291 lines
11 KiB
Python
291 lines
11 KiB
Python
# https://github.com/T-622/RPI-PICO-I2C-LCD
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# Original driver by Tyler Peppy, modified by Benjamin Burkhardt (2024)
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"""
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MIT License
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Copyright (c) 2023 Tyler Peppy
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Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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"""
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import time
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from machine import I2C
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import utime
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import gc
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# PCF8574 pin definitions
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MASK_RS = 0x01 # P0
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MASK_RW = 0x02 # P1
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MASK_E = 0x04 # P2
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SHIFT_BACKLIGHT = 3 # P3
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SHIFT_DATA = 4 # P4-P7
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class LCD_API:
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# Implements the API for talking with HD44780 compatible character LCDs.
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# This class only knows what commands to send to the LCD, and not how to get
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# them to the LCD.
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#
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# It is expected that a derived class will implement the hal_xxx functions.
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#
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# The following constant names were lifted from the avrlib lcd.h header file,
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# with bit numbers changed to bit masks.
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# HD44780 LCD controller command set
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LCD_CLR = 0x01 # DB0: clear display
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LCD_HOME = 0x02 # DB1: return to home position
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LCD_ENTRY_MODE = 0x04 # DB2: set entry mode
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LCD_ENTRY_INC = 0x02 # DB1: increment
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LCD_ENTRY_SHIFT = 0x01 # DB0: shift
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LCD_ON_CTRL = 0x08 # DB3: turn lcd/cursor on
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LCD_ON_DISPLAY = 0x04 # DB2: turn display on
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LCD_ON_CURSOR = 0x02 # DB1: turn cursor on
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LCD_ON_BLINK = 0x01 # DB0: blinking cursor
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LCD_MOVE = 0x10 # DB4: move cursor/display
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LCD_MOVE_DISP = 0x08 # DB3: move display (0-> move cursor)
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LCD_MOVE_RIGHT = 0x04 # DB2: move right (0-> left)
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LCD_FUNCTION = 0x20 # DB5: function set
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LCD_FUNCTION_8BIT = 0x10 # DB4: set 8BIT mode (0->4BIT mode)
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LCD_FUNCTION_2LINES = 0x08 # DB3: two lines (0->one line)
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LCD_FUNCTION_10DOTS = 0x04 # DB2: 5x10 font (0->5x7 font)
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LCD_FUNCTION_RESET = 0x30 # See "Initializing by Instruction" section
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LCD_CGRAM = 0x40 # DB6: set CG RAM address
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LCD_DDRAM = 0x80 # DB7: set DD RAM address
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LCD_RS_CMD = 0
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LCD_RS_DATA = 1
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LCD_RW_WRITE = 0
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LCD_RW_READ = 1
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def __init__(self, num_lines, num_columns):
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self.num_lines = num_lines
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if self.num_lines > 4:
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self.num_lines = 4
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self.num_columns = num_columns
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if self.num_columns > 40:
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self.num_columns = 40
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self.cursor_x = 0
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self.cursor_y = 0
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self.implied_newline = False
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self.backlight = True
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self.display_off()
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self.backlight_on()
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self.clear()
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self.hal_write_command(self.LCD_ENTRY_MODE | self.LCD_ENTRY_INC)
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self.hide_cursor()
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self.display_on()
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def clear(self):
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# Clears the LCD display and moves the cursor to the top left corner
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self.hal_write_command(self.LCD_CLR)
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self.hal_write_command(self.LCD_HOME)
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self.cursor_x = 0
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self.cursor_y = 0
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def show_cursor(self):
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# Causes the cursor to be made visible
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self.hal_write_command(self.LCD_ON_CTRL | self.LCD_ON_DISPLAY |
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self.LCD_ON_CURSOR)
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def hide_cursor(self):
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# Causes the cursor to be hidden
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self.hal_write_command(self.LCD_ON_CTRL | self.LCD_ON_DISPLAY)
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def blink_cursor_on(self):
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# Turns on the cursor, and makes it blink
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self.hal_write_command(self.LCD_ON_CTRL | self.LCD_ON_DISPLAY |
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self.LCD_ON_CURSOR | self.LCD_ON_BLINK)
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def blink_cursor_off(self):
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# Turns on the cursor, and makes it no blink (i.e. be solid)
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self.hal_write_command(self.LCD_ON_CTRL | self.LCD_ON_DISPLAY |
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self.LCD_ON_CURSOR)
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def display_on(self):
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# Turns on (i.e. unblanks) the LCD
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self.hal_write_command(self.LCD_ON_CTRL | self.LCD_ON_DISPLAY)
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def display_off(self):
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# Turns off (i.e. blanks) the LCD
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self.hal_write_command(self.LCD_ON_CTRL)
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def backlight_on(self):
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# Turns the backlight on.
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# This isn't really an LCD command, but some modules have backlight
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# controls, so this allows the hal to pass through the command.
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self.backlight = True
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self.hal_backlight_on()
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def backlight_off(self):
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# Turns the backlight off.
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# This isn't really an LCD command, but some modules have backlight
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# controls, so this allows the hal to pass through the command.
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self.backlight = False
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self.hal_backlight_off()
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def move_to(self, cursor_x, cursor_y):
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# Moves the cursor position to the indicated position. The cursor
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# position is zero based (i.e. cursor_x == 0 indicates first column).
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self.cursor_x = cursor_x
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self.cursor_y = cursor_y
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addr = cursor_x & 0x3f
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if cursor_y & 1:
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addr += 0x40 # Lines 1 & 3 add 0x40
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if cursor_y & 2: # Lines 2 & 3 add number of columns
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addr += self.num_columns
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self.hal_write_command(self.LCD_DDRAM | addr)
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def putchar(self, char):
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# Writes the indicated character to the LCD at the current cursor
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# position, and advances the cursor by one position.
