Newhaven 4x40 LCD, issues!

[mackrackit]

Not sure where you saw Darrel connecting RW to the PIC, in fact he says not to in this post.
http://www.picbasic.co.uk/forum/show...=2388#post2388

The R/W pin is exactly what it says Read/Write, with 0 being Write.

Do you have the contrast pin connected to a pot as recommended? That is the most common problem. That should be pin #3 on the display. Not sure why the data sheet does not so it. Got to have contrast control.

[Christopher4187]

Sorry, it wasn't Darrell. It was NavMicroSystems in this picture. Anyhow, I literally get nothing. I can't even see the screen flicker. I've verified it has 4.8V at the power input and I've tried using a pot to adjust the contrast. I've only used serial LCD's from SEETRON in the past so this is new to me. Is there a basic way to test the screen? Like applying power to the LCD and +5 to another pin will display something?

[mackrackit]

I do not know of a test.
Post your code and connections/schematic.
Maybe we will be able to see the problem.

[Christopher4187]

Here is what I have:

DEFINE OSC 20
@ __CONFIG _CONFIG1L, _PLLDIV_5_1L & _CPUDIV_OSC1_PLL2_1L & _USBDIV_2_1L
@ __CONFIG _CONFIG1H, _FOSC_HSPLL_HS_1H & _FCMEN_OFF_1H & _IESO_OFF_1H
@ __CONFIG _CONFIG2L, _PWRT_OFF_2L & _BOR_OFF_2L & _BORV_3_2L & _VREGEN_ON_2L
@ __CONFIG _CONFIG2H, _WDT_OFF_2H & _WDTPS_32768_2H 
@ __CONFIG _CONFIG3H, _CCP2MX_ON_3H & _PBADEN_OFF_3H & _LPT1OSC_OFF_3H & _MCLRE_ON_3H
@ __CONFIG _CONFIG4L, _STVREN_ON_4L & _LVP_OFF_4L & _ICPRT_ON_4L & _XINST_OFF_4L


loopcount var word
;----[ Change these to match your LCD ]--------------------------------------- 
LCD_DB4    VAR PORTE.1 
LCD_DB5    VAR PORTA.3 
LCD_DB6    VAR PORTA.4 
LCD_DB7    VAR PORTE.2
LCD_RS     VAR PORTD.3 
LCD_E      VAR PORTA.5 
LCD_Lines  CON 2 ' # of Lines on LCD, 1 or 2 (Note: use 2 for 4 lines) 
LCD_DATAUS CON 50 ' Data delay time in us 
LCD_COMMANDUS CON 2000 ' Command delay time in us 
INCLUDE "LCD_AnyPin.pbp" ; *** Include MUST be AFTER LCD Pin assignments ****
; 
;----[ Your Main program starts here ]---------------------------------------- 
'LoopCount VAR WORD PAUSE 500 : LCDOUT $FE,1 : PAUSE 250 ; Initialize LCD (You may not need this, ; but some displays are picky) 
;
Main: LCDOUT $FE,1 ; clear screen 
LCDOUT $FE,$87,"Hello,",$FE,$C8,"From DT!" 
;
FOR LoopCount = 0 TO 65535 
    LCDOUT $FE,$80, IDEC LoopCount 
    LCDOUT $FE,$C0, IHEX4 LoopCount 
NEXT LoopCount 
GOTO Main

Pin connections are as follows:


1 VSS
2 VDD
3 10K POT
4 PORTD.3
5 VSS
6 PORTA.5
7 N/C
8 N/C
9 N/C
10 N/C
11 PORTE.1
12 PORTA.3
13 PORTA.4
14 PORTE.2
15 N/C
16 N/C

[mackrackit]

Did you turn the ADC off someplace ?

[Christopher4187]

That's the entire code. I rechecked everything and everything looks okay. I bought two LCD's so when I get home I'll try the other one. I don't know what else I can check. I have an old Mikroelectronica board that has pins for parallel LCD's so maybe I'll use that with the standard code (all pins on the same port) to see if it's my hardware or software that's causing the issue.

[Darrel Taylor]

With those configs ... the PIC is running at 48mhz, not 20.
So change the DEFINE OSC 20 to DEFINE OSC 48.

And like Dave mentioned ... add ADCON1 = $0F before the LCD pins/include.

[MOUNTAIN747]

Christopher, I had all my wiring correct and the code looked good but I still had no display. The problem was Vo. The contrast was a critical adjustment. Once I found the sweet spot, just above 0 VDC, all was well.

I've attatched a txt file with the code to test the LCD using E1 & E2, no other hardware needed. R/W can be tied to GND or to an output. Make the necessary VAR pin assinment changes. This code will write to all four lines without using LCDOUT command.

Wayne

Newhaven_4x40_Test Code (1).txt