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81
OLEDs / How to reset NHD-0216SZW-BY5?
« Last post by a_horst on April 06, 2018, 08:25:11 AM »
Hi guys,
I got a NHD-0216SZW-BY5 connected to a Arduino similar board and use the LiquidCrystal library like in your example code.
Basically i have no troubles to get output on the screen. Only when i reset, upload new code or plug out and in the supply too fast, it starts writing at the wrong position and/or magic numbers.

Due to this I guess the content in the RAMs is not lost fast enough.

So my question now would be - what commands would I have to send initially to the controller to avoid this?

Thanks already in advance for every helpful though/answer. :)
82
Customer Projects / Re: New Support library for FTDI Screen Newhaven Display
« Last post by lightcalamar on April 05, 2018, 12:44:08 PM »
My latest video recently released new 7-inch display of NHD with ESP32, model display  NHD-7.0-800480FT-CSXN-CTP :

https://youtu.be/c25QPZd90YM
83
TFTs / Re: SPI problem with NHD-3.5-320240FT-CSXN-CTP
« Last post by Wiggum on April 05, 2018, 12:42:37 PM »
Hi Ted,

sure. Have a look at my initial posting.

I had to reduce the power supply to 2.9V to run stable.

Best regards,

Rainer
84
TFTs / Re: SPI problem with NHD-3.5-320240FT-CSXN-CTP
« Last post by Ted_M on April 05, 2018, 11:57:37 AM »
Hi Rainer,

Unfortunately we have not tested this using an MPSSE interface.  If you find any issues using this type of interface, please report them here for us to help.
         
85
TFTs / Re: Display Font related issue
« Last post by darshana somarajan on April 05, 2018, 05:00:09 AM »
Sir,
Sorry for the delay as I was mapped to some other work and now I am back to the loop, I am using bitmap format
Arial Narrow 14pts W
const uint_8 arialNarrow_14ptBitmaps[] =
{
   // @0 'W' (13 pixels wide)
   0x82, 0x08, // #     #     #
   0x82, 0x08, // #     #     #
   0x85, 0x08, // #    # #    #
   0x85, 0x08, // #    # #    #
   0x85, 0x08, // #    # #    #
   0x48, 0x90, //  #  #   #  #
   0x48, 0x90, //  #  #   #  #
   0x48, 0x90, //  #  #   #  #
   0x48, 0xD0, //  #  #   ## #
   0x50, 0x50, //  # #     # #
   0x50, 0x50, //  # #     # #
   0x50, 0x50, //  # #     # #
   0x20, 0x20, //   #       # 
   0x20, 0x20, //   #       # 
};
86
TFTs / Re: SPI problem with NHD-3.5-320240FT-CSXN-CTP
« Last post by Wiggum on April 05, 2018, 02:39:31 AM »
Hi Ted,

BTW: Did you ever test the MPSSE cable communication?
Your example projects on github are only configured to your modules correctly for the Arduino platform.

Best regards,

Rainer
87
I think I figured this all out.  Basically the PNP transistor is an emitter follower used to provide a low-source-impedance for the "GND" supply pin of the quad op-amp which buffers a 5-resistor divider for the LCD bias voltages!  It also directly provides one of the bias voltages to the 4 LCD driver ICs.  Here is a pic of the updated schematic:

https://drive.google.com/file/d/1PqlK9YAYjldn9mCpSbASfeHmY1gFXlMD/view?usp=sharing

As I see it, there is no great re-population option using the existing pads.  I'm not a fan of adding resistance in series with op-amp supply pins, but especially in this case where the op-amp current over temperature may change the static bias condition which may have a noticeable affect on the contrast ... but it might be ok ... I just haven't tested it either way.  Another possibility I've considered is to add a resistor between the PNP base and VEE as there are pads that would allow for easy component placement, however this may have the same bias current issue (maybe worse?).

It seems as though one of the manufacturer's intended options would be to remove the transistor, 0Ω jumper R81, and replace R6 with some resistance that would achieve the desired contrast, again with the op-amp bias current "potential issue".

All of that said, eliminating the op-amp bias current as a source of variability would be as easy as connecting the GND pin directly to VEE after disconnecting it from the resistor divider.  Since the supply delta would be higher than it "needs" to be, I suppose there may be more heat generated, but again, I haven't tested that.  Note that the V5 connections of the LCD drivers still need to maintain this connection for proper LCD bias.

Again, if anyone has any results related to the options above or others, please share!!!

Below are links to the PNP transistor (2SB1198K), the quad op-amp (AS324M) and the LCD driver (NT7086PQ).  Though not in my schematic, I have also included the datasheet for the MCU interface (RA6963):

2SB1198K
https://www.rohm.com/datasheet/2SB1198K/2sb1198k

AS324M
https://www.diodes.com/assets/Datasheets/AS324_A.pdf

NT7086PQ
https://www.crystalfontz.com/controllers/NT7086.pdf

RA6963
https://www.newhavendisplay.com/app_notes/RA6963.pdf
88
TFTs / Re: SPI problem with NHD-3.5-320240FT-CSXN-CTP
« Last post by Ted_M on April 04, 2018, 12:00:22 PM »
Hi Rainer,

The added buffers (74LCX125) on the FTDI board allow the SPI master and slave interface of the FT8xx to be 5v tolerant. 
Our board will support the 3.3v SPI interface and is not 5v tolerant. Thanks for your input and let us know what you find.

Best Regards,
Ted
89
TFTs / Re: SPI problem with NHD-3.5-320240FT-CSXN-CTP
« Last post by Wiggum on April 04, 2018, 10:42:51 AM »
Hi Ted,


thanks for your response. The MPSSE cable can indeed not drive the current. That's why I am using an external power supply (connecting the GNDs, of course).
With that, I was able to reduce the supply voltage to 2.9V and see that it works, there.

The MPSSE is not my main concern. It is our custom board with the Tiva processor.
Comparing the NHD circuit with that on the VM800 board by FTDI, I see buffers (74LCX125) on the FTDI board which are not used on the NHD board.
I am suspecting that it's the SPI communication.
As said, the FTDI display works flawlessly in all our configurations.

I am digging into this and will report but would appreciate any hint.

Best regards,

Rainer

90
TFTs / Re: SPI problem with NHD-3.5-320240FT-CSXN-CTP
« Last post by Ted_M on April 04, 2018, 10:11:03 AM »
Hi Rainer,

The MPSSE cable may not supply enough current to drive the display and the backlight on it's own.  Please describe how the display is receiving power in your configuration. 

Try connecting this display to an Arduino using our NHD-FT81x-SHIELD for easier prototyping.  It has a built in Buck regulator that will supply the proper power to the display and also drive the backlight.

http://www.newhavendisplay.com/userguides/NHD-FT81x-SHIELD_User_Guide.pdf

Best Regards,
Ted
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