目次
はじめに
今回は、2.13インチ電子ペーパーディスプレイ（250×122）をRaspberry Pi Picoと組み合わせて使ってみました。
紙のように見えるこのディスプレイは、電源が切れても表示を保持できるというユニークな特徴を持っています。
本記事では、このモジュールの仕組みと使い方を解説します。
リンク
電子ペーパーとは？特長と仕組み
電子ペーパー（E-Ink）は、微細なカプセルの中に入った黒と白の粒子を電圧で制御することで表示を行います。
主な特徴は以下のとおりです
| 特徴 | 説明 |
| 表示維持 | 電源を切っても表示内容が保持される |
| 消費電力 | 更新時以外はほぼゼロに近い |
| 視認性 | 紙のような読みやすさ。太陽光下でも見やすい |
| 表示速度 | 通常の液晶より遅い（更新に数秒） |
仕組み上、動画や高速な描画には向いていませんが、「一度表示すれば長時間そのままにしたい」用途には最適です
配線方法とPicoとの接続例
今回紹介しているモジュールは差すだけでOKです
| Raspberry Pi Pico | e-Paper |
| 3V3 | Vcc |
| GND | GND |
| GP11 | DIN |
| GP10 | CLK |
| GP9 | CS |
| GP18 | DC |
| GP12 | RST |
| GP13 | BUSY |
e-Paperを使ってみる
GitHubに表示用のライブラリがありますので、活用させていただきます。
Pico-epaper-●.●_▲.py がたくさんありますが、ご自身のものに合わせてください。
「●.●」はインチサイズです。
「▲」はePaperのバージョンです。本体にシールなどが貼ってあるとおもわれます。
（私はV4というシールがありました。
「-（ハイフン）」や「.（ピリオド？小数点?)」が使用されていますが、できるだけ使わないほうがよいものになります。リネームして使いましょう。
DLしたファイルを、Pico_ePaper_213_V4.py とリネームしてPicoに保存
from machine import Pin, SPI
import framebuf
import utime
EPD_WIDTH = 122
EPD_HEIGHT = 250
RST_PIN = 12
DC_PIN = 8
CS_PIN = 9
BUSY_PIN = 13
class EPD_2in13_V4_Portrait(framebuf.FrameBuffer):
def __init__(self):
self.reset_pin = Pin(RST_PIN, Pin.OUT)
self.busy_pin = Pin(BUSY_PIN, Pin.IN, Pin.PULL_UP)
self.cs_pin = Pin(CS_PIN, Pin.OUT)
if EPD_WIDTH % 8 == 0:
self.width = EPD_WIDTH
else :
self.width = (EPD_WIDTH // 8) * 8 + 8
self.height = EPD_HEIGHT
self.spi = SPI(1)
self.spi.init(baudrate=4000_000)
self.dc_pin = Pin(DC_PIN, Pin.OUT)
self.buffer = bytearray(self.height * self.width // 8)
super().__init__(self.buffer, self.width, self.height, framebuf.MONO_HLSB)
self.init()
'''
function :Change the pin state
parameter:
pin : pin
value : state
'''
def digital_write(self, pin, value):
pin.value(value)
'''
function : Read the pin state
parameter:
pin : pin
'''
def digital_read(self, pin):
return pin.value()
'''
function : The time delay function
parameter:
delaytime : ms
'''
def delay_ms(self, delaytime):
utime.sleep(delaytime / 1000.0)
'''
function : Write data to SPI
parameter:
data : data
'''
def spi_writebyte(self, data):
self.spi.write(bytearray(data))
'''
function :Hardware reset
parameter:
'''
def reset(self):
self.digital_write(self.reset_pin, 1)
self.delay_ms(20)
self.digital_write(self.reset_pin, 0)
self.delay_ms(2)
self.digital_write(self.reset_pin, 1)
self.delay_ms(20)
'''
function :send command
parameter:
command : Command register
'''
def send_command(self, command):
self.digital_write(self.dc_pin, 0)
self.digital_write(self.cs_pin, 0)
self.spi_writebyte([command])
self.digital_write(self.cs_pin, 1)
'''
function :send data
parameter:
data : Write data
'''
def send_data(self, data):
self.digital_write(self.dc_pin, 1)
self.digital_write(self.cs_pin, 0)
self.spi_writebyte([data])
self.digital_write(self.cs_pin, 1)
def send_data1(self, buf):
self.digital_write(self.dc_pin, 1)
self.digital_write(self.cs_pin, 0)
self.spi.write(bytearray(buf))
self.digital_write(self.cs_pin, 1)
'''
function :Wait until the busy_pin goes LOW
parameter:
'''
def ReadBusy(self):
print('busy')
self.delay_ms(10)
while(self.digital_read(self.busy_pin) == 1): # 0: idle, 1: busy
self.delay_ms(10)
print('busy release')
'''
function : Turn On Display
