Template:E-paper for rpi and jetsonano code description

RaspberryPi and Jetson nano uses the same libraries, as they are compatible with each other in a way.
The codes include bottom hardware interface, middle EPD driver and application;

C

Bottom hardware interface

We package the bottom for different hardware platform.
Most of the interfaces are defined in DEV_Config.c(.h) files:RaspberryPi&JetsonNano\c\lib\Config
Two libraries are used for C codes: BCM2835 and WiringPi
By default, we use WiringPI, if you want to change to BCM2835, you can modify RaspberryPi&JetsonNano\c\Makefile file and modify the line 13 and lin 14 as below:：

• Data type：

#define UBYTE   uint8_t
#define UWORD   uint16_t
#define UDOUBLE uint32_t

• Initialize model and exit:

void DEV_Module_Init(void);
void DEV_Module_Exit(void);

Notice:

1. The functions are used to handle GPIO before initializing the e-Paper and after exiting.
2. If the board you have is printed with Rev2.1, the module enters low-ultra mode after DEV_Module_Exit(). (as we test, the current is about 0 in this mode);

• GPIO Read/Write：

void DEV_Digital_Write(UWORD Pin, UBYTE Value);
UBYTE DEV_Digital_Read(UWORD Pin);

• SPI Write data

void DEV_SPI_WriteByte(UBYTE Value);

Middle EPD driver

The EPD driver are saved in RaspberryPi&JetsonNano\c\lib\e-Paper
Open .h file you can get the functions below

• Initialization: It should be used to initialize e-Paper or wakeup e-Paper from sleep mode.

/2.13inch e-Paper、2.9inch e-Paper
void EPD_xxx_Init(UBYTE Mode); // Mode = 0 Initialize full refresh; Mode = 1 Initilize partial refresh 
//4.2inch e-Paper
void EPD_xxx_Init(void);

xxx is the type of e-paper

• Clear display: This function is used to clear the e-paper to white

void EPD_xxx_Clear(void); 

xxx is the type of e-paper, for example, if the e-paper is 2.13inch e-paper, it should be EPD_2IN13_V2_Clear(); if it is 2.9inch e-paper, it should be EPD_2IN9_Clear()

• Transmit a frame of image and display

//Blac/White e-Paper
void EPD_xxx_Display(UBYTE *Image);
//Three colors e-Paper
void EPD_xxx_Display(const UBYTE *blackimage, const UBYTE *ryimage);

// To partial refresh the 2.13inch e-paper, you should firstly use EPD_xxx_DisplayPartBaseImage function to display background, and then partial refresh by function EPD_xxx_DisplayPart()
void EPD_2IN13_V2_DisplayPart(UBYTE *Image);
void EPD_2IN13_V2_DisplayPartBaseImage(UBYTE *Image);

• Enter sleep mode

void EPD_xxx_Sleep(void);

You should hardware reset or use initialize function to wake up e-Paper from sleep mode
xxx is the type of e-Paper, if it is 2.13, you should use EPD_2IN13_V2_Sleep()

Application functions

Basic drawing functions are provided here. You can find then in: Raspbian Pi & Jetson Nano: RaspberryPi&JetsonNano\c\lib\GUI\GUI_Paint.c(.h)

The fonts are saved in the directory: Raspberry Pi & Jetson Nano: RaspberryPi&JetsonNano\c\lib\Fonts

• Create a new image buffer: This function is used to create a new image with width, height, Rotate degree and its color.

void Paint_NewImage(UBYTE *image, UWORD Width, UWORD Height, UWORD Rotate, UWORD Color)
Parameters:
 	image: The buffer of the image, this is a pointer of buffer address;
 	Width: width of the image;
 	Height: Height of the image;
 	Rotate: Rotate degree;
 	Color: Initial color of the image;

• Select image buffer: this function is used to select the image buffer. You can create multiple image buffer with last function, then select the buffer for every image.

void Paint_SelectImage(UBYTE *image)
Parameters:
 	image: The name of image buffer, it is a pointer of buffer address;

• Set display orientation: This function is used to set the rotate degree, it is generally be used after Paint_SelectImage(). You can set the rotate degree to 0、90、180、270 degree.

void Paint_SetRotate(UWORD Rotate)
Parameters:
 	Rotate: Rotate degree, you can choose ROTATE_0、ROTATE_90、ROTATE_180、ROTATE_270 which stands for 0、90、180、270 degree repetitively.

