LCDOUT custom commands - how to?

**mister_e** · - 24th November 2006, 00:34

Nope, the first LCDOUT should take care of the initialisation. For safety sake use a 500mSec-1Sec at the top of your code before the first LCDOUT.

LCDOUT $FE,1 just clear the display.

Be sure you don't use your LCD on analog i/o AND/OR open drain type without using the right method (pull-up, set all I/Os to digital)

As usual, your WHOLE code and PIC# will help.

**flotulopex** · - 24th November 2006, 14:17

I'm still not sure how to connect the datalines from the display to the PIC (is it DB0 = D7 and so on or is it DB0 = D4 and so on).

Here is my code:

Code:

'PIC 16F88

' LCD circuitery
'23,24,25,26,32,33,34,35,40 - Vdd (+5V)
'27,38  - Vss (GND)
'28 DB0 - PORTA.0
'29 DB1 - PORTA.1
'30 DB2 - PORTA.2
'31 DB3 - PORTA.3
'39 RS  - PORTA.4
'36 E   - PORTA.6
'37 R/W - PORTA.7


DEFINE LCD_DREG PORTA       'LCD data port 
DEFINE LCD_DBIT 4           'LCD data starting bit 0 or 4 
DEFINE LCD_RSREG PORTA      'LCD register select port 
DEFINE LCD_RSBIT 4          'LCD register select bit 
DEFINE LCD_EREG PORTA       'LCD enable port 
DEFINE LCD_EBIT 6           'LCD enable bit 
DEFINE LCD_RWREG PORTA      'LCD read/write port
DEFINE LCD_RWBIT 7          'LCD read/write bit
DEFINE LCD_BITS 4           'LCD bus size 4 or 8 
DEFINE LCD_LINES 2          'Number lines on LCD 
DEFINE LCD_COMMANDUS 2000   'Command delay time in us 
DEFINE LCD_DATAUS 50        'Data delay time in us


' Register settings
OSCCON     = %01100000      'Internal RC set to 4MHZ
ANSEL      = %00000000      'Disable Analogue Inputs
OPTION_REG = %01000000      'Enable PORTB pullups


START:
    Lcdout $FE, 1           'Clear screen


MAIN:
    pause 1000
    lcdout $FE, 2,   "This is line one"
    lcdout $FE, $C0, "This is line two"
    goto MAIN

end

**Melanie** · - 24th November 2006, 14:34

This...

'28 DB0 - PORTA.0
'29 DB1 - PORTA.1
'30 DB2 - PORTA.2
'31 DB3 - PORTA.3

is not compatible with this...

DEFINE LCD_DREG PORTA 'LCD data port
DEFINE LCD_DBIT 4 'LCD data starting bit 0 or 4

...and double-check with the Datasheet that you've disabled all Analogue Functions on PortA.

**flotulopex** · - 24th November 2006, 15:34

The display's datasheet makes me connect the lines D4 to DB3, D5 to DB2, D6 to DB1 and D7 to DB0 (see attachment "DB-Lines_connections.jpg"). This is why I thought the starting bit would be the fourth.

I changed:

Code:

DEFINE LCD_DREG PORTA       'LCD data port 
DEFINE LCD_DBIT 0           'LCD data starting bit 0 or 4

and added:

Code:

ADCON0.0   = 0              'Disable Converter Module

I went through the PIC's datasheet and couldn't find other settings that could affect the A ports. Still, the display looks just dead.

I have two of them and react the same. I changed for my second 16F88 and the result is same too.

**keithdoxey** · - 24th November 2006, 15:53

Normally for a 4 bit bus

DB0-DB3 = D4-D7

Also if you are using a 16F88 check the ANSEL register

**flotulopex** · - 24th November 2006, 16:23

ANSEL is set to have all analog ports disabled.

As you suggested, I connected DB0 to D4 and so on...

Still nothing happens.

I'm just suprised that the display don't even flickers a little. It looks just like dead. Two displays doing the same makes me think I'm doing something wrong.

Is is right to say that to make it work the Enable bit must be high? If yes, I could at least mesure it with my logic probe or oscillo....

What can I "electrically" check else to minimise the cabling error risk?

**keithdoxey** · - 24th November 2006, 17:15

Is there (or should there be) a contrast control that needs adjusting ?