parameter:
'''
def TurnOnDisplay(self):
self.send_command(0x22) # Display Update Control
self.send_data(0xf7)
self.send_command(0x20) # Activate Display Update Sequence
self.ReadBusy()
'''
function : Turn On Display Fast
parameter:
'''
def TurnOnDisplay_Fast(self):
self.send_command(0x22) # Display Update Control
self.send_data(0xC7) # fast:0x0c, quality:0x0f, 0xcf
self.send_command(0x20) # Activate Display Update Sequence
self.ReadBusy()
'''
function : Turn On Display Part
parameter:
'''
def TurnOnDisplayPart(self):
self.send_command(0x22) # Display Update Control
self.send_data(0xff) # fast:0x0c, quality:0x0f, 0xcf
self.send_command(0x20) # Activate Display Update Sequence
self.ReadBusy()
'''
function : Setting the display window
parameter:
Xstart : X-axis starting position
Ystart : Y-axis starting position
Xend : End position of X-axis
Yend : End position of Y-axis
'''
def SetWindows(self, Xstart, Ystart, Xend, Yend):
self.send_command(0x44) # SET_RAM_X_ADDRESS_START_END_POSITION
self.send_data((Xstart >> 3) & 0xFF)
self.send_data((Xend >> 3) & 0xFF)
self.send_command(0x45) # SET_RAM_Y_ADDRESS_START_END_POSITION
self.send_data(Ystart & 0xFF)
self.send_data((Ystart >> 8) & 0xFF)
self.send_data(Yend & 0xFF)
self.send_data((Yend >> 8) & 0xFF)
'''
function : Set Cursor
parameter:
Xstart : X-axis starting position
Ystart : Y-axis starting position
'''
def SetCursor(self, Xstart, Ystart):
self.send_command(0x4E) # SET_RAM_X_ADDRESS_COUNTER
self.send_data(Xstart & 0xFF)
self.send_command(0x4F) # SET_RAM_Y_ADDRESS_COUNTER
self.send_data(Ystart & 0xFF)
self.send_data((Ystart >> 8) & 0xFF)
'''
function : Initialize the e-Paper register
parameter:
'''
def init(self):
print('init')
self.reset()
self.delay_ms(100)
self.ReadBusy()
self.send_command(0x12) # SWRESET
self.ReadBusy()
self.send_command(0x01) # Driver output control
self.send_data(0xf9)
self.send_data(0x00)
self.send_data(0x00)
self.send_command(0x11) #data entry mode
self.send_data(0x03)
self.SetWindows(0, 0, self.width-1, self.height-1)
self.SetCursor(0, 0)
self.send_command(0x3C) # BorderWaveform
self.send_data(0x05)
self.send_command(0x21) # Display update control
self.send_data(0x00)
self.send_data(0x80)
self.send_command(0x18) # Read built-in temperature sensor
self.send_data(0x80)
self.ReadBusy()
'''
function : Initialize the e-Paper fast register
parameter:
'''
def init_fast(self):
print('init_fast')
self.reset()
self.delay_ms(100)
self.send_command(0x12) #SWRESET
self.ReadBusy()
self.send_command(0x18) # Read built-in temperature sensor
self.send_command(0x80)
self.send_command(0x11) # data entry mode
self.send_data(0x03)
self.SetWindow(0, 0, self.width-1, self.height-1)
self.SetCursor(0, 0)
self.send_command(0x22) # Load temperature value
self.send_data(0xB1)
self.send_command(0x20)
self.ReadBusy()
self.send_command(0x1A) # Write to temperature register
self.send_data(0x64)
self.send_data(0x00)
self.send_command(0x22) # Load temperature value
self.send_data(0x91)
self.send_command(0x20)
self.ReadBusy()
return 0
'''
function : Clear screen
parameter:
'''
def Clear(self):
self.send_command(0x24)
self.send_data1([0xff] * self.height * int(self.width / 8))