• Image mirroring: This function is used to mirror image.

void Paint_SetMirroring(UBYTE mirror)
Parameters:
 	mirror: You can set it to MIRROR_NONE、MIRROR_HORIZONTAL、MIRROR_VERTICAL、MIRROR_ORIGIN

et pixel: this function is used to set the position and color of pixels in the buffer. This is the basic function of GUI.

void Paint_SetPixel(UWORD Xpoint, UWORD Ypoint, UWORD Color)
Parameters:
 	Xpoint: X-axes in buffer;
 	Ypoint: Y-axes in buffer;
 	Color : color

• Clear: This function is used to clear the screen to certain color.

void Paint_Clear(UWORD Color)
Parameters:
 	Color: 

• Clear windows:this function is used to clear a window. It is generally used for time display.

void Paint_ClearWindows(UWORD Xstart, UWORD Ystart, UWORD Xend, UWORD Yend, UWORD Color)
Parameters:
 	Xstart: Start coordinate of X-axes of the window;
 	Ystart: Start coordinate of Y-axes of the window;
 	Xend: End coordinate of X-axes of the window;
 	Yend: End coordinate of Y-axes of the window;
 	Color: 

• Draw point: Draw a point on the position （Xpoint, Ypoint）in buffer

void Paint_DrawPoint(UWORD Xpoint, UWORD Ypoint, UWORD Color, DOT_PIXEL Dot_Pixel, DOT_STYLE Dot_Style)
Parameters:
 	Xpoint: X coordinate of point;
 	Ypoint: Y coordinate of point;
 	Color: color of point;
 	Dot_Pixel: the size of point, there are 8 sizes available;
 	 	 typedef enum {
 	 	 	 DOT_PIXEL_1X1  = 1,	// 1 x 1
 	 	 	 DOT_PIXEL_2X2  , 		// 2 X 2
 	 	 	 DOT_PIXEL_3X3  , 	 	// 3 X 3
 	 	 	 DOT_PIXEL_4X4  , 	 	// 4 X 4
 	 	 	 DOT_PIXEL_5X5  , 		// 5 X 5
 	 	 	 DOT_PIXEL_6X6  , 		// 6 X 6
 	 	 	 DOT_PIXEL_7X7  , 		// 7 X 7
 	 	 	 DOT_PIXEL_8X8  , 		// 8 X 8
 	 	} DOT_PIXEL;
 	Dot_Style: style of point. 
 	 	typedef enum {
 	 	   DOT_FILL_AROUND  = 1,		
 	 	   DOT_FILL_RIGHTUP,
 	 	} DOT_STYLE;

• Draw line: draw a line for (Xstart, Ystart) to (Xend, Yend)

void Paint_DrawLine(UWORD Xstart, UWORD Ystart, UWORD Xend, UWORD Yend, UWORD Color, LINE_STYLE Line_Style , LINE_STYLE Line_Style)
Parameters:
 	Xstart: Start coordinate of X-axes of line;
 	Ystart: Start coordinate of Y-axes of line;
 	Xend: End coordinate of X-axes of line;
 	Yend: End coordinate of Y-axes of line;
 	Color: color of line
 	Line_width: the width of line, 8 sizes are avalilable;
 	 	typedef enum {
 	 	 	 DOT_PIXEL_1X1  = 1,	// 1 x 1
 	 	 	 DOT_PIXEL_2X2  , 		// 2 X 2
 	 	 	 DOT_PIXEL_3X3  ,		// 3 X 3
 	 	 	 DOT_PIXEL_4X4  ,		// 4 X 4
 	 	 	 DOT_PIXEL_5X5  , 		// 5 X 5
 	 	 	 DOT_PIXEL_6X6  , 		// 6 X 6
 	 	 	 DOT_PIXEL_7X7  , 		// 7 X 7
 	 	 	 DOT_PIXEL_8X8  , 		// 8 X 8
 	 	} DOT_PIXEL;
 	 Line_Style:Style of the line;
 	 	typedef enum {
 	 	 	 LINE_STYLE_SOLID = 0,
 	 	 	 LINE_STYLE_DOTTED,
 	 	} LINE_STYLE;

• Draw rectangle: Draw a rectangle from (Xstart, Ystart) to (Xend, Yend).

