LCD 20*4, C2004A, on i2C. E, E1, E2 signals and PCF8574 prob

gpat · Joined: 18 Apr 2006 Posts: 24

Dear all
I just bought the LCD:
http://www.ebay.com/itm/180939111604?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

which has the LCD C2004A +PCF8574

with
PIN ASSIGNMENT / PIN SYMBOL FUNCTION
1 Vss Power Supply (0V)
2 Vdd Power Supply (+5V)
3 Vo Contrast Adjust
4 RS Data/Instruction Register Select
5 R/W Read/Write
6 E Enable Signal
7~14 DBO~DB7 Data bus Line
15 A Power Supply for LED BL (+)
16 K Power Supply for LED BL (-)

I disconnected the PCF 8574 from the LCD board and works fine with 4pin mode.
I cant operate it with the I2C and PCF8574.

As I can see in the lcd_i2c.lib we need pins E1 and E2 (?) as seen in the
AN #118 - I2C LCD and Keboard library example ( http://www.mcselec.com/index.php?option=com_content&task=view&id=82&Itemid=57)
since
P6 of PCF8574 is connected to LCD-E2
P7 of PCF8574 is connected to LCD-E1

But the LCD has only one Enable signal.
What is your suggestion? concerning the E,E1,E2 signals

PS: Don't buy this LCD, since the pinout is different than the normally used pinout of PCF8574+LCD in Bascom, which I had to change also, but I dont know what to connect to E....
(BASCOM-AVR version : 2.0.7.3 , Latest : 2.0.7.6 )

kimmi · Joined: 24 Feb 2006 Posts: 1922 Location: Denmark

Hi,
Check pins on I2c board to lcd it may NOT be same setup as used in Lcd_i2c

as I see 8574 pins to lcd is NOT same layout pin by pin !!

8574 pin 12 is data7 (pin 14 lcd)
8574 pin 11 is data6 (pin 13 lcd)
ect
see i2c to lcd interface.pdf in AN #118 for pins
LCD- E1 (or E on 1 and 2 line LCD) use P7 for 2 line

gpat · Joined: 18 Apr 2006 Posts: 24

Paulvk · Joined: 28 Jul 2006 Posts: 1257 Location: SYDNEY

Hello gpat

"Can we brake a *.bas file to several and combine them together in the main program?"

Yes bascom has a project mode where you can put all your sub's ect into seperate files then with an $include it brings them in have a look at my ENC28J60 webserver project in the blog section its over 10000 lines long.

Regards Paul

kimmi · Joined: 24 Feb 2006 Posts: 1922 Location: Denmark

gpat · Joined: 18 Apr 2006 Posts: 24

Thank you all.
I will check them out the next days
George

vvogeley · Joined: 20 Feb 2008 Posts: 8

Hi gpat,

here is a link to a german Bascom forum
http://www.mcselec.com/index2.php?option=com_forum&Itemid=59&page=viewtopic&t=10904&highlight=i2c+lcd

with this lib (Lcd_i2c_v2.lib) you can define every PCF8574 pin .
look here:

vvogeley · Joined: 20 Feb 2008 Posts: 8

Sorry, now the correct link

http://bascomforum.de/

best regards
Volker

aphawk · Joined: 23 Jan 2010 Posts: 175 Location: Brazil

I see in the German Bascom Forum that someone make modifications in the lcd_i2c_v2.lib, creating the lcd_i2c_v3.lib, that can control the backlite if I use only 4 bits mode and R/W tied to ground. This is very interesting !

But I can't understand German, and using only the Google Translate is very difficult to get the code and the new library.

Maybe someone that is fluent in both German and English can post here this new library, with the example code ?

Thanks !

Paulo

Mrshilov · Joined: 24 Jan 2009 Posts: 314 Location: Russia

Library, example code and Proteus design in archive. But it don't work.
I tried first version from AN#118, second from Ludwig and this with 16x2, 40x2, 20x4 LCD. In Proteus and hardware, but nothing. Init display, cursor is shown, text not shown.
I don't know what's wrong...

MWS · Joined: 22 Aug 2009 Posts: 2335

Mrshilov · Joined: 24 Jan 2009 Posts: 314 Location: Russia

I check this in non-arduino LCDs and non-Arduino PCF8574 plate. Maybe Proteus model of PCF8574 is not fully correct, but in hardware don't work too. Chipsets of LCDs is unknown (compound drop), but while connected wia 4- or 8-bit directly to controller they works fine like HD44780 & KS0066 compatible.

MWS · Joined: 22 Aug 2009 Posts: 2335

Mrshilov · Joined: 24 Jan 2009 Posts: 314 Location: Russia

External pullup, of course, connected.
I use hardware I2C-pins because I try hardware and software I2C. In both cases PCF8574 works, display is inits and cursor is shown.
I try without I2C delay and with it from 1 to 30.
Note! Without string "Display On" cursor is not shown. In all examples I don't see this string.
Mr. MWS! Code is very simple and Proteus design is in archive. Please, make it work. It will be more informative for me.

MWS · Joined: 22 Aug 2009 Posts: 2335

Neither I do have nor use Proteus.
Don't see your code in front of me now, so I'm not sure, if you already use Init LCD, in case not, try to issue some Wait an then InitLCD, maybe the hardware needs more time to get ready.
Did you double-check the actual clock frequency of the ATM32 against the code? In case this is wrong, timing for the display is not correct. Why it would work then without expander, would be the next question then.
Basically I see nothing wrong in the lcd_i2c.lib, others have used it successfully.
About the v3-lib I can't and won't tell anything.