self.TurnOnDisplay()
'''
function : Sends the image buffer in RAM to e-Paper and displays
parameter:
image : Image data
'''
def display(self, image):
self.send_command(0x24)
self.send_data1(image)
self.TurnOnDisplay()
def display_fast(self, image):
self.send_command(0x24)
self.send_data2(image)
self.TurnOnDisplay_Fast()
'''
function : Refresh a base image
parameter:
image : Image data
'''
def Display_Base(self, image):
self.send_command(0x24)
self.send_data1(image)
self.send_command(0x26)
self.send_data1(image)
self.TurnOnDisplay()
'''
function : Sends the image buffer in RAM to e-Paper and partial refresh
parameter:
image : Image data
'''
def displayPartial(self, image):
self.reset()
self.send_command(0x3C) # BorderWavefrom
self.send_data(0x80)
self.send_command(0x01) # Driver output control
self.send_data(0xF9)
self.send_data(0x00)
self.send_data(0x00)
self.send_command(0x11) # data entry mode
self.send_data(0x03)
self.SetWindows(0, 0, self.width-1, self.height-1)
self.SetCursor(0, 0)
self.send_command(0x24) # WRITE_RAM
self.send_data1(image)
self.TurnOnDisplayPart()
'''
function : Enter sleep mode
parameter:
'''
def sleep(self):
self.send_command(0x10) #enter deep sleep
self.send_data(0x01)
self.delay_ms(100)
class EPD_2in13_V4_Landscape(framebuf.FrameBuffer):
def __init__(self):
self.reset_pin = Pin(RST_PIN, Pin.OUT)
self.busy_pin = Pin(BUSY_PIN, Pin.IN, Pin.PULL_UP)
self.cs_pin = Pin(CS_PIN, Pin.OUT)
if EPD_WIDTH % 8 == 0:
self.width = EPD_WIDTH
else :
self.width = (EPD_WIDTH // 8) * 8 + 8
self.height = EPD_HEIGHT
self.spi = SPI(1)
self.spi.init(baudrate=4000_000)
self.dc_pin = Pin(DC_PIN, Pin.OUT)
self.buffer = bytearray(self.height * self.width // 8)
super().__init__(self.buffer, self.height, self.width, framebuf.MONO_VLSB)
self.init()
def digital_write(self, pin, value):
pin.value(value)
def digital_read(self, pin):
return pin.value()
def delay_ms(self, delaytime):
utime.sleep(delaytime / 1000.0)
def spi_writebyte(self, data):
self.spi.write(bytearray(data))
def reset(self):
self.digital_write(self.reset_pin, 1)
self.delay_ms(20)
self.digital_write(self.reset_pin, 0)
self.delay_ms(2)
self.digital_write(self.reset_pin, 1)
self.delay_ms(20)
def send_command(self, command):
self.digital_write(self.dc_pin, 0)
self.digital_write(self.cs_pin, 0)
self.spi_writebyte([command])
self.digital_write(self.cs_pin, 1)
def send_data(self, data):
self.digital_write(self.dc_pin, 1)
self.digital_write(self.cs_pin, 0)
self.spi_writebyte([data])
self.digital_write(self.cs_pin, 1)
def send_data1(self, buf):
self.digital_write(self.dc_pin, 1)
self.digital_write(self.cs_pin, 0)
self.spi.write(bytearray(buf))
self.digital_write(self.cs_pin, 1)
def ReadBusy(self):
print('busy')
self.delay_ms(10)
while(self.digital_read(self.busy_pin) == 1): # 0: idle, 1: busy
self.delay_ms(10)
print('busy release')
'''
function : Turn On Display
parameter:
'''
def TurnOnDisplay(self):
self.send_command(0x22) # Display Update Control
self.send_data(0xf7)
self.send_command(0x20) # Activate Display Update Sequence
self.ReadBusy()
'''
function : Turn On Display Fast
parameter:
'''
def TurnOnDisplay_Fast(self):
self.send_command(0x22) # Display Update Control