void Paint_DrawRectangle(UWORD Xstart, UWORD Ystart, UWORD Xend, UWORD Yend, UWORD Color, DOT_PIXEL Line_width, DRAW_FILL Draw_Fill)
Parameters:
 	Xstart: Start coordinate of X-axes of rectangle
 	Ystart: Start coordinate of Y-axes of rectangle
 	Xend: End coordinate of X-end of rectangle
 	Yend: End coordinate of Y-end of rectangle
 	Color: color of rectangle
 	Line_width: The width of edges, 8 sides are available;
 	 	typedef enum {
 	 	 	 DOT_PIXEL_1X1  = 1,	// 1 x 1
 	 	 	 DOT_PIXEL_2X2  , 		// 2 X 2
 	 	 	 DOT_PIXEL_3X3  ,		// 3 X 3
 	 	 	 DOT_PIXEL_4X4  ,		// 4 X 4
 	 	 	 DOT_PIXEL_5X5  , 		// 5 X 5
 	 	 	 DOT_PIXEL_6X6  , 		// 6 X 6
 	 	 	 DOT_PIXEL_7X7  , 		// 7 X 7
 	 	 	 DOT_PIXEL_8X8  , 		// 8 X 8
 	 	} DOT_PIXEL;
 	Draw_Fill: set the rectangle full or empty.
 	 	typedef enum {
 	 	 	 DRAW_FILL_EMPTY = 0,
 	 	 	 DRAW_FILL_FULL,
 	 	} DRAW_FILL;

• Draw circle:Draw a circle, use (X_Center Y_Center) as center;

void Paint_DrawCircle(UWORD X_Center, UWORD Y_Center, UWORD Radius, UWORD Color, DOT_PIXEL Line_width, DRAW_FILL Draw_Fill)
Parameters:
 	X_Center: X coordinate of center
 	Y_Center: Y coordinate of center
 	Radius：Radius of circle
 	Color: color of circle
 	Line_width: width of circle, 8 sizes are avalilable
 	 	typedef enum {
 	 	 	 DOT_PIXEL_1X1  = 1,	// 1 x 1
 	 	 	 DOT_PIXEL_2X2  , 		// 2 X 2
 	 	 	 DOT_PIXEL_3X3  ,		// 3 X 3
 	 	 	 DOT_PIXEL_4X4  ,		// 4 X 4
 	 	 	 DOT_PIXEL_5X5  , 		// 5 X 5
 	 	 	 DOT_PIXEL_6X6  , 		// 6 X 6
 	 	 	 DOT_PIXEL_7X7  , 		// 7 X 7
 	 	 	 DOT_PIXEL_8X8  , 		// 8 X 8
 	 	} DOT_PIXEL;
 	Draw_Fill: style of circle
 	 	typedef enum {
 	 	 	 DRAW_FILL_EMPTY = 0,
 	 	 	 DRAW_FILL_FULL,
 	 	} DRAW_FILL;

• Draw character (ASCII): Set(Xstart Ystart) as letf-top point, draw a ASCII character.

void Paint_DrawChar(UWORD Xstart, UWORD Ystart, const char Ascii_Char, sFONT* Font, UWORD Color_Foreground, UWORD Color_Background)
Parameters:
 	Xstart: X coordinate of left-top pixel of character;
 	Ystart: Y coordinate of left-top pixel of character;
 	Ascii_Char：Ascii character;
 	Font: 5 fonts are available;
 	 	font8：5*8
 	 	font12：7*12
 	 	font16：11*16
 	 	font20：14*20
 	 	font24：17*24
 	Color_Foreground: color of character;
 	Color_Background: color of background;

• Draw String: Set point (Xstart Ystart) as the left-top pixel, draw a string.

void Paint_DrawString_EN(UWORD Xstart, UWORD Ystart, const char * pString, sFONT* Font, UWORD Color_Foreground, UWORD Color_Background)
Parameters:
 	Xstart: X coordinate of left-top pixel of characters;
 	Ystart: Y coordinate of left-top pixel of characters;
 	pString：Pointer of string
 	Font: 5 fonts are available:
 	 	font8：5*8
 	 	font12：7*12
 	 	font16：11*16
 	 	font20：14*20
 	 	font24：17*24
 	Color_Foreground: color of string
 	Color_Background: color of background

• Draw Chinese charactgers: this function is used to draw Chinese fonts based ON GB2312 fonts.

void Paint_DrawString_CN(UWORD Xstart, UWORD Ystart, const char * pString, cFONT* font, UWORD Color_Foreground, UWORD Color_Background)
Parameters:
 	Xstart: Coordinate of left-top pixel of characters;
 	Ystart: Coordinate of left-top pixel of characters;
 	pString：Pointer of string;
 	Font: GB2312 fonts：
 	 	font12CN：11*21(ascii)，16*21 (Chinese)
 	 	font24CN：24*41(ascii)，32*41 (Chinese)
 	Color_Foreground: color of string
 	Color_Background: color of background

