Get study queue information from WaniKani API and display on 20x4 LCD screen

wanikani_lcd.md

Parts used

• Raspberry Pi (Model B)
• 20x4 LCD screen (like this one)
• 10K Potentiometer (like this one)
• Breadboard
• Breadboard Wires
• Breakout header pins (0.1-inch)

Hardware wiring instructions

The instructions I used for wiring were taken from this Adafruit tutorial. I don't have the Adafruit Pi Cobbler kit that they used in that tutorial, so to figure out which GPIO pin numbers I needed, I used this guide.

Software

You need to install a few libraries to get Python set up to use the script below. The following will install some additional Python development libraries and additional Python modules.

sudo apt-get install python-dev python-setuptools
sudo easy_install -U distribute
sudo apt-get install python-pip
sudo pip install rpi.gpio

Once you have these set up, you can save the script below (mostly taken from Adafruit's Raspberry Pi Python repository) to wanikani_lcd.py, change the WaniKani API Key where indicated towards the end of the script, and execute it:

sudo ./wanikani_lcd.py

This script must be run as root to allow Python to use the GPIO pins.

Periodically updating status

I created a cron job as root to update my stats every five minutes (you can change to update at whatever frequency you choose). Log in as root and open the root user's crontab:

sudo su -
crontab -e

Then add the following line (assuming you saved the Python script in the /home/pi directory):

*/5 * * * * /home/pi/wanikani_lcd.py

All wired up and working

(Apologies for the messy wiring - I promise to clean this up and maybe put it in a more permanent home)

wanikani_lcd.py

#!/usr/bin/python

#
# based on code from lrvick and LiquidCrystal
# lrvic - https://github.com/lrvick/raspi-hd44780/blob/master/hd44780.py
# LiquidCrystal - https://github.com/arduino/Arduino/blob/master/libraries/LiquidCrystal/LiquidCrystal.cpp
# Adafruit Raspberry Pi Python Code for LCD - https://github.com/adafruit/Adafruit-Raspberry-Pi-Python-Code/blob/master/Adafruit_CharLCD/Adafruit_CharLCD.py
#

from time import sleep

class Adafruit_CharLCD:

    # commands
    LCD_CLEARDISPLAY            = 0x01
    LCD_RETURNHOME              = 0x02
    LCD_ENTRYMODESET            = 0x04
    LCD_DISPLAYCONTROL          = 0x08
    LCD_CURSORSHIFT             = 0x10
    LCD_FUNCTIONSET             = 0x20
    LCD_SETCGRAMADDR            = 0x40
    LCD_SETDDRAMADDR            = 0x80

    # flags for display entry mode
    LCD_ENTRYRIGHT              = 0x00
    LCD_ENTRYLEFT               = 0x02
    LCD_ENTRYSHIFTINCREMENT     = 0x01
    LCD_ENTRYSHIFTDECREMENT     = 0x00

    # flags for display on/off control
    LCD_DISPLAYON               = 0x04
    LCD_DISPLAYOFF              = 0x00
    LCD_CURSORON                = 0x02
    LCD_CURSOROFF               = 0x00
    LCD_BLINKON                 = 0x01
    LCD_BLINKOFF                = 0x00

    # flags for display/cursor shift
    LCD_DISPLAYMOVE             = 0x08
    LCD_CURSORMOVE              = 0x00

    # flags for display/cursor shift
    LCD_DISPLAYMOVE             = 0x08
    LCD_CURSORMOVE              = 0x00
    LCD_MOVERIGHT               = 0x04
    LCD_MOVELEFT                = 0x00

    # flags for function set
    LCD_8BITMODE                = 0x10
    LCD_4BITMODE                = 0x00
    LCD_2LINE                   = 0x08
    LCD_1LINE                   = 0x00
    LCD_5x10DOTS                = 0x04
    LCD_5x8DOTS                 = 0x00



    def __init__(self, pin_rs=25, pin_e=24, pins_db=[23, 17, 27, 22], GPIO = None):
        # Emulate the old behavior of using RPi.GPIO if we haven't been given
        # an explicit GPIO interface to use
        if not GPIO:
            import RPi.GPIO as GPIO
        self.GPIO = GPIO
        self.pin_rs = pin_rs
        self.pin_e = pin_e
        self.pins_db = pins_db

        self.GPIO.setwarnings(False)
        self.GPIO.setmode(GPIO.BCM)
        self.GPIO.setup(self.pin_e, GPIO.OUT)
        self.GPIO.setup(self.pin_rs, GPIO.OUT)

        for pin in self.pins_db:
            self.GPIO.setup(pin, GPIO.OUT)

        self.write4bits(0x33) # initialization
        self.write4bits(0x32) # initialization
        self.write4bits(0x28) # 2 line 5x7 matrix
        self.write4bits(0x0C) # turn cursor off 0x0E to enable cursor
        self.write4bits(0x06) # shift cursor right

        self.displaycontrol = self.LCD_DISPLAYON | self.LCD_CURSOROFF | self.LCD_BLINKOFF

        self.displayfunction = self.LCD_4BITMODE | self.LCD_1LINE | self.LCD_5x8DOTS
        self.displayfunction |= self.LCD_2LINE

