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Messages - cherry8wild

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OLEDs / Re: NHD 2.7 Screen Image Streaking
« on: August 07, 2014, 11:30:16 AM »
Yea, taking pictures of the screens isn't easy. I'll go through the code and see if I see anywhere I am missing something. Thanks again, and hopefully my screen will look like that soon!

OLEDs / Re: NHD 2.7 Screen Image Streaking
« on: August 05, 2014, 06:24:56 PM »
Hello again,

Here is an update on what I have tried and the results of those attempts.

1. Changing Display

I got another identical display, but it did the same thing.

2. Changing the controller

I also have used an Arduino Mega 2560 to run the display. This was running completely different code than the Microchip controller, but the same initialization sequence. Same results.

3. Different values for Initalization.

I have programmed the displays to cycle through various initialization parameters, specifically the contrast current, contrast current range, precharge compensation, precharge voltage, and the VcomH voltage. I was able to observe the changes in the display but none of them ever removed the lines completely.

The best Screen image has been when I use :

Current Range: 0x86
Contrast Current: 0x3F
Precharge Compensation: 0x02
Precharge Voltage: 0x10

this is seen in the image "Menu Navigation". However, the same settings with a display screen which is not as full yields the same streaking lines. The displays also look best when the majority of the screen is on. When there are only a few pixels on, it becomes worse.

4. As for the Display offset, I actually need to use that functionality of this display, but even when it is zero, the streaks occur.

Any more thoughts?

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OLEDs / Re: NHD 2.7 Screen Image Streaking
« on: July 22, 2014, 10:03:43 AM »
We are going to order another display to test, but for now since it works other than the streaking, we are going to continue using it for development. Have you seen this behavior before?

We analyzed the signals going to the display yesterday using a logic analyzer and the display is getting the correct initialization.

OLEDs / Re: NHD 2.7 Screen Image Streaking
« on: July 21, 2014, 12:03:23 PM »
Measured, the display is getting 3.295V, and unfortunately we do not have another display to try.

OLEDs / Re: NHD 2.7 Screen Image Streaking
« on: July 21, 2014, 11:57:24 AM »
Good catch, you are correct. Unfortunately, no change in the display. :/

(Updated the code for future users)

OLEDs / Re: NHD 2.7 Screen Image Streaking
« on: July 21, 2014, 11:43:05 AM »

The values I was using for the Initialization were slightly different, but the same streaking occurs with the new values as well. Here is the initialization function I am using, if there is still anything wrong.

Code: [Select]
void OLED_12864_Init_test()
    TRIS_RS =   0;
    TRIS_SCLK = 0;
    TRIS_CS =   0;
    TRIS_SDIN = 0;

    SSPCON1bits.SSPEN = 0;
    SSPSTATbits.SMP = 1; // SPI Master Mode
    SSPSTATbits.CKE = 1;
    SSPCON1bits.SSPM3 = 0;
    SSPCON1bits.SSPM2 = 0;
    SSPCON1bits.SSPM1 = 0;
    SSPCON1bits.SSPM0 = 0;

    SSPCON1bits.SSPEN = 1;

    LAT_CS = 1;

    LAT_RS = 0;
    LAT_RS = 1;

    SPI_Write1(0xAE); // Set display OFF

    SPI_Write1(0xB3); // Set Display Clock

    SPI_Write1(0xA8); // Set Multiplex Ratio

    SPI_Write1(0xA2); // Set Display Offset

    SPI_Write1(0xA1); // Start Line

    SPI_Write1(0xAD); // Set Master Configuration

    SPI_Write1(0xA0); // Set Remap Format

    SPI_Write1(0x84); // Set Current Range (1/4)

    SPI_Write1(0xB8); // Set Greyscale Table

    SPI_Write1(0x81); // Set Contranst Current

    SPI_Write1(0xB2); // Set Row Period (Frame Frequency)

    SPI_Write1(0xB1); // Set Phase Length

    SPI_Write1(0xBC); // Set Precharge Voltage

    SPI_Write1(0xB4); // Set Precharge Compensation

    SPI_Write1(0xB0); // Set Precharge Enable

    SPI_Write1(0xBE); // Set V_com_H Voltage level

    SPI_Write1(0xBF); // Set Segment Low voltage

    SPI_Write1(0xA4); //Set Display Mode Normal

    SPI_Write1(0xAF); // Set Display On
Also, the wiring diagram and the hardware setup. I have a very basic setup, pretty much taken straight from the NHD data sheet. Any suggestions appreciated! Screen is very clear and easy to read, but the streaking lines are not acceptable for my application.

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OLEDs / Re: NHD 2.7 Screen Image Streaking
« on: July 21, 2014, 10:30:08 AM »
Alright, Thanks. I'll try those values out.

OLEDs / NHD 2.7 Screen Image Streaking
« on: July 17, 2014, 12:20:33 PM »

I am currently working on a project using a Newhaven 2.7" OLED Graphic display. I have a problem with the screen Images turning out poorly. when some pixels in a column are on, the whole column glows (at different intensities based on the number of pixels that are on). In all of the photos, the screen is cleared, and written over as all pixels OFF, before any ON pixels are written.

Any thoughts?

Display - NHD‐2.7‐12864UCY3
Interface - SPI

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