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if char == '\n':
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if self.implied_newline:
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# self.implied_newline means we advanced due to a wraparound,
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# so if we get a newline right after that we ignore it.
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pass
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else:
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self.cursor_x = self.num_columns
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else:
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self.hal_write_data(ord(char))
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self.cursor_x += 1
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if self.cursor_x >= self.num_columns:
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self.cursor_x = 0
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self.cursor_y += 1
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self.implied_newline = (char != '\n')
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if self.cursor_y >= self.num_lines:
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self.cursor_y = 0
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self.move_to(self.cursor_x, self.cursor_y)
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def putstr(self, string):
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# Write the indicated string to the LCD at the current cursor
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# position and advances the cursor position appropriately.
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for char in string:
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self.putchar(char)
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def custom_char(self, location, charmap):
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# Write a character to one of the 8 CGRAM locations, available
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# as chr(0) through chr(7).
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location &= 0x7
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self.hal_write_command(self.LCD_CGRAM | (location << 3))
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self.hal_sleep_us(40)
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for i in range(8):
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self.hal_write_data(charmap[i])
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self.hal_sleep_us(40)
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self.move_to(self.cursor_x, self.cursor_y)
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def hal_backlight_on(self):
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# Allows the hal layer to turn the backlight on.
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# If desired, a derived HAL class will implement this function.
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pass
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def hal_backlight_off(self):
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# Allows the hal layer to turn the backlight off.
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# If desired, a derived HAL class will implement this function.
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pass
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def hal_write_command(self, cmd):
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# Write a command to the LCD.
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# It is expected that a derived HAL class will implement this function.
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raise NotImplementedError
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def hal_write_data(self, data):
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# Write data to the LCD.
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# It is expected that a derived HAL class will implement this function.
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raise NotImplementedError
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def hal_sleep_us(self, usecs):
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# Sleep for some time (given in microseconds)
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time.sleep_us(usecs)
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class I2C_LCD(LCD_API):
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#Implements a HD44780 character LCD connected via PCF8574 on I2C
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def __init__(self, i2c, i2c_addr, num_lines, num_columns):
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self.i2c = i2c
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self.i2c_addr = i2c_addr
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self.i2c.writeto(self.i2c_addr, bytes([0]))
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utime.sleep_ms(20) # Allow LCD time to powerup
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# Send reset 3 times
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self.hal_write_init_nibble(self.LCD_FUNCTION_RESET)
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utime.sleep_ms(5) # Need to delay at least 4.1 msec
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self.hal_write_init_nibble(self.LCD_FUNCTION_RESET)
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utime.sleep_ms(1)
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self.hal_write_init_nibble(self.LCD_FUNCTION_RESET)
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utime.sleep_ms(1)
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# Put LCD into 4-bit mode
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self.hal_write_init_nibble(self.LCD_FUNCTION)
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utime.sleep_ms(1)
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LCD_API.__init__(self, num_lines, num_columns)
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cmd = self.LCD_FUNCTION
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if num_lines > 1:
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cmd |= self.LCD_FUNCTION_2LINES
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self.hal_write_command(cmd)
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gc.collect()
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def hal_write_init_nibble(self, nibble):
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# Writes an initialization nibble to the LCD.
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# This particular function is only used during initialization.
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byte = ((nibble >> 4) & 0x0f) << SHIFT_DATA
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self.i2c.writeto(self.i2c_addr, bytes([byte | MASK_E]))
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self.i2c.writeto(self.i2c_addr, bytes([byte]))
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gc.collect()
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def hal_backlight_on(self):
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# Allows the hal layer to turn the backlight on
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self.i2c.writeto(self.i2c_addr, bytes([1 << SHIFT_BACKLIGHT]))
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gc.collect()
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def hal_backlight_off(self):
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#Allows the hal layer to turn the backlight off
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self.i2c.writeto(self.i2c_addr, bytes([0]))
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gc.collect()
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def hal_write_command(self, cmd):
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# Write a command to the LCD. Data is latched on the falling edge of E.
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byte = ((self.backlight << SHIFT_BACKLIGHT) |
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(((cmd >> 4) & 0x0f) << SHIFT_DATA))
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self.i2c.writeto(self.i2c_addr, bytes([byte | MASK_E]))
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self.i2c.writeto(self.i2c_addr, bytes([byte]))
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byte = ((self.backlight << SHIFT_BACKLIGHT) |
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((cmd & 0x0f) << SHIFT_DATA))
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self.i2c.writeto(self.i2c_addr, bytes([byte | MASK_E]))
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self.i2c.writeto(self.i2c_addr, bytes([byte]))
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if cmd <= 3:
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# The home and clear commands require a worst case delay of 4.1 msec
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utime.sleep_ms(5)
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gc.collect()
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def hal_write_data(self, data):
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# Write data to the LCD. Data is latched on the falling edge of E.
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byte = (MASK_RS |
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(self.backlight << SHIFT_BACKLIGHT) |
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(((data >> 4) & 0x0f) << SHIFT_DATA))
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self.i2c.writeto(self.i2c_addr, bytes([byte | MASK_E]))
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self.i2c.writeto(self.i2c_addr, bytes([byte]))
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byte = (MASK_RS |
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(self.backlight << SHIFT_BACKLIGHT) |
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((data & 0x0f) << SHIFT_DATA))
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self.i2c.writeto(self.i2c_addr, bytes([byte | MASK_E]))
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self.i2c.writeto(self.i2c_addr, bytes([byte]))
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gc.collect()
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