LCD display using DAQ USB6008

[KayK]

thank Dennis and Morgol so much for helping me...
but i stil dun reali understand how to program a LCD...as im really weak as i know i am...haiz
i follow the steps on the datasheet to initialize the LCD and try to clear the display of LCD but cant make it...
the LCD stays like what it is when i connected the power supply.....i dun understand why...
if this continue to happen then i cant even try to display any number on the LCD...
i check all the digital I/O pins on the USB6008 and they are functioning properly...
can u teach me how to program this LCD? im oso not very familiar in using the DAQmx....all i try to use before is just using the DAQ Assistant...
thats why i dun really understand how the VI u send me functions...i try to connect the VI to the LCD through the DAQ...but the display doesn't even change a bit....
can u please help me...please please...im reali having a big headache now,nobody can help me...
please....i reali appreciate your help...
thank you so much...

[KayK]

anyone..please...
i need help in programming a 16x2 character LCD display using LabVIEW and USB6008...
please please help.... 

[Dennis_Knutson]

Post the code you've written and provide details on how you have wired the 6008. The code I gave you does not do any of the initialization. It was only an example on how to write characters.

[RnDMonkey]

First off, do a quick sanity check by making sure that the contrast setting is right. I had my contrast so out of whack initially that you couldn't see it working at all.

In the mean time, I will work on adding some notes to my code, because I realize that I didn't really annotate anything.

[KayK]

hmm...i have included the VI i try to use to test the LCD here...
i just use 3 control buttons to control the high/low of the RS,R/W and Enable pins...connect to DAQ Assistant using line output...
while for the DB0 - DB7 data bits, i uses an array and connected it to DAQ Assistant using port0 as output, and port0 have 0-7 pins...
and so i follow the steps taught in the datasheet and send the data manually...this is what im doing....
i guess maybe its wrong as the LCD have no response at all....so hope u guys can help me out....

[RnDMonkey]

When you first power up the LCD it will show all squares. Do you at least see that?

[Dennis_Knutson]

Major problems. For both DAQ Assistants, you have defined the same pins (port0). Whenever one DAQ Assistant runs, it will overide whatever settings you have for the other DAQ Assistant. You also have no idea which DAQ Assistant will run first. At the very least, you should define the individual pins for each DAQ Assistant. Assign the data pins and the control pins. You then need to do some basic dataflow. Wire an error out to an error in to control execution order.

You really need to spend some time going through the tutorials available at Getting Started with DAQmx and taking some of the LabVIEW Tutorials.

[KayK]

yup..i manage to see all squares after powering up the LCD...and thats the last things i can see...
after i test,the display is stil the same....please help help...
oh thanks Dennis...i have go through also the Getting Started with DAQmx...but just not reali understand as my skills are weak yet...
by the way, hope u can stil help me with my LCD displays...
thank you very much...

[RnDMonkey]

Dennis,

I'm not seeing any problems with those DAQ assistants. I see the top one as using port0/line0:7, and the bottom one as using port1/line0:2, which would be fine. And as far as data flow, if Kay hits the "run continuously" button, data flow is irrelevant since the display will only update when Kay changes the E line from high to low, and the DB7-DB0, RS, and R/W bits will be set from previous iterations.

Kay,

Make sure you are performing all the initialization steps, such as the example in the datasheet for initializing by instruction.

Also, make sure your contrast is appropriate. When you turn it on, adjust it so the squares are half-way between all-dark and all-gone, just to be sure.

I've annotated my code to kind of explain how it works, so let me know if that helps.

[Dennis_Knutson]

Oops, you are correct. I went back and looked at the pin assignments again and did not see anything wrong. It would still help to know the physical wiring that was done.

I never use the run continuous and never use the DAQ Assistant for that matter. I'm not convinced that by using either, the tasks are not getting started and cleared each time the code is run.