Running LCD Display 4 Bit Mode Libraries ? Init ?

autoguider · Joined: 24 Sep 2007 Posts: 82 Location: Aachen

Dear All,
I am asking for your advice to get the LCD Display operating.

The PowertipPC 1602 F Display is not operating on a ATMeaga 168 P in 4 Biut Mode.
I am using the 2.0.7.6 version of the Bascom compiler.

In the program the processor is indicated by following files/ Libraries:

$lib "mcs.lbx"
$regfile = "m168def.dat"

..
later on the LCD display is introduced to the compiler by:

Config Lcd = 16x2
Config LCDBUS = 4
Config Lcdpin = Pin , Db4 = Portd.6 , Db5 = Portd.4 , Db6 = Portd.7 , Db7 = Portb.0 , E = Portd.3 , Rs = Portd.2

The unused data pins of the display are connected to ground. R/W is set to write.

Do I need a different library ?
Is the declaration o.k. ?
Is some special init procedure requires or is this done within the declaration ?

This is the first time that I control the display in 4 bit mode.
Perhaps I cannot see the forest because of the trees.

Please be so kind to give me some advice

best regards
Christian

(BASCOM-AVR version : 2.0.7.6 , Latest : 2.0.7.6 )

i.dobson · Posted: Thu Oct 31, 2013 6:11 am Post subject:

Hi,

I usually use something like this :-

Config Lcdpin = Pin , Db4 = Portc.5 , Db5 = Portc.4 , Db6 = Portc.3 , Db7 = Portc.2 , E = Portc.6 , Rs = Portc.7
Config Lcd = 20x4
initlcd

note I don't use the Config LCDBUS = 4 command. and I just leave the unused Pins Floating (not connected).

Are you sure that you have the LCD control voltage Setup correctly/try adjusting the LCD Display voltage Abit.

Regards
Ian Dobson

albertsm · Joined: 09 Apr 2004 Posts: 6198 Location: Holland

you have connected WR to ground?
always check all pins to see if they function with a simple test code:

config portb.0=output

do
toggle portB.0 'toggle pin and measure with DVM to see if the pin toggles
waitms 1000
loop

checking contrast is a good idea too.

autoguider · Joined: 24 Sep 2007 Posts: 82 Location: Aachen

Dear Ian, Dear Albert.
many thanks for your advice.
I will do some testing now.

While reading your advice a further question arises:
Do I habe to config e.g. PORTB.0 = Output before I do the config Lcdpin =Pin ,...., DB7 = PORTB.0 ?

Pin5 ( R/W) of the display is connected to ground. This means that only write access to the display is possible.

I also checked on the contrast voltage. It is low enough.
There are dark rectangles at the location of the letters in one line of the 2 line display only.

I you have some further ideas please let me know.

Now I will do some testing.

best regards

Christian

albertsm · Joined: 09 Apr 2004 Posts: 6198 Location: Holland

the config lcdpin will set the data direction of the pin.
Just test these pins : Db4 = Portd.6 , Db5 = Portd.4 , Db6 = Portd.7 , Db7 = Portb.0 , E = Portd.3 , Rs = Portd.2
Maybe they are wired different. or some other hardware is connected to them as well?
And make sure you indeed connect to DB4-DB7 of the LCD.
If you see black blocks the contrast is ok.

petros047 · Joined: 14 Mar 2012 Posts: 84

I use this lib and always work but you have to connect the w/r pin to mc in order to work.
this lib read the w/r pin as flag to calculate the necessary delay who lcd need for various commands.

$lib "lcd4busy_anypin.lbx"
'lcd config
Config Lcdpin = Pin , Db4 = Portc.2 , Db5 = Portc.1 , Db6 = Portc.0 , Db7 = Portd.7 , E = Portc.3 , Rs = Portc.5 , Wr = Portc.4
Config Lcd = 16 * 2
Initlcd
Display On
Cursor Off

autoguider · Joined: 24 Sep 2007 Posts: 82 Location: Aachen

Dear All,
many thanks for your advice.

In the meantime I got the LCD working in 4 bit mode.
I found some behaviour of the display which is strange to me.

If there is a wait command after data is written to the LCD using the lcd command then the display does not show any data until it comes to the next access to the display.
The display is not darkened it just shows nothing.

When putting a wait command after e.g. locate then the display remains as it should.

So it means that there must not be a wait command after a lcd command.

