From 74973624deed05d1cc8b297fb1d877cadad50969 Mon Sep 17 00:00:00 2001 From: Yves Fischer Date: Thu, 2 Aug 2018 17:21:14 +0200 Subject: new commit-history root - cleaned off passwords --- anzeige0/lcd_api.py | 195 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 195 insertions(+) create mode 100644 anzeige0/lcd_api.py (limited to 'anzeige0/lcd_api.py') diff --git a/anzeige0/lcd_api.py b/anzeige0/lcd_api.py new file mode 100644 index 0000000..38b60da --- /dev/null +++ b/anzeige0/lcd_api.py @@ -0,0 +1,195 @@ +"""Provides an API for talking to HD44780 compatible character LCDs.""" + +import time + +class LcdApi: + """Implements the API for talking with HD44780 compatible character LCDs. + This class only knows what commands to send to the LCD, and not how to get + them to the LCD. + + It is expected that a derived class will implement the hal_xxx functions. + """ + + # The following constant names were lifted from the avrlib lcd.h + # header file, however, I changed the definitions from bit numbers + # to bit masks. + # + # HD44780 LCD controller command set + + LCD_CLR = 0x01 # DB0: clear display + LCD_HOME = 0x02 # DB1: return to home position + + LCD_ENTRY_MODE = 0x04 # DB2: set entry mode + LCD_ENTRY_INC = 0x02 # --DB1: increment + LCD_ENTRY_SHIFT = 0x01 # --DB0: shift + + LCD_ON_CTRL = 0x08 # DB3: turn lcd/cursor on + LCD_ON_DISPLAY = 0x04 # --DB2: turn display on + LCD_ON_CURSOR = 0x02 # --DB1: turn cursor on + LCD_ON_BLINK = 0x01 # --DB0: blinking cursor + + LCD_MOVE = 0x10 # DB4: move cursor/display + LCD_MOVE_DISP = 0x08 # --DB3: move display (0-> move cursor) + LCD_MOVE_RIGHT = 0x04 # --DB2: move right (0-> left) + + LCD_FUNCTION = 0x20 # DB5: function set + LCD_FUNCTION_8BIT = 0x10 # --DB4: set 8BIT mode (0->4BIT mode) + LCD_FUNCTION_2LINES = 0x08 # --DB3: two lines (0->one line) + LCD_FUNCTION_10DOTS = 0x04 # --DB2: 5x10 font (0->5x7 font) + LCD_FUNCTION_RESET = 0x30 # See "Initializing by Instruction" section + + LCD_CGRAM = 0x40 # DB6: set CG RAM address + LCD_DDRAM = 0x80 # DB7: set DD RAM address + + LCD_RS_CMD = 0 + LCD_RS_DATA = 1 + + LCD_RW_WRITE = 0 + LCD_RW_READ = 1 + + def __init__(self, num_lines, num_columns): + self.num_lines = num_lines + if self.num_lines > 4: + self.num_lines = 4 + self.num_columns = num_columns + if self.num_columns > 40: + self.num_columns = 40 + self.cursor_x = 0 + self.cursor_y = 0 + self.backlight = True + self.display_off() + self.backlight_on() + self.clear() + self.hal_write_command(self.LCD_ENTRY_MODE | self.LCD_ENTRY_INC) + self.hide_cursor() + self.display_on() + + def clear(self): + """Clears the LCD display and moves the cursor to the top left + corner. + """ + self.hal_write_command(self.LCD_CLR) + self.hal_write_command(self.LCD_HOME) + self.cursor_x = 0 + self.cursor_y = 0 + + def show_cursor(self): + """Causes the cursor to be made visible.""" + self.hal_write_command(self.LCD_ON_CTRL | self.LCD_ON_DISPLAY | + self.LCD_ON_CURSOR) + + def hide_cursor(self): + """Causes the cursor to be hidden.""" + self.hal_write_command(self.LCD_ON_CTRL | self.LCD_ON_DISPLAY) + + def blink_cursor_on(self): + """Turns on the cursor, and makes it blink.""" + self.hal_write_command(self.LCD_ON_CTRL | self.LCD_ON_DISPLAY | + self.LCD_ON_CURSOR | self.LCD_ON_BLINK) + + def blink_cursor_off(self): + """Turns on the cursor, and makes it no blink (i.e. be solid).""" + self.hal_write_command(self.LCD_ON_CTRL | self.LCD_ON_DISPLAY | + self.LCD_ON_CURSOR) + + def display_on(self): + """Turns on (i.e. unblanks) the LCD.""" + self.hal_write_command(self.LCD_ON_CTRL | self.LCD_ON_DISPLAY) + + def display_off(self): + """Turns off (i.e. blanks) the LCD.""" + self.hal_write_command(self.LCD_ON_CTRL) + + def backlight_on(self): + """Turns the backlight on. + + This isn't really an LCD command, but some modules have backlight + controls, so this allows the hal to pass through the command. + """ + self.backlight = True + self.hal_backlight_on() + + def backlight_off(self): + """Turns the backlight off. + + This isn't really an LCD command, but some modules have backlight + controls, so this allows the hal to pass through the command. + """ + self.backlight = False + self.hal_backlight_off() + + def move_to(self, cursor_x, cursor_y): + """Moves the cursor position to the indicated position. The cursor + position is zero based (i.e. cursor_x == 0 indicates first column). + """ + self.cursor_x = cursor_x + self.cursor_y = cursor_y + addr = cursor_x & 0x3f + if cursor_y & 1: + addr += 0x40 # Lines 1 & 3 add 0x40 + if cursor_y & 2: + addr += 0x14 # Lines 2 & 3 add 0x14 + self.hal_write_command(self.LCD_DDRAM | addr) + + def putchar(self, char): + """Writes the indicated character to the LCD at the current cursor + position, and advances the cursor by one position. + """ + if char != '\n': + self.hal_write_data(ord(char)) + self.cursor_x += 1 + if self.cursor_x >= self.num_columns or char == '\n': + self.cursor_x = 0 + self.cursor_y += 1 + if self.cursor_y >= self.num_lines: + self.cursor_y = 0 + self.move_to(self.cursor_x, self.cursor_y) + + def putstr(self, string): + """Write the indicated string to the LCD at the current cursor + position and advances the cursor position appropriately. + """ + for char in string: + self.putchar(char) + + def custom_char(self, location, charmap): + """Write a character to one of the 8 CGRAM locations, available + as chr(0) through chr(7). + """ + location &= 0x7 + self.hal_write_command(self.LCD_CGRAM | (location << 3)) + time.sleep_us(40) + for i in range(8): + self.hal_write_data(charmap[i]) + time.sleep_us(40) + self.move_to(self.cursor_x, self.cursor_y) + + def hal_backlight_on(self): + """Allows the hal layer to turn the backlight on. + + If desired, a derived HAL class will implement this function. + """ + pass + + def hal_backlight_off(self): + """Allows the hal layer to turn the backlight off. + + If desired, a derived HAL class will implement this function. + """ + pass + + def hal_write_command(self, cmd): + """Write a command to the LCD. + + It is expected that a derived HAL class will implement this + function. + """ + raise NotImplementedError + + def hal_write_data(self, data): + """Write data to the LCD. + + It is expected that a derived HAL class will implement this + function. + """ + raise NotImplementedError -- cgit v1.2.1