#
# MicroPython LCD1602 ASCII-SCREEN driver, 4-bit interfaces
#

import time
from machine import Pin
from micropython import const

class LCD1602:

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

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

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

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

    # flags for display/cursor shift
#     LCD_DISPLAYMOVE     = const(0x08)
#     LCD_CURSORMOVE      = const(0x00)
#     LCD_MOVERIGHT       = const(0x04)
#     LCD_MOVELEFT        = const(0x00)
# 
#     # flags for function set
#     LCD_8BITMODE        = const(0x10)
#     LCD_4BITMODE        = const(0x00)
#     LCD_2LINE           = const(0x08)
#     LCD_1LINE           = const(0x00)
#     LCD_5x10DOTS        = const(0x04)
#     LCD_5x8DOTS         = const(0x00)

    
    '''
    pins_db = [DB7, DB6, DB5, DB4]
    '''
    def __init__(self, pin_rs, pin_rw, pin_e, pins_db):
        self.pin_rs  = pin_rs
        self.pin_rw  = pin_rw
        self.pin_e   = pin_e
        self.pins_db = pins_db
        
        self.pin_rs.init(Pin.OUT)
        self.pin_rw.init(Pin.OUT)
        self.pin_e.init(Pin.OUT)
        for aPin in self.pins_db:
            aPin.init(Pin.OUT)
#         self.pin_rw.init(self.pin_rw.OUT) # for debug
        self.lcd1602_init()

    def bus_write_4bits(self, aByte, rs_mode=False):
        self.pin_rs.value(rs_mode)
        self.pin_rw.value(False)   # write

        # high-4bit
        time.sleep_us(400) # 400us
        self.pin_e.value(True)
        time.sleep_us(400) # 400us
        for i in range(4):
            if aByte & 0x80:
                self.pins_db[i].value(True)
    #            print(f"pin:{pins_db[i]}, 1") # only for debug
            else:
                self.pins_db[i].value(False)
    #            print(f"pin:{pins_db[i]}, 0") # only for debug

            aByte <<= 1
            
        time.sleep_us(380) # ok!!, tDSW 
        self.pin_e.value(False)
        time.sleep_us(400) # 400us, tH

        # low-4bit
        time.sleep_us(400) # 400us
        self.pin_e.value(True)
        time.sleep_us(400) # 100us
        for i in range(4):
            if aByte & 0x80:
                self.pins_db[i].value(True)
    #            print(f"pin:{pins_db[i]}, 1") # only for debug
            else:
                self.pins_db[i].value(False)
    #            print(f"pin:{pins_db[i]}, 0") # only for debug

            aByte <<= 1
            
        time.sleep_us(400) # tDSW
        self.pin_e.value(False)
        time.sleep_us(400) # 100us, tH
    #    print("") # only for debug

    def bus_send_cmd(self, aByte):
        self.bus_write_4bits(aByte)

    def bus_send_data(self, aByte):
        self.bus_write_4bits(aByte, True)

    def lcd1602_init(self):
        self.bus_send_cmd(0x33)  # set 8bit mode, twice
        self.bus_send_cmd(0x32)  # set 8bit mode, then 4bit mode

        self.bus_send_cmd(0x28)  # set 4bit mode, 2-line, 5x7 mode

        self.bus_send_cmd(0x0f)	# Display On, Cursor On, Cursor Blink
        self.bus_send_cmd(0x01)	# Display Clear
        self.bus_send_cmd(0x06)	# Entry Mode, cursor moves to next
        self.bus_send_cmd(0x80)	# Initialize DDRAM address to zero

    def message(self, text):
        """ Send string to LCD. Newline wraps to second line"""
        self.bus_send_cmd(0x80) # next line
        for char in text:
            if char == '\n':
                self.bus_send_cmd(0xc0) # next line
            else:
                self.bus_send_data(ord(char))

    def clear_display(self):
        self.bus_send_cmd(self.LCD_CLEARDISPLAY)
#         time.sleep_ms(100)


# ---- main ----
if __name__ == "__main__":
    obj_1602 = LCD1602(pin_rs=Pin(13), pin_rw=Pin(12), pin_e=Pin(14), pins_db=[Pin(5), Pin(18), Pin(19), Pin(21)])
    # obj_1602 = LCD1602(pin_rs=Pin(32), pin_rw=Pin(33), pin_e=Pin(17), pins_db=[Pin(12), Pin(14), Pin(27), Pin(16)])
    obj_1602.message("Hello,\nZhang!")
    
    time.sleep_ms(5000)
    obj_1602.clear_display()
    obj_1602.message("2nd message here.")