Author Topic: NHD-0108BZ-RN-YBW-33W -- NO display!!  (Read 2807 times)

w9001156

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NHD-0108BZ-RN-YBW-33W -- NO display!!
« on: April 29, 2015, 02:14:46 PM »
Hi,

I try to use NHD-0108BZ-RN-YBW-33V for my project.
But I ran into one issue, after initialization, no any display on the LCD,

but I check the interface signal waveform (rs,rw,e,data) with LA. It seems that this module works well.

1) 4-bit Interface setting works.
2) Read "Busy Flag" is OK.
3) When I write data out, I check "Busy Flag" and "Address Count", both values looks normal.

But No any display on the screen?

Would someone give me some suggestion for this issue?

Thanks,
May
« Last Edit: April 29, 2015, 03:47:50 PM by w9001156 »

w9001156

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Re: NHD-0108BZ-RN-YBW-33W -- NO display!!
« Reply #1 on: April 30, 2015, 07:43:23 PM »
Hi,

Can anyone help on this?

1) What voltage should be on V0 PIN?  Is 0.1v enough?
2) I am using HW-verilog on FPGA to implement LCD controller, not by CPU software. So if I want to output Number "1", Should I use asicii code "0x31", is this correct?

I am following the same steps as the following link, but with 4-bit interface.
http://www.newhavendisplay.com/app_notes/8_bit_character_C.txt

Thanks,
May

Michael_L

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Re: NHD-0108BZ-RN-YBW-33W -- NO display!!
« Reply #2 on: May 01, 2015, 07:46:35 AM »
You mention 4-bit interface works, but you also mention there is nothing on the display; can you please clarify this?
V0 pin should have approx. 0.1V applied to it, but you should wire it as shown in the wiring diagram so it is adjustable.
I am not familiar with using an FPGA to drive it, however our example code is correct, at least when used with CPU software.  Yes, the ascii code for a 1 is 0x31, but you also need to initialize the display, and set the address location of where you want to write to, as shown in the example.

w9001156

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Re: NHD-0108BZ-RN-YBW-33W -- NO display!!
« Reply #3 on: May 01, 2015, 10:03:09 AM »
Hi,

Thanks for you reply.

1) 4-bit interface works. I monitor "rw/rs/e/data" signal by LA.  Read "Busy Flag" is ok, after I write data out, "Address Count" also increase. --> So I guess 4-bit mode works well from this.

2) For V0 voltage, if we just connect 0.1v power at V0 pin, and no adjust resistor on the board, is that ok? --> or Can I change V0 voltage directly 0.1v, 0.2v, 0.3v to try?

3) Yes, I follow init example in the datasheet. The following is my init & write sequence.

    1) Wait >40ms, 0x30 wake up, 0x30 wake up, 0x30 wake up, 0x20 4-bit interface (Wait enough time between steps by following init example)
    2) 0x20 4-bit/1-line display, 0x10 set cursor, 0x0F display on, 0x01, clear display, 0x06 Entry mode. (Checking "Busy Flag" Ready + wait 80us)   (4-bit interface, 2 clock cycle operation)
    3) If write new data out to LCD (I will check "busy flag" before every operation, after every operation, I will wait ~80us)
        A. 0x01 clear display.
        B. Write data0, data1, ..., data7 (for example: "1", "2", ... "8" with 0x31, 0x32, ..., 0x38)

  ==> After writing 8 new data out, i expected that LCD will display "12345678" on the screen, but there is nothing on the screen.
So I don't why this happen. After I finish to write 8x dataout, (Data write into DDRAM), then the data will be auto-read and display on the screen, and LCD will always display the content of DDRAM from address 0x0~0x7, I don't need do any special operation, is this correct?
  ==> After writing 8 new data out, do I need Change DDRAM address count to "0x00" by "Return home" command to display? from your example, I don't need do it.
Please confirm when the new data will be display on the screen? automatic display?
   
 
Thanks for your help!
May



     
« Last Edit: May 01, 2015, 12:29:41 PM by w9001156 »

Michael_L

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Re: NHD-0108BZ-RN-YBW-33W -- NO display!!
« Reply #4 on: May 01, 2015, 04:49:02 PM »
Yes, you may connect 0.1V to V0 without it being adjustable, it is just easy to troubleshoot with an adjustable supply, so you can absolutely rule out not being able to see any characters due to improper contrast voltage.
From what you have said, it seems the 4-bit communication is ok.  Have you tried switching the order of how you send each nibble? (Worth a try)
Otherwise, since the interface seems to be ok, are you able to write to a particular DDRAM location and then read that same location and obtain the character value you wrote?

 

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