**flotulopex** · - 28th November 2006, 14:37

I'm reading the ST7036 driver's data sheet and I can't find where the operation voltage should be set.

The difference I see between the 3.3V and 5V configuration are the "Voltage Booster" and "Voltage Follower". Okay, but what would be the settings?

What is the "Bias" setting for?

**keithdoxey** · - 28th November 2006, 16:49

Originally Posted by flotulopex

I'm reading the ST7036 driver's data sheet and I can't find where the operation voltage should be set.

The difference I see between the 3.3V and 5V configuration are the "Voltage Booster" and "Voltage Follower". Okay, but what would be the settings?

What is the "Bias" setting for?

The registers where you can see the differences are where the values are set. The values you need are shown in Binary. just convert that to HEX and you have your commands eg Power command register for 5v working is shown as 0101 0010 which is $52 so

LCDout $FE, $52 should do the trick.

You mey not even need to convert it.... you may be able to send

LCDout $FE, %01010010.

I dont know the exact purpose of the Bias setting but as they give you the required values that is what you should use.

**flotulopex** · - 28th November 2006, 21:07

Well,

I got an answer from EA. They say they don't have any negative feedback about their displays. I shall send them my program and a picture (already done).

I fully checked my PIC with LEDs and it's okay whithout any doubt.

I have recabled the circuit with coloured wires to make it easy to see if I miss something obvious to you (see attachments).

The code I will send to AE is this:

Code:

include "16F88-FUSES.BAS"

'PIC 16F88 - 4MHz

' LCD circuitery
'23,24,25,26,32,33,34,35,40 - Vdd (+5V)
'27,38  - Vss (GND)
'31 DB0 - PORTB.0
'30 DB1 - PORTB.1
'29 DB2 - PORTB.2
'28 DB3 - PORTB.3
'39 RS  - PORTB.4
'36 E   - PORTB.5
'37 R/W - Vss (GND)


' Wires from programmer (AN589)
'Black = GND (Vss)
'Red = +5V (Vdd)
'Yellow = MCLR
'Orange = Clock
'Brown = Data


DEFINE LCD_DREG PORTB       'LCD data port 
DEFINE LCD_DBIT 0           'LCD data starting bit 0 or 4 
DEFINE LCD_RSREG PORTB      'LCD register select port 
DEFINE LCD_RSBIT 4          'LCD register select bit 
DEFINE LCD_EREG PORTB       'LCD enable port 
DEFINE LCD_EBIT 5           'LCD enable bit 
DEFINE LCD_BITS 4           'LCD bus size 4 or 8 
DEFINE LCD_LINES 2          'Number lines on LCD 
DEFINE LCD_COMMANDUS 2000   'Command delay time in us 
DEFINE LCD_DATAUS 50        'Data delay time in us


OSCCON     = %01100000      'Internal RC set to 4MHZ
ANSEL      = %00000000      'Disable Analogue Inputs
OPTION_REG = %01000000      'Enable PORTB pullups
CMCON      = %00000111      'Disable Comparators


ManualLCDInit:
    FLAGS=2  ' Void PBP lcd initialisation... it's a nice feature !!!
    PAUSE 500
    Lcdout $FE, $33
    Lcdout $FE, $33
    Lcdout $FE, $20 ' official 4 bit mode
    @  bsf LCD_EREG, LCD_EBIT
    PAUSEUS 20
    @  bcf LCD_EREG, LCD_EBIT
    Lcdout $FE, $28 ' Function Set
    Lcdout $FE, $14 ' Bias
    Lcdout $FE, $78 ' Contrast set
    Lcdout $FE, $5E ' Power/Icon/Contrast
    Lcdout $FE, $6A ' Follower control
    Lcdout $FE, $0C ' Display ON
    Lcdout $FE, $01 ' Clear display
    Lcdout $FE, $06 ' Entry mode Set
   ' --------------------------------- End LCD init!

    LCDOUT $FE,1,"Line1",$FE,$C0,"Line 2"

LOOP: 
    Goto LOOP

end

Keithdoxey, thank you for your help to make me understand how to read the registers values. I'm okay now with this.

Would I really have killed 2 displays???

**keithdoxey** · - 28th November 2006, 21:32

Originally Posted by flotulopex

Well,

I got an answer from EA. They say they don't have any negative feedback about their displays. I shall send them my program and a picture (already done).

