SE0352NQ01 Library

A library for the SE0352NQ01 e-paper display, driven by a Wisblock RAK4631 (nRF52840 + SX1262). It uses Adafruit GFX fonts for Latin characters, and a vaguely compatible format for Chinese, a subset of 2,500 characters anyway, based on micropython-font-to-py. After running

python3 font_to_py.py -x -k cjk /path/to/font.otf 16 cjk16b.py

I cleaned up cjk16b.py a little, and added code that produces the CJK16pt.h header file. This file can then be included into the Arduino project. The cjk subset file is included, so you can edit it and add/remove chars.

#include <SE0352NQ01.h>
// Include fonts from https://github.com/adafruit/Adafruit-GFX-Library/tree/master/Fonts
#include "FreeSansBold12pt7b.h"
#include "FreeSerifBoldItalic24pt7b.h"
#include "CJK14pt.h"
#include "CJK16ptB.h"

API

    void sleep(void);
    void refresh(void);
    void send(unsigned char*);
    void send_DU(unsigned char*);
    void fill(unsigned char);
    void drawString(char *, uint16_t, uint16_t, GFXfont, uint8_t, unsigned char*);
    void drawUnicode(
      uint16_t*, uint8_t, uint16_t, uint16_t, unsigned char*,
      unsigned char*, uint16_t, uint8_t, uint8_t, unsigned char*
    );
    void drawBitmap(
      uint8_t, uint8_t, uint16_t,
      uint16_t, int8_t, int8_t, // these three only for fonts, not necessary for bitmap images
      uint16_t, unsigned char *, unsigned char *, uint8_t
    ); // fonts version
    void drawBitmap(
      uint8_t, uint8_t, uint16_t,
      uint16_t, unsigned char *, unsigned char *, uint8_t
    ); // bitmap images version
    uint16_t width(uint8_t); // returns width given the orientation
    uint16_t height(uint8_t); // returns height given the orientation

The most important commands are drawString, drawUnicode, and drawBitmap. The first is for ASCII text, the second for Chinese (or other UTF16 codepoints for which you have produced a font), and the third one is for partial images: it is the same code for both images and individual characters, which are both horizontally-encoded bitmaps. I wrote separately a desktop application that creates full-size images, in the RAM buffer format the EPD expects, from pictures you pass it, and partial images encoded as horizontally-encoded bitmaps. These images are resizable with the Zoom slider, and the black-and-white threshold adjustable with the B/W Threshold slider.

The drawString function returns the string's width in pixels, which you can ignore. That is, you can do:

SE0352.drawString((char*)"This is a test", 0, 34, FreeSansBold18pt7b, 0, frame);

uint16_t wd = SE0352.drawString((char*)"This is a test", 0, 34, FreeSansBold18pt7b, 0, frame);

Note that if the string overflows the bottom of the screen (239 or 359 depending on orientation), drawString returns without completing, which means that the returned width will be incorrect. If you're only interested in the string's width, without drawing it, call strWidth().

uint16_t wd = SE0352.strWidth((char*)"This is a test", FreeSansBold18pt7b);

This does basically the same, without drawing anything. It will be accurate too, since the function won't bail because of screen overflow.

The send and send_GU commands send full-size images to the EPD, using either lut_GC() (full refresh) or lut_DU() (faster refresh that may leave shadows if used too often).

This application, EPD Viewer, was made with Xojo, which is a paid development platform. I will release the code, but it'd require Xojo to compile it. I've added in the mean time a binary for Mac OS X, which is what I use. When I can test Linux and Windows version, I will release them too.

Rotation

There are 4 levels of rotation: 0 & 2 (Landscape), and 1 & 3 (Portrait). Rotation is passed to drawString, drawUnicode, and drawBitmap functions every time, so you can draw text in different rotations within the same screen. send and send_GU don't have yet rotation enabled.

Drawing

I have added a few drawing primitives:

void setPixel(uint16_t x, uint16_t y, uint8_t rotation, uint8_t *buffer);
void clearPixel(uint16_t x, uint16_t y, uint8_t rotation, uint8_t *buffer);
void drawHLine(uint16_t x0, uint16_t y0, uint16_t x1, uint8_t rotation, uint8_t *buffer);
void drawVLine(uint16_t x0, uint16_t y0, uint16_t y1, uint8_t rotation, uint8_t *buffer);
void drawLine(uint16_t x0, uint16_t y0, uint16_t x1, uint16_t y1, uint8_t rotation, uint8_t *buffer);
void drawCircle(int xc, int yc, int r, uint8_t rotation, uint8_t *buffer);
void drawRect(uint16_t x0, uint16_t y0, uint16_t x1, uint16_t y1, uint8_t rotation, uint8_t *buffer);
void fillCircle(int xc, int yc, int r, uint8_t rotation, uint8_t *buffer);
void fillRect(uint16_t x0, uint16_t y0, uint16_t x1, uint16_t y1, uint8_t rotation, uint8_t *buffer);
void clearRect(uint16_t x0, uint16_t y0, uint16_t x1, uint16_t y1, uint8_t rotation, uint8_t *buffer);
void drawPolygon(uint16_t * points, uint16_t len, uint8_t rotation, uint8_t *buffer)
void fillContour(uint16_t iXseed, uint16_t iYseed, uint8_t rotation, uint8_t *buffer);

fillContour() works pretty well, but in some cases it may require more than one call. For example, in the image below, fillContour() had to be called twice for the narrow disk: I drew two circles a few pixels apart, then called fillContour() once on the left, and once on the right.

void partialRefresh(uint16_t xStart, uint16_t yStart, uint16_t xEnd, uint16_t yEnd, uint8_t rotation, uint8_t* buffer);

partialRefresh is a bit finicky, but I got it to work pretty well. It too takes care of rotation.

Code128

By popular demand (right...) I have added creation and display of Code128 barcodes.

makeCode128(char *barcode, uint8_t wx, uint8_t bh, uint16_t px, uint16_t py, uint8_t rotation, uint8_t *buffer);

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