pic16F877A, HS_OSC, BOD_ON, LVP_OFF, PWRT_ON, WDT_ON, PROTECT_OFF
'@__config_HS_OSC &_BOD_OFF &_PWRT_ON &_WDT_ON &_PROTECT_OFF &_LVP_OFF

[skimask]

Add the
PAUSE 500
BEFORE you send ANYTHING out to the LCD...
And try PAUSE 2000 and work your way down to a managable value.

[JohnPaul]

Hi, skimask.

Thank you for the reply.

I added PAUSE 2000 before CMCON=7 statement.

On my 20x4, I still get 20 blocks on lines 1 & 3.. and rest are blanks.


Regards,
John Paul

[skimask]

Hi, skimask.
Thank you for the reply.
I added PAUSE 2000 before CMCON=7 statement.
On my 20x4, I still get 20 blocks on lines 1 & 3.. and rest are blanks.
Regards,
John Paul

Hook up an LED to a spare pin, and rewrite the program to blink it once per second along with running your LCD. That should tell you that the program is running in the first place.
Note: I ALWAYS use a 'heartbeat' LED in my projects, doesn't matter what it is, or how I tie it into the main program, so long as I know how it's supposed to be blinking, whether I tie it into an interrupt, or just part of the main loop or whatever...doesn't really matter. And I usually don't remove the 'heartbeat' LED until I'm almost done, or I need that particular pin.

[Archangel]

' HD44780 LCD MODULE
' Pin 1: VSS 0V(Ground)
' Pin 2: VDD Power Supply for logic
' Pin 3: V0 Power Supply for LCD Driver (5k Potentiometer for Contrast)
' Pin 4: RS Data / Instruction register select (10k Resistor)
' Pin 5: R/W Read/Write select
' Pin 6: E Read/Write enable strobe
' Pin 11-14: DB0-7 Data bus (LSB)
' Pin 15: LED Backlight (5.0v)
' Pin 16: LED Backlight (0v)
'
' PIC16F627A
' Pin 1: RA2 LCD DB6
' Pin 2: RA3 LCD DB7
' Pin 3: RA4 LCD RS (10k Voltage Pullup to +5v)
' Pin 5: VSS Ground
' Pin 9: RB3 LCD E
' Pin 14: VDD
' Pin 17: RA0 LCD DB4
' Pin 18: RA1 LCD DB5
'
' LCD Definition
DEFINE LCD_DREG PORTA ' Set LCD Data port
DEFINE LCD_DBIT 0 ' Set starting Data bit (0 or 4) if 4-bit bus
DEFINE LCD_RSREG PORTB ' Set LCD Register Select port
DEFINE LCD_RSBIT 4 ' Set LCD Register Select bit
DEFINE LCD_EREG PORTB ' Set LCD Enable port
DEFINE LCD_EBIT 3 ' Set LCD Enable bit
DEFINE LCD_BITS 4 ' Set LCD bus size (4 or 8 bits)
DEFINE LCD_LINES 2 ' Set number of lines on LCD
' DEFINE LCD_LINES 4 ' Set number of lines on LCD
DEFINE LCD_COMMANDUS 2000 ' Set command delay time in us
DEFINE LCD_DATAUS 50 ' Set data delay time in us

CMCON = 7 ' <font color=red>disable analog comparators</font color>RA0-RA3 are digital I/O
TRISA = 0 ' PORT A is output
TRISB = 0 ' PORT B is output
<font color = red> Pause 1000</font color>

RPT:
LCDOUT $FE,1 ' Clear LCD
LCDOUT $FE, $0C 'Cursor off
LCDOUT $FE, $0F ' Blinking cursor on
PAUSE 500 ' Wait 0.5 second for LCD to startup

' For 16x2 LCD
LCDOUT $FE,2, "Hello." ' Display 1st Line
LCDOUT $FE,$C0, "World." ' Display 2nd Line
' For 20x4 LCD
' LCDOUT $FE,2, "Hello." ' Display 1st Line
' LCDOUT $FE,$C0, "World." ' Display 2nd Line
' LCDOUT $FE,$94, "Line 3" ' Display 3rd Line
' LCDOUT $FE,$D4, "Line 4" ' Display 4th Line

PAUSE 10000 ' Wait 10 second

GOTO RPT ' Repeat

END ' End of program

After I posted, I just added following statements to my code. Still no help.

define osc 4 ' Internal OSC 4 MHZ<font color=red> add intrc</font color>
define loader_used 1 ' <font color=red> makes bootloader work</font color>?
@ Device pic16F627A, BOD_ON, LVP_OFF, PWRT_ON, WDT_ON, PROTECT_OFF,<font color=red> INTRC_OSC_NOCLKOUT </font color>

Hello John Paul,
I made some minor tweaks in red above, also be advised RA4 is an open drain output..edit: Oh I see the resistor in your comments, so you got that covered.
JS

[JohnPaul]

Ski,
I am still using the same chip PIC16F627A.
I failed the LED test. I hook up an LED to the Ground then in series to 330 ohm Resistor and a cable at the end. I tap the cable to +5V and tested the LED polarity. Then I tap each of the pin. I tried one LED then also tried all of the output pins. Program below.
How could I have damaged my chip? It is new. How could I be certain my chip is damaged before I toss it to the trash can?

