firmware_display.ino
#include <inttypes.h>
#include <ctype.h>
#include <SPI.h>
#include <SD.h>
#include "EPD.h"
#include "S5813A.h"
#include "EReader.h"

// the eink related libraries are available from
// https://github.com/wyolum/EPD

int cmd;
char buffer[50];

void setup()
{
    Serial.begin(9600);
    ereader.setup(EPD_2_7);
}

void loop()
{

    if (Serial.available() > 0) {
        memset(buffer, 0, sizeof(buffer));
        cmd = Serial.read();
        Serial.readBytesUntil(0x0a, buffer, 50);
        ereader.spi_attach();
        if (cmd == '1')
            ereader.put_ascii(25, 20, buffer, true);
        else if (cmd == '2')
            ereader.put_ascii(25, 36, buffer, true);
        else if (cmd == '3')
            ereader.put_ascii(25, 52, buffer, true);
        else if (cmd == '4')
            ereader.put_ascii(25, 68, buffer, true);
        else if (cmd == '5')
            ereader.put_ascii(25, 84, buffer, true);
        else if (cmd == '6')
            ereader.put_ascii(25, 100, buffer, true);
        else if (cmd == '7')
            ereader.put_ascii(25, 116, buffer, true);
        else if (cmd == '8')
            ereader.put_ascii(25, 132, buffer, true);
        else if (cmd == '9')
            ereader.put_ascii(25, 148, buffer, true);
        else if (cmd == 'A') {
            ereader.show();
            ereader.spi_detach();       //To avoid screen washout.
        }
    }

}