Using LabVIEW to write to a LCD display using a USB

[Gerardo09]

Smercurio,

Thank you for your help.  Unfortunately, the manufacturer responded to my email and said that while those serial pins are connected to the MCU, they are currently not being used as serial communication.  They have not yet developed the firmware for that purpose.  They are only there in case they want to develop firmware for those modules in the future. I believe my only option is to return them and get a LCD like the Crystalfontz discussed earlier that come with a driver that communicates serially through a virtual comport. 

[jdpowell]

---

Mudda wrote:

Hi james,

I am working with LCD displays from CrystalFontz. it is CFA 632, I just started understanding the communication. if you dont mind can you share your code with me which you developed for 635?

thanks,

Mudda.

---

Hi  Mudda,

I'm right in the middle of trying to rewrite my prototype CFA635 code at the moment.  Me prototype works, but became a nightmare during development and I would be embarrassed to post it. I'll try and post something in a couple of days.  If nothing else, I can give you subvi's that construct the command packet and interpret the response packets.

 -- James 

[Mudda]

Hi James,

I developed a VI which executes most of the commands for CFA 632 using serial communication. The only command I was having trouble with is "Scroll Off" command. I was successfully able to start the scrolling messages but was not able to stop it. The only I was able to stop the scroll was to send the "Reboot" command.

FYI, the way I was starting the scrolling message was to send the actual test first and then send the command for "scroll on" and after that you send the "enable scrolling".

I am attaching my VI with this thread. If you have any questions let me know. And by the way if you find how to stop the scrolling messages please let me know. I appreciate it.

regards,

Mudda.

[drjdpowell]

Hi Mudda,  Your CFA632 uses a very different (and simpler) communication protocall than the CFA635.  I had misread what you were using as the CFA633, which is similar to my CFA635's.  I don't think my code will help you. 

-- James

[BarryGRAEllc]

Anyone have any more info on communicating to the CrystalFontz 635 LCD display? I have used their 634 successfully.

I have been looking at their 635_WinTest_1.0.exe while I try to replicate the commands using Visa but there seems to be missing information (or I am just not getting it). In their Wintest app they have a packet viewer but it already formats the data so I can not see the raw format that I need to send. I remember on the 634 that "\" were required.

http://www.crystalfontz.com/product/CFA635-TMF-KU1.html has the PDF that on p19 says:

All packets have the following structure:
<type><data_length><data><CRC>
type is one byte, and identifies the type and function of the packet:
TTcc cccc
|||| ||||--Command, response, error or report code 0-63
||---------Type:
             00 = normal command from host to CFA-635
             01 = normal response from CFA-635 to host
             10 = normal report from CFA-635 to host (not in
                  direct response to a command from the host)
             11 = error response from CFA-635 to host (a packet
                  with valid structure but illegal content
                  was received by the CFA-635)

data_length specifies the number of bytes that will follow in the data field. The valid range of data_length is 0 to
22.
data is the payload of the packet. Each type of packet will have a specified data_length and format for data as
well as algorithms for decoding data detailed below.
CRC is a standard 16-bit CRC of all the bytes in the packet except the CRC itself. The CRC is sent LSB first. At the
port, the CRC immediately follows the last used element of data []. See APPENDIX C: CALCULATING THE
CRC(Pg.50) for details.
he following C definition may be useful for understanding the packet structure.
typedef struct
  {
  unsigned char
    command;
  unsigned char
    data_length;
  unsigned char
    data[MAX_DATA_LENGTH];
  unsigned short
    CRC;
  }COMMAND_PACKET;

p23 

0 (0x00): Ping Command
The CFA-635 will return the Ping Command to the host.
type = 0x00 = 010
valid data_length is 0 to 16
data[0-(data_length-1)] can be filled with any arbitrary data
The return packet is identical to the packet sent, except the type will be 0x40 (normal response, Ping Command):
type = 0x40 | 0x00 = 0x40 = 6410
data_length = (identical to received packet)
data[0-(data_length-1)] = (identical to received packet)

Can anyone describe the format to send (1) command that I can start with and build up from there? ie: using LV Visa to a Comm Port.

It would be much appreciated.

[bryan2389]

I am having a similar issue. I am using the EA-DOGM128W-6 (http://www.mouser.com/ProductDetail/ELECTRONIC-ASSEMBLY/EA-DOGM128E-6/?qs=sGAEpiMZZMt82OzCyDsLFKO8Kn... via a USB drive. Has anyone worked with this type of screen or know how to help get this incorporated into the LabVIEW vi or if there is a VI that can help read/display to the screen.

The screen accepts bitmaps and through saved files on the computer, it is able to display them, however, getting them displayed on the screen through LabVIEW, is posing a problem.

Thanks!

[Kristoff2]

bryan2389,

The link you provided returns a 'no results' page on mouser.  

How do you interface with the screen?  Are you able to communicate with it via other software?  If so what software / language?

Please provide as much information as possible.

Regards,

Sam K

Applications Engineer

National Instruments

www.ni.com/support

[bryan2389]

We got that all figured out. Thanks though!