self.send_data(0xC7) # fast:0x0c, quality:0x0f, 0xcf
self.send_command(0x20) # Activate Display Update Sequence
self.ReadBusy()
'''
function : Turn On Display Part
parameter:
'''
def TurnOnDisplayPart(self):
self.send_command(0x22) # Display Update Control
self.send_data(0xff) # fast:0x0c, quality:0x0f, 0xcf
self.send_command(0x20) # Activate Display Update Sequence
self.ReadBusy()
'''
function : Setting the display window
parameter:
Xstart : X-axis starting position
Ystart : Y-axis starting position
Xend : End position of X-axis
Yend : End position of Y-axis
'''
def SetWindows(self, Xstart, Ystart, Xend, Yend):
self.send_command(0x44) # SET_RAM_X_ADDRESS_START_END_POSITION
self.send_data((Xstart >> 3) & 0xFF)
self.send_data((Xend >> 3) & 0xFF)
self.send_command(0x45) # SET_RAM_Y_ADDRESS_START_END_POSITION
self.send_data(Ystart & 0xFF)
self.send_data((Ystart >> 8) & 0xFF)
self.send_data(Yend & 0xFF)
self.send_data((Yend >> 8) & 0xFF)
'''
function : Set Cursor
parameter:
Xstart : X-axis starting position
Ystart : Y-axis starting position
'''
def SetCursor(self, Xstart, Ystart):
self.send_command(0x4E) # SET_RAM_X_ADDRESS_COUNTER
self.send_data(Xstart & 0xFF)
self.send_command(0x4F) # SET_RAM_Y_ADDRESS_COUNTER
self.send_data(Ystart & 0xFF)
self.send_data((Ystart >> 8) & 0xFF)
'''
function : Initialize the e-Paper register
parameter:
'''
def init(self):
print('init')
self.reset()
self.delay_ms(100)
self.ReadBusy()
self.send_command(0x12) # SWRESET
self.ReadBusy()
self.send_command(0x01) # Driver output control
self.send_data(0xf9)
self.send_data(0x00)
self.send_data(0x00)
self.send_command(0x11) #data entry mode
self.send_data(0x07)
self.SetWindows(0, 0, self.width-1, self.height-1)
self.SetCursor(0, 0)
self.send_command(0x3C) # BorderWaveform
self.send_data(0x05)
self.send_command(0x21) # Display update control
self.send_data(0x00)
self.send_data(0x80)
self.send_command(0x18) # Read built-in temperature sensor
self.send_data(0x80)
self.ReadBusy()
'''
function : Initialize the e-Paper fast register
parameter:
'''
def init_fast(self):
print('init_fast')
self.reset()
self.delay_ms(100)
self.send_command(0x12) #SWRESET
self.ReadBusy()
self.send_command(0x18) # Read built-in temperature sensor
self.send_command(0x80)
self.send_command(0x11) # data entry mode
self.send_data(0x07)
self.SetWindow(0, 0, self.width-1, self.height-1)
self.SetCursor(0, 0)
self.send_command(0x22) # Load temperature value
self.send_data(0xB1)
self.send_command(0x20)
self.ReadBusy()
self.send_command(0x1A) # Write to temperature register
self.send_data(0x64)
self.send_data(0x00)
self.send_command(0x22) # Load temperature value
self.send_data(0x91)
self.send_command(0x20)
self.ReadBusy()
return 0
'''
function : Clear screen
parameter:
'''
def Clear(self):
self.send_command(0x24)
self.send_data1([0xff] * self.height * int(self.width / 8))
self.TurnOnDisplay()
'''
function : Sends the image buffer in RAM to e-Paper and displays
parameter:
image : Image data
'''
def display(self, image):
self.send_command(0x24)
for j in range(int(self.width / 8) - 1, -1, -1):
for i in range(0, self.height):
self.send_data(image[i + j * self.height])
self.TurnOnDisplay()