        """ Initialize to default text direction (for romance languages) """
        self.displaymode =  self.LCD_ENTRYLEFT | self.LCD_ENTRYSHIFTDECREMENT
        self.write4bits(self.LCD_ENTRYMODESET | self.displaymode) #  set the entry mode

        self.clear()


    def begin(self, cols, lines):

        if (lines > 1):
                self.numlines = lines
                self.displayfunction |= self.LCD_2LINE
                self.currline = 0


    def home(self):
        self.write4bits(self.LCD_RETURNHOME) # set cursor position to zero
        self.delayMicroseconds(3000) # this command takes a long time!


    def clear(self):

        self.write4bits(self.LCD_CLEARDISPLAY) # command to clear display
        self.delayMicroseconds(3000)    # 3000 microsecond sleep, clearing the display takes a long time


    def setCursor(self, col, row):

        self.row_offsets = [ 0x00, 0x40, 0x14, 0x54 ]

        if ( row > self.numlines ):
                row = self.numlines - 1 # we count rows starting w/0

        self.write4bits(self.LCD_SETDDRAMADDR | (col + self.row_offsets[row]))


    def noDisplay(self):
        """ Turn the display off (quickly) """

        self.displaycontrol &= ~self.LCD_DISPLAYON
        self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)


    def display(self):
        """ Turn the display on (quickly) """

        self.displaycontrol |= self.LCD_DISPLAYON
        self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)

    def noCursor(self):
        """ Turns the underline cursor on/off """

        self.displaycontrol &= ~self.LCD_CURSORON
        self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)


    def cursor(self):
        """ Cursor On """

        self.displaycontrol |= self.LCD_CURSORON
        self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)


    def noBlink(self):
        """ Turn on and off the blinking cursor """

        self.displaycontrol &= ~self.LCD_BLINKON
        self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)


    def noBlink(self):
        """ Turn on and off the blinking cursor """

        self.displaycontrol &= ~self.LCD_BLINKON
        self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)


    def DisplayLeft(self):
        """ These commands scroll the display without changing the RAM """

        self.write4bits(self.LCD_CURSORSHIFT | self.LCD_DISPLAYMOVE | self.LCD_MOVELEFT)

    def scrollDisplayRight(self):
        """ These commands scroll the display without changing the RAM """

        self.write4bits(self.LCD_CURSORSHIFT | self.LCD_DISPLAYMOVE | self.LCD_MOVERIGHT);


    def leftToRight(self):
        """ This is for text that flows Left to Right """

        self.displaymode |= self.LCD_ENTRYLEFT
        self.write4bits(self.LCD_ENTRYMODESET | self.displaymode);


    def rightToLeft(self):
        """ This is for text that flows Right to Left """
        self.displaymode &= ~self.LCD_ENTRYLEFT
        self.write4bits(self.LCD_ENTRYMODESET | self.displaymode)


    def autoscroll(self):
        """ This will 'right justify' text from the cursor """

        self.displaymode |= self.LCD_ENTRYSHIFTINCREMENT
        self.write4bits(self.LCD_ENTRYMODESET | self.displaymode)


    def noAutoscroll(self):
        """ This will 'left justify' text from the cursor """

        self.displaymode &= ~self.LCD_ENTRYSHIFTINCREMENT
        self.write4bits(self.LCD_ENTRYMODESET | self.displaymode)


    def write4bits(self, bits, char_mode=False):
      """ Send command to LCD """

        self.delayMicroseconds(1000) # 1000 microsecond sleep

        bits=bin(bits)[2:].zfill(8)

        self.GPIO.output(self.pin_rs, char_mode)

        for pin in self.pins_db:
            self.GPIO.output(pin, False)

        for i in range(4):
            if bits[i] == "1":
                self.GPIO.output(self.pins_db[::-1][i], True)

        self.pulseEnable()

        for pin in self.pins_db:
            self.GPIO.output(pin, False)

        for i in range(4,8):
            if bits[i] == "1":
                self.GPIO.output(self.pins_db[::-1][i-4], True)

        self.pulseEnable()


    def delayMicroseconds(self, microseconds):
        seconds = microseconds / float(1000000) # divide microseconds by 1 million for seconds
        sleep(seconds)


    def pulseEnable(self):
        self.GPIO.output(self.pin_e, False)
        elf.delayMicroseconds(1)               # 1 microsecond pause - enable pulse must be > 450ns
        self.GPIO.output(self.pin_e, True)
        self.delayMicroseconds(1)               # 1 microsecond pause - enable pulse must be > 450ns
        self.GPIO.output(self.pin_e, False)
        self.delayMicroseconds(1)               # commands need > 37us to settle


    def message(self, text):
        """ Send string to LCD. Newline wraps to second line"""

        for char in text:
            self.write4bits(ord(char),True)


if __name__ == '__main__':
    import urllib
    import json

    # Fetch latest study queue info from Wanikani.
    # Make sure to replace <WANIKANI_API_KEY> with your own API key!
    url = "http://www.wanikani.com/api/user/<WANIKANI_API_KEY>/study-queue"
    data = urllib.urlopen(url).read()
    data = json.loads(data)

    lcd = Adafruit_CharLCD()
    lcd.clear()
    lcd.message("WaniKani Status:")
    lcd.write4bits(0xC0) # Second line of LCD Screen
    lcd.message("Level " + str(data['user_information']['level']))
    lcd.write4bits(0x94) # Third line of LCD Screen
    lcd.message("Lessons: " + str(data['requested_information']['lessons_available']))
    lcd.write4bits(0xD4) # Fourth line of LCD Screen
    lcd.message("Reviews: " + str(data['requested_information']['reviews_available']))

This is too cool. Thanks for sharing!

Super!