Is this normal ?

best regards

Christian

For clarification here is the code:
Config Lcd = 16*2

Config Lcdpin = Pin , Db4 = Portd.6 , Db5 = Portd.4 , Db6 = Portd.7 , Db7 = Portb.0 , E = Portd.3 , Rs = Portd.2
initlcd

Dim i as integer
dim Line_1 as string*16
dim Line_2 as string*16
dim dummystring as string*3
i=0
line_1 = "thisisline#"
cls
lcd line_1
line_2 ="QWERTzYXASDY"
wait 1
lowerline
lcd line_2

waitms 1000
Cursor Off Noblink

' Now there is the endless counting loop

loops:
dummystring =str(i)
dummystring = " " + dummystring

locate 1, 12 'position to line 1 Pos 12
waitms 50 'give time for executing command
lcd dummystring 'write short string to line 1

waitms 1000 '<-- no information visible on LCD display but data is still in the memory

locate 2,12 'position to line 2 Pos 12 Information is displayed
waitms 50 'give time for executing command
lcd dummystring ' write short string to defined position

locate 1, 12 '<---- if removed then no information visible on LCD
waitms 1000 '<------ this works if locate command is prior

i=i+1
'wait 1
if i=100 then i=0

goto loops

albertsm · Joined: 09 Apr 2004 Posts: 6198 Location: Holland

your code does not show if you use the default lib or some other lib?
and do you have WR connected to ground or a pin ?
what i do miss : $crystal = somevalue

that is important for timing.

autoguider · Joined: 24 Sep 2007 Posts: 82 Location: Aachen

Dear Albert,

sorry about the lack of information.
Here it comes:
It is the default lib
wr is connected to ground
There is a 6 MHz crystal in operation. No division of the external clock.

best regards
Christian

albertsm · Joined: 09 Apr 2004 Posts: 6198 Location: Holland

please post the complete code that contains $regfile , $crystal, $hwstack and $swstack. Otherwise i need to guess it.

you wrote earlier that you got the lcd working after initial problems. what was the source of the problem? what would it not work in the first place?

instead of ;

loops:
.. code here
goto loops

you can better write :

do
..code here
loop

right after the LCD command the lcd should display the information. a locate only positions the cursor.
is no other hardware connected to the pins? especial the pins connected to the E-line and RS-line?

autoguider · Joined: 24 Sep 2007 Posts: 82 Location: Aachen

Dear Alberet,
here is the source text:

'$PROG &HFF,&HF7,&HDF,&HFF' generated. Take care that the chip supports all fuse bytes.

$lib "mcs.lbx"
$regfile = "m168def.dat" ' specify the used micro
$crystal = 6000000 ' used crystal frequency
$baud = 19200 ' use baud rate
$hwstack = 90 ' default use 32 for the hardware stack
$swstack = 60 ' default use 10 for the SW stack
$framesize = 40

Config Lcd = 16*2
Config LCDBUS = 4
Config Lcdpin = Pin , Db4 = Portd.6 , Db5 = Portd.4 , Db6 = Portd.7 , Db7 = Portb.0 , E = Portd.3 , Rs = Portd.2
initlcd

Dim i as integer
dim Line_1 as string*16
dim Line_2 as string*16
dim dummystring as string*3

i=0
line_1 = "thisisline#"
cls
lcd line_1

line_2 ="QWERTZYXASDY"

wait 1
lowerline
lcd line_2

waitms 1000
Cursor Off Noblink

do

dummystring =str(i)
dummystring = " " + dummystring

locate 1, 12 'position to line 1 Pos 12
waitms 50 'give time for executing command
lcd dummystring 'write short string to line 1

'waitms 1000 '<-- no information visible

locate 2,12 'position to line 2 Pos 12
waitms 50 'give time for executing command
lcd dummystring ' write short string to defined position

locate 1, 12 '<---- if removed then no information visible on LCD
waitms 1000 '<------ this works if locate command is prior

i=i+1
'wait 1
if i=100 then i=0

loop

The wait commands following the lcd commands ( e.g. lines 30. 35, 51) cause the display to show nothing.
If e.g. the command locate occurs after a lcd command but before a wait command ( see lines 49 .. 53) everything runs well.

best regards

Christian

albertsm · Joined: 09 Apr 2004 Posts: 6198 Location: Holland

i changed your code a bit. first of all, the delays are not necessary.
only 1 delay should be placed so the lcd has time to show the info. (at the end of the loop). Otherwise the result would be erased by the next value.

here is your code:

autoguider · Joined: 24 Sep 2007 Posts: 82 Location: Aachen

Dear Albert,
many thaks for your efforts and recommendations.
Here is a link to the datasheet of the display: http://www.datasheetarchive.com/PC1602-F-datasheet.html

So far I have not tried an other display but I will do.

The installation is on a soldered board. like this one http://www.reichelt.de/directlink/Lochrasterplatine/index.html?&ACTION=2&GROUPID=3372&&SHOW=1&SID=10TivsyX8AAAIAABt1Y1g2f6efa2336525b970a9f72f7e2a56484&SEARCH=LOCHRASTERPLATINE

The internal connections are done with enameled copper wire.
Before I do a printed circuit board I want to do the test with this prototype.
Enameled copper wire is similar to a multi Layer PCB Wink

thanks again
Christian

albertsm · Joined: 09 Apr 2004 Posts: 6198 Location: Holland

it seems like a standard display.
it is very wise to test before you make a pcb.
best to keep the wires short as possible.
and make sure you have a good stable power and decoupling caps at vcc.
very important is that the $crystal=6000000 matches the actual oscillator speed.
that is simple to test :

config portb.1 =output 'use a free pin
do
toggle portb.1 'on and off must be ca. 1 sec.
waitms 1000
loop