9 years, 4 months ago.

EPD Extension Board with older EM027AS012 display compatibility

Hi, I have one of the EPD Extension Boards (http://repaper.org/doc/extension_board.html#pin-assignment) and the older, now obsolete e-ink panel mounted to it (EM027AS012). I notice from other threads that luckily for me this older panel is what the EaEpaper library wants to work with.

The main thing the EPD board has different to theEmbedded Artists AB board seems to be that it uses a different temperature sensor. The EaEpaper class calls setFactor(readTemperature()/100) so I have tried various hard coded values for readTemperature ranging from 10*100 to 25*100. This gives EPD.setFactor a somewhat reasonable value for temperature in deg C. If I can get things working then obviously doing something more in readTemperature() would be a better choice... anyway...

After some tinkering I can get it to display a single image (single write_disp() call) but when an addition or clear is attempted after that then the screen slowly fades darker in a non uniform way. I am using an ST Nucleo F401RE (100kb ram) so the MCU shouldn't have any problem resource wise.

I have pulled the flash_cs pin high to avoid it getting in the way of the epd-cs pin in any way. Any thoughts on what I might try next would be great.

epaper board  | 401 board | desc       | EaEpaper-ctor()       | EPD_Class
--------------+-----------+------------+-----------------------+---------------
           1  | 3v3       | power      | .                     |
           7  | 13        | spi-clk    | SPI_SCK     clk       |
           8  |  8        | busy       | BUSY        busy      | EPD_Pin_BUSY
           9  |  3        | pwm        | PWM         pwm       | EPD_Pin_PWM
          10  |  7        | reset      | RESET_DISP  reset     | EPD_Pin_RESET
          11  |  4        | panel-on   | PWR_CTRL    p_on      | EPD_Pin_PANEL_ON
          12  |  6        | discharge  | DISCHARGE   discharge | EPD_Pin_DISCHARGE
          13  |  5        | border-ctl | BORDER      border    | EPD_Pin_BORDER
          14  | 12        | spi-miso   | SPI_MISO    miso      |
          15  | 11        | spi-mosi   | SPI_MOSI    mosi      |
          16  |           |            |                       |
          17  |           |            |                       |
          18  | high      | flash-cs   | .                     |
          19  | 10        | epd-cs     | SSEL        cs        | EPD_Pin_EPD_CS
          20  | gnd       | gnd        | .                     |

EaEpaper epaper(D4,                 // PWR_CTRL
                D5,                 // BORDER
                D6,                 // DISCHARGE
                D7,                 // RESET_DISP
                D8,                 // BUSY
                D10,                // SSEL
                PWM_OUT,            // PWM
                SPI_MOSI,SPI_MISO,SPI_SCK,  // MOSI,MISO,SCLK
                I2C_SDA,I2C_SCL);   // SDA,SCL

int main()
{

    epaper.cls();                                  // clear screen
    epaper.set_font((unsigned char*) Arial28x28);  // select the font
    epaper.locate(5,20);                           // set cursor
    epaper.printf("Hello Mbed");                   // print text
    epaper.rect(3,15,150,50,1);                    // draw frame
    epaper.locate(15,80);                          // set cursor
    epaper.printf("hi!");                          // print text
    epaper.write_disp();                           // update screen

    for(int i=0; ; i++ ) {
        wait(5);

         // anything I do here that ends in an attempt to update the display
         // doesn't work
#if 0
        epaper.cls();
        epaper.write_disp();  
        wait(5);
#endif
        
        epaper.circle(160,150,20,1); 
//        epaper.cls();                                  // clear screen
        epaper.set_font((unsigned char*) Arial28x28);  // select the font
        epaper.locate(15,80);                          // set cursor
        epaper.printf("hi! %d",i);                    // print text
        epaper.write_disp();                           // update screen

    }
    return 0;
}

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Last updated: 25 Jun 2014

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