LED6 VAR PORTB.0 ' Pin LED Test
TRISB = 0 ' PORT B is output
RPT:
PAUSE 2000 ' WAIT 1 SECOND
LED6 = 1 ' Turn Pin LED ON

PAUSE 2000 ' WAIT 1 SECOND
LED6 = 0 ' Turn Pin LED OFF

GOTO RPT ' Repeat

END ' End of program

Also tried them all and none of the LED turned on.

LED1 VAR PORTA.2 ' Pin LED Test
LED2 VAR PORTA.3 ' Pin LED Test
LED3 VAR PORTA.4 ' Pin LED Test
LED4 VAR PORTA.5 ' Pin LED Test
LED6 VAR PORTB.0 ' Pin LED Test
LED7 VAR PORTB.1 ' Pin LED Test
LED8 VAR PORTB.2 ' Pin LED Test
LED9 VAR PORTB.3 ' Pin LED Test
LED10 VAR PORTB.4 ' Pin LED Test
LED11 VAR PORTB.5 ' Pin LED Test
LED12 VAR PORTB.6 ' Pin LED Test
LED13 VAR PORTB.7 ' Pin LED Test
LED15 VAR PORTA.6 ' Pin LED Test
LED16 VAR PORTA.7 ' Pin LED Test
LED17 VAR PORTA.0 ' Pin LED Test
LED18 VAR PORTA.1 ' Pin LED Test

TRISA = 0 ' PORT A is output
TRISB = 0 ' PORT B is output


RPT:
PAUSE 1000 ' WAIT 1 SECOND
LED1 = 1 ' Turn Pin LED ON
LED2 = 1 ' Turn Pin LED ON
LED3 = 1 ' Turn Pin LED ON
LED4 = 1 ' Turn Pin LED ON
LED6 = 1 ' Turn Pin LED ON
LED7 = 1 ' Turn Pin LED ON
LED8 = 1 ' Turn Pin LED ON
LED9 = 1 ' Turn Pin LED ON
LED10 = 1 ' Turn Pin LED ON
LED11 = 1 ' Turn Pin LED ON
LED13 = 1 ' Turn Pin LED ON
LED15 = 1 ' Turn Pin LED ON
LED16 = 1 ' Turn Pin LED ON
LED17 = 1 ' Turn Pin LED ON
LED18 = 1 ' Turn Pin LED ON
PAUSE 1000 ' WAIT 1 SECOND

LED1 = 0 ' Turn Pin LED OFF
LED2 = 0 ' Turn Pin LED OFF
LED3 = 0 ' Turn Pin LED OFF
LED4 = 0 ' Turn Pin LED OFF
LED6 = 0 ' Turn Pin LED OFF
LED7 = 0 ' Turn Pin LED OFF
LED8 = 0 ' Turn Pin LED OFF
LED9 = 0 ' Turn Pin LED OFF
LED10 = 0 ' Turn Pin LED OFF
LED11 = 0 ' Turn Pin LED OFF
LED13 = 0 ' Turn Pin LED OFF
LED15 = 0 ' Turn Pin LED OFF
LED16 = 0 ' Turn Pin LED OFF
LED17 = 0 ' Turn Pin LED OFF
LED18 = 0 ' Turn Pin LED OFF

GOTO RPT ' Repeat

END ' End of program

[JohnPaul]

JoeS,

Your posts noted and changes made. I am pondering why my chip is not working. If the chip is damaged, won't the programmer verify step resulted in an error? What's next after LED test failed? I have another pci16gf627A chip. I am afraid that I might damage it too.

Regards,
JohnPaul

[JohnPaul]

ski,

I like your 'heartbeat' practice. I would adapt it as my practice too.

Regards,
JohnPaul

[skimask]

ski,

I like your 'heartbeat' practice. I would adapt it as my practice too.

Regards,
JohnPaul

Put a voltmeter on the OSCx pins. You should get around 2.5v with an external oscillator, or if you've got OSC2 setup as an Fosc/4 output.
I wouldn't think you smoked a chip...as has been noted before, PICs are fairly tough chips, not unbreakable, but tough.
And if for some reason, your PIC is running on the 48khz internal clock, your program will run about 83 times slower than it should...in other words it'll take 166 seconds for your LEDs to blink.

[Archangel]

JoeS,

Your posts noted and changes made. I am pondering why my chip is not working. If the chip is damaged, won't the programmer verify step resulted in an error? What's next after LED test failed? I have another pci16gf627A chip. I am afraid that I might damage it too.

Regards,
JohnPaul

Hi JohnPaul,
You would think so wouldn't you, but the short answer is no, I have killed a few PICs and had programs verify fine, I think I killed the output transistors while the core of the pic remained undamaged. You would do well if using an old breadboard to either replace it or use an ohmmeter to verify all connections, I have been led to the land of little hair as a result of these.
JS

[JohnPaul]

Joes & Ski,
Thank you for the help.

JoeS,
Using an Ohmeter, which pins do I tap, what to expect and why? I would also do the Ohmeter test on a new chip alongside with this chip in question.

Regards,
JohnPaul