• Draw number: Draw a string of numbers, (Xstart, Ystart) is the left-top pixel.

void Paint_DrawNum(UWORD Xpoint, UWORD Ypoint, int32_t Nummber, sFONT* Font, UWORD Color_Foreground, UWORD Color_Background)
Parameters:
 	Xstart: X coordinate of left-top pixel;
 	Ystart: Y coordicate of left-to pixel;
 	Nummber: the numbers displayed. the numbers are saved in int format, the maximum is 2147483647;
 	Font: 5 fonts are available：
 	 	font8：5*8
 	 	font12：7*12
 	 	font16：11*16
 	 	font20：14*20
 	 	font24：17*24
 	Color_Foreground: color of font;
 	Color_Background: volor of background;

• Display time:Display time, (Xstart, Ystart) is the left-top pixel. This function is used for e-Paper which supports partial refresh

void Paint_DrawTime(UWORD Xstart, UWORD Ystart, PAINT_TIME *pTime, sFONT* Font, UWORD Color_Background, UWORD Color_Foreground)
Parameters:
 	Xstart: X coordinate of left-top pixel of character;
 	Ystart: Y coordinate of left-top pixel of character;
 	pTime：pointer of time displayed;
 	Font: 5 fonts are available;
 	 	font8：5*8
 	 	font12：7*12
 	 	font16：11*16
 	 	font20：14*20
 	 	font24：17*24
 	Color_Foreground: color of fonts
 	Color_Background: color of background

• Draw image:send image data of bmp file to buffer

void Paint_DrawBitMap(const unsigned char* image_buffer)
Parameters:
 	image_buffer: adrress of image data in buffer

• Read local bmp picture and write it to buffer

Linux platform like Jetson Nano and Raspberry Pi support to directly operate bmp pictures
Raspberry Pi & Jetson Nano：RaspberryPi&JetsonNano\c\lib\GUI\GUI_BMPfile.c(.h)

UBYTE GUI_ReadBmp(const char *path, UWORD Xstart, UWORD Ystart)
Parameters:
	path：The path of BMP pictures
 	Xstart: X coordination of left-top of picture, default 0;
 	Ystart: Y coordination of left-top of picture, default 0;

Testing code

In the above part, we describe the tree structures of Linux codes, here we talk about the testing code for user.
Raspberry Pi & Jetson Nano: RaspberryPi&JetsonNano\c\examples. The codes in examples are testing code, you can modify the definition in main.c file for different types of e-Paper.

For example, if you want to test 2.13inch e-paper, you need to delete the "//" symbol on line 32.

// EPD_2in13_V2_test();

Change it to

EPD_2in13_V2_test();

Then compile it again and run

make clean
make
sudo ./epd

Python(Can be used for Jetson Nano\Raspberry Pi)

It is compatible with python2.7 and python3
对于python而言他的调用没有C复杂
Raspberry Pi和Jetson Nano：RaspberryPi&JetsonNano\python\lib\

epdconfig.py

• 模块初始化与退出的处理：

def module_init()
def module_exit()
 注意：
 1.这里是处理使用墨水屏前与使用完之后一些GPIO的处理。
 2.对于PCB带有Rev2.1的，module_exit()之后整个模块会进入低功耗，经过测试这个功耗基本为0;

• GPIO读写：

def  digital_write(pin, value)
def  digital_read(pin)

• SPI写数据

def spi_writebyte(data)

epdxxx.py(xxx表示尺寸，若是2.13inch e-paper，则为epd2in13.py,依此类推)

• 墨水屏初始化，再屏幕开始工作时和退出睡眠模式之后调用

对于2.13inch e-Paper、2.9inch e-Paper
def init(self, update) # 选择lut_full_update或lut_partial_update
其他型号
def init(self)

• 清屏，把墨水屏刷成白色

def Clear(self)
def Clear(self, color) # 对于某几个屏幕需要调用这个

• 把图片转换成数组

def getbuffer(self, image)

• 传输一帧的图片数据并打开显示

黑白双色墨水屏
def display(self, image)


对于2.13inch e-paper由于控制芯片升级，对于局部刷新,需要调用displayPartBaseImage()显示静态的背景图片，也就是以这个图片为基础进行局部刷新，然后调用动态的displayPart()
def displayPartBaseImage(self, image)
def displayPart(self, image)