I fully checked my PIC with LEDs and it's okay whithout any doubt.

I have recabled the circuit with coloured wires to make it easy to see if I miss something obvious to you (see attachments).

Thats much clearer

Would I really have killed 2 displays???

Hard to say. There is a line in the datasheet that says "Note that the COG technology means that the current capacity of the outputs is limited." It may also mean that COG technology is more susceptable to damage from static electricity.

With a breadboarded circuit there is always a possiblility of accidental shorts and also open circuits. Some devices can be damaged if a voltage is applied to pins when the device itself is unpowered. A loose connection could cause that situation to arise.

I somehow killed some pins on a PIC16F88 but to my knowledge I didnt do anything that was likely to have damaged it. Likewise I have also had solder bridges and other accidental shorts that you would expect to cause damage and things survive.

Its one of the great mysteries !!!!

**keithdoxey** · - 28th November 2006, 22:08

One more thought.

Add a 0.1uF capacitor across PIC 5 and PIC 14

Add a 0.1uF capacitor across LCD 26/27

Wont do any harm and if there is noise present on the supply it could clean it up.

**Archangel** · - 28th November 2006, 23:55

Unless you intend on A/D on:

Code:

DEFINE LCD_DREG PORTB       'LCD data port 
DEFINE LCD_DBIT 0           'LCD data starting bit 0 or 4 
DEFINE LCD_RSREG PORTB      'LCD register select port 
DEFINE LCD_RSBIT 4          'LCD register select bit 
DEFINE LCD_EREG PORTB       'LCD enable port 
DEFINE LCD_EBIT 5           'LCD enable bit 
DEFINE LCD_BITS 4           'LCD bus size 4 or 8 
DEFINE LCD_LINES 2          'Number lines on LCD 
DEFINE LCD_COMMANDUS 2000   'Command delay time in us 
DEFINE LCD_DATAUS 50        'Data delay time in us


OSCCON     = %01100000      'Internal RC set to 4MHZ
ANSEL      = %00000000      'Disable Analogue Inputs
<font color="red">ADCON1 = 7 ' or ADCON1 = %00000111</font> 'Disable A/D converter
OPTION_REG = %01000000      'Enable PORTB pullups
CMCON      = %00000111      'Disable Comparators


ManualLCDInit:
    FLAGS=2  ' Void PBP lcd initialisation... it's a nice feature !!!
    PAUSE 500
    Lcdout $FE, $33
    Lcdout $FE, $33
    Lcdout $FE, $20 ' official 4 bit mode
    @  bsf LCD_EREG, LCD_EBIT
    PAUSEUS 20
    @  bcf LCD_EREG, LCD_EBIT
    Lcdout $FE, $28 ' Function Set
    Lcdout $FE, $14 ' Bias
    Lcdout $FE, $78 ' Contrast set
    Lcdout $FE, $5E ' Power/Icon/Contrast
    Lcdout $FE, $6A ' Follower control
    Lcdout $FE, $0C ' Display ON
    Lcdout $FE, $01 ' Clear display
    Lcdout $FE, $06 ' Entry mode Set
   ' --------------------------------- End LCD init!

    LCDOUT $FE,1,"Line1",$FE,$C0,"Line 2"

LOOP: 
    Goto LOOP

end

**flotulopex** · - 29th November 2006, 16:10

... still nothing on the display.

May I ask what the "FLAGS=2" does?

keithdoxey suggested that the breadboard could be a possible source of problems.

I'll build the circuit up on another breadboard and I will see what happens.

**Darrel Taylor** · - 29th November 2006, 22:56

PBP uses FLAGS.1 (LCDINITFLAG) to remember that it's already initialized the LCD. By setting it to 1, you can make PBP think it's already done, then you can go ahead and do the init manually.

I don't think the Proto-Board itself would cause the display not to work. But I do agree with Keith in that somewhere along the line, something was probably wired wrong, then both displays were tried, and now both displays are most likely dead. It only takes a couple ms of reverse power to fry them.

The reason I say that is because LCD's that haven't been initialized always show black squares on 1 line. From what I understand, you don't even get those.

It may be time to cut your loses, and move on.

Thread: LCDOUT custom commands - how to?

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