def display_fast(self, image):
self.send_command(0x24)
for j in range(int(self.width / 8) - 1, -1, -1):
for i in range(0, self.height):
self.send_data(image[i + j * self.height])
self.TurnOnDisplay_Fast()
'''
function : Refresh a base image
parameter:
image : Image data
'''
def Display_Base(self, image):
self.send_command(0x24)
for j in range(int(self.width / 8) - 1, -1, -1):
for i in range(0, self.height):
self.send_data(image[i + j * self.height])
self.send_command(0x26)
for j in range(int(self.width / 8) - 1, -1, -1):
for i in range(0, self.height):
self.send_data(image[i + j * self.height])
self.TurnOnDisplay()
'''
function : Sends the image buffer in RAM to e-Paper and partial refresh
parameter:
image : Image data
'''
def displayPartial(self, image):
self.reset()
self.send_command(0x3C) # BorderWavefrom
self.send_data(0x80)
self.send_command(0x01) # Driver output control
self.send_data(0xF9)
self.send_data(0x00)
self.send_data(0x00)
self.send_command(0x11) # data entry mode
self.send_data(0x07)
self.SetWindows(0, 0, self.width-1, self.height-1)
self.SetCursor(0, 0)
self.send_command(0x24) # WRITE_RAM
for j in range(int(self.width / 8) - 1, -1, -1):
for i in range(0, self.height):
self.send_data(image[i + j * self.height])
self.TurnOnDisplayPart()
'''
function : Enter sleep mode
parameter:
'''
def sleep(self):
self.send_command(0x10) #enter deep sleep
self.send_data(0x01)
self.delay_ms(100)
if __name__=='__main__':
epd = EPD_2in13_V4_Landscape()
epd.Clear()
epd.fill(0xff)
epd.text("Waveshare", 0, 10, 0x00)
epd.text("ePaper-2.13_V4", 0, 20, 0x00)
epd.text("Raspberry Pico", 0, 30, 0x00)
epd.text("Hello World", 0, 40, 0x00)
epd.display(epd.buffer)
epd.delay_ms(2000)
epd.vline(5, 55, 60, 0x00)
epd.vline(100, 55, 60, 0x00)
epd.hline(5, 55, 95, 0x00)
epd.hline(5, 115, 95, 0x00)
epd.line(5, 55, 100, 115, 0x00)
epd.line(100, 55, 5, 115, 0x00)
epd.display(epd.buffer)
epd.delay_ms(2000)
epd.rect(130, 10, 40, 80, 0x00)
epd.fill_rect(190, 10, 40, 80, 0x00)
epd.Display_Base(epd.buffer)
epd.delay_ms(2000)
epd.init()
for i in range(0, 10):
epd.fill_rect(175, 105, 10, 10, 0xff)
epd.text(str(i), 177, 106, 0x00)
epd.displayPartial(epd.buffer)
print("sleep")
epd.init()
epd.Clear()
epd.delay_ms(2000)
epd.sleep()
epd = EPD_2in13_V4_Portrait()
epd.Clear()
epd.fill(0xff)
epd.text("Waveshare", 0, 10, 0x00)
epd.text("ePaper-2.13_V4", 0, 30, 0x00)
epd.text("Raspberry Pico", 0, 50, 0x00)
epd.text("Hello World", 0, 70, 0x00)
epd.display(epd.buffer)
epd.delay_ms(2000)
epd.vline(10, 90, 60, 0x00)
epd.vline(90, 90, 60, 0x00)
epd.hline(10, 90, 80, 0x00)
epd.hline(10, 150, 80, 0x00)
epd.line(10, 90, 90, 150, 0x00)
epd.line(90, 90, 10, 150, 0x00)
epd.display(epd.buffer)
epd.delay_ms(2000)
epd.rect(10, 180, 50, 40, 0x00)
epd.fill_rect(60, 180, 50, 40, 0x00)
epd.Display_Base(epd.buffer)
epd.delay_ms(2000)
epd.init()
for i in range(0, 10):
epd.fill_rect(40, 230, 40, 10, 0xff)
epd.text(str(i), 60, 230, 0x00)
epd.displayPartial(epd.buffer)
print("sleep")
epd.init()
epd.Clear()
epd.delay_ms(2000)
epd.sleep()まとめ
工夫すればいろいろなものを省電力で表示することができます。
日本語を表示する方法も後日アップしますので、まずはご自身で試してみてはいかがでしょう。
リンク
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