• 进入睡眠模式

def sleep(self)

epd_xxx_test.py(xxx表示尺寸，若是2.13inch e-paper，则为epd_2in13_V2_test.py,依此类推)

python在如下目录：
Raspberry Pi和Jetson Nano：RaspberryPi&JetsonNano\python\examples\

如果你的python版本是python2，且需要运行2.13inch e-paper测试程序，在linux命令模式下重新执行如下：

sudo python epd_2in13_V2_test.py

如果你的python版本是python3，且需要运行2.13inch e-paper测试程序，在linux命令模式下重新执行如下：

sudo python3 epd_2in13-V2_test.py

关于旋转设置

如果在python程序中你需要设置屏幕旋转，可以通过语句blackimage = blackimage.transpose(Image.ROTATE_270)设置。

blackimage = blackimage.transpose(Image.ROTATE_270) 
redimage = redimage.transpose(Image.ROTATE_270)
#支持ROTATE_90, ROTATE_180, ROTATE_270三个参数

画图GUI

由于python有一个image库pil官方库链接，他十分的强大，不需要像C从逻辑层出发编写代码，可以直接引用image库进行图像处理，以下将以1.54inch e-paper为例，对程序中使用了的进行简要说明

• 需要使用image库，需要安装库

sudo apt-get install python3-pil  安装库

然后导入库

from PIL import Image,ImageDraw,ImageFont

其中Image为基本库、ImageDraw为画图功能、ImageFont为文字

• 定义一个图像缓存，以方便在图片上进行画图、写字等功能

image = Image.new('1', (epd.width, epd.height), 255)  # 255: clear the frame

第一个参数定义图片的颜色深度，定义为1说明是2位图，第二个参数是一个元组，定义好图片的宽度和高度，第三个参数是定义缓存的默认颜色，0为黑色，255为白色。

• 创建一个基于image的画图对象，所有的画图操作都在这个对象上

draw = ImageDraw.Draw(image)

• 画框

draw.rectangle((0, 10, 200, 34), fill = 0)

第一个参数为一个4个元素的元组，（0，10）矩形左上角坐标值，（200，34）为矩形右下角坐标值，fill=0表示内部填充黑色。

• 画线

draw.line((16, 60, 56, 60), fill = 0)

第一个参数为一个4个元素的元组，以（16，60）为起始点，（200，34）为终止点，画一条直线，fill=0表示线为黑色。

• 画圆

draw.arc((90, 60, 150, 120), 0, 360, fill = 0)

在正方形内画一个内切圆，第一个参数为一个4个元素的元组，以（90，60）为正方形的左上角顶点，（150，120）为正方形右下角顶点，规定矩形框的水平中位线为0度角，角度顺时针变大，第二个参数表示开始角度，第三个参数标识结束角度，fill=0线为黑色
如果不是正方形，画出来的就是椭圆，这个实际上是圆弧的绘制。

除了arc可以话圆之外，还有chord可以画实心圆

draw.chord((90, 130, 150, 190), 0, 360, fill = 0)

实质是弦的绘制，第一个参数指定弦的圆外切矩形，第二、三两个参数分别是弦的起始和终止角度， 第四个参数是填充颜色，将弦从0度到360度连接并填充就变成了填充的圆了。

• 写字符

写字符往往需要写不同大小的字符，需要导入ImageFont模块，并实例化：

font = ImageFont.truetype(os.path.join(picdir, 'Font.ttc'), 24)

为了丰富字体库，这里使用的是windows目录下的字符文件，如果是其他的ttc结尾的字符文件也是支持的。

写英文字符直接使用即可，写中文，由于编码是GB2312所以需要在前面加个u：

draw.text((8, 12), 'hello world', font = font, fill = 255)
draw.text((8, 36), u'电子墨水屏', font = font, fill = 0)

第一个参数为一个2个元素的元组，以（8，12）为左顶点，字体为font，点，fill为字体颜色，第一句fill=255所以看上去是不会显示的，第二句显示微雪电子。

• 读取本地图片

image = Image.open(os.path.join(picdir, '2in13-v2.bmp'))

参数为图片路径。

• 其他功能

python的image库十分强大，如果需要实现其他的更多功能，可以上官网学习http://effbot.org/imagingbook pil，官方的是英文的，如果感觉对你不友好，当然我们国内也有很多的优秀的博客都有讲解。