diff options
Diffstat (limited to 'anzeige0/nodemcu_gpio_lcd.py')
| -rw-r--r-- | anzeige0/nodemcu_gpio_lcd.py | 168 |
1 files changed, 168 insertions, 0 deletions
diff --git a/anzeige0/nodemcu_gpio_lcd.py b/anzeige0/nodemcu_gpio_lcd.py new file mode 100644 index 0000000..0bb839c --- /dev/null +++ b/anzeige0/nodemcu_gpio_lcd.py @@ -0,0 +1,168 @@ +"""Implements a HD44780 character LCD connected via NodeMCU GPIO pins.""" + +from lcd_api import LcdApi +from machine import Pin +from utime import sleep_ms, sleep_us + + +class GpioLcd(LcdApi): + """Implements a HD44780 character LCD connected via NodeMCU GPIO pins.""" + + def __init__(self, rs_pin, enable_pin, d0_pin=None, d1_pin=None, + d2_pin=None, d3_pin=None, d4_pin=None, d5_pin=None, + d6_pin=None, d7_pin=None, rw_pin=None, backlight_pin=None, + num_lines=2, num_columns=16): + """Constructs the GpioLcd object. All of the arguments must be Pin + objects which describe which pin the given line from the LCD is + connected to. + + When used in 4-bit mode, only D4, D5, D6, and D7 are physically + connected to the LCD panel. This function allows you call it like + GpioLcd(rs, enable, D4, D5, D6, D7) and it will interpret that as + if you had actually called: + GpioLcd(rs, enable, d4=D4, d5=D5, d6=D6, d7=D7) + + The enable 8-bit mode, you need pass d0 through d7. + + The rw pin isn't used by this library, but if you specify it, then + it will be set low. + """ + self.rs_pin = rs_pin + self.enable_pin = enable_pin + self.rw_pin = rw_pin + self.backlight_pin = backlight_pin + self._4bit = True + if d4_pin and d5_pin and d6_pin and d7_pin: + self.d0_pin = d0_pin + self.d1_pin = d1_pin + self.d2_pin = d2_pin + self.d3_pin = d3_pin + self.d4_pin = d4_pin + self.d5_pin = d5_pin + self.d6_pin = d6_pin + self.d7_pin = d7_pin + if self.d0_pin and self.d1_pin and self.d2_pin and self.d3_pin: + self._4bit = False + else: + # This is really 4-bit mode, and the 4 data pins were just + # passed as the first 4 arguments, so we switch things around. + self.d0_pin = None + self.d1_pin = None + self.d2_pin = None + self.d3_pin = None + self.d4_pin = d0_pin + self.d5_pin = d1_pin + self.d6_pin = d2_pin + self.d7_pin = d3_pin + self.rs_pin.init(Pin.OUT) + self.rs_pin.value(0) + if self.rw_pin: + self.rw_pin.init(Pin.OUT) + self.rw_pin.value(0) + self.enable_pin.init(Pin.OUT) + self.enable_pin.value(0) + self.d4_pin.init(Pin.OUT) + self.d5_pin.init(Pin.OUT) + self.d6_pin.init(Pin.OUT) + self.d7_pin.init(Pin.OUT) + self.d4_pin.value(0) + self.d5_pin.value(0) + self.d6_pin.value(0) + self.d7_pin.value(0) + if not self._4bit: + self.d0_pin.init(Pin.OUT) + self.d1_pin.init(Pin.OUT) + self.d2_pin.init(Pin.OUT) + self.d3_pin.init(Pin.OUT) + self.d0_pin.value(0) + self.d1_pin.value(0) + self.d2_pin.value(0) + self.d3_pin.value(0) + if self.backlight_pin is not None: + self.backlight_pin.init(Pin.OUT) + self.backlight_pin.value(0) + + # See about splitting this into begin + + sleep_ms(20) # Allow LCD time to powerup + # Send reset 3 times + self.hal_write_init_nibble(self.LCD_FUNCTION_RESET) + sleep_ms(5) # need to delay at least 4.1 msec + self.hal_write_init_nibble(self.LCD_FUNCTION_RESET) + sleep_ms(1) + self.hal_write_init_nibble(self.LCD_FUNCTION_RESET) + sleep_ms(1) + cmd = self.LCD_FUNCTION + if not self._4bit: + cmd |= self.LCD_FUNCTION_8BIT + self.hal_write_init_nibble(cmd) + sleep_ms(1) + LcdApi.__init__(self, num_lines, num_columns) + if num_lines > 1: + cmd |= self.LCD_FUNCTION_2LINES + self.hal_write_command(cmd) + + def hal_pulse_enable(self): + """Pulse the enable line high, and then low again.""" + self.enable_pin.value(0) + sleep_us(1) + self.enable_pin.value(1) + sleep_us(1) # Enable pulse needs to be > 450 nsec + self.enable_pin.value(0) + sleep_us(100) # Commands need > 37us to settle + + def hal_write_init_nibble(self, nibble): + """Writes an initialization nibble to the LCD. + + This particular function is only used during initialization. + """ + self.hal_write_4bits(nibble >> 4) + + def hal_backlight_on(self): + """Allows the hal layer to turn the backlight on.""" + if self.backlight_pin: + self.backlight_pin.value(1) + + def hal_backlight_off(self): + """Allows the hal layer to turn the backlight off.""" + if self.backlight_pin: + self.backlight_pin.value(0) + + def hal_write_command(self, cmd): + """Writes a command to the LCD. + + Data is latched on the falling edge of E. + """ + self.rs_pin.value(0) + self.hal_write_8bits(cmd) + if cmd <= 3: + # The home and clear commands require a worst + # case delay of 4.1 msec + sleep_ms(5) + + def hal_write_data(self, data): + """Write data to the LCD.""" + self.rs_pin.value(1) + self.hal_write_8bits(data) + + def hal_write_8bits(self, value): + """Writes 8 bits of data to the LCD.""" + if self.rw_pin: + self.rw_pin.value(0) + if self._4bit: + self.hal_write_4bits(value >> 4) + self.hal_write_4bits(value) + else: + self.d3_pin.value(value & 0x08) + self.d2_pin.value(value & 0x04) + self.d1_pin.value(value & 0x02) + self.d0_pin.value(value & 0x01) + self.hal_write_4bits(value >> 4) + + def hal_write_4bits(self, nibble): + """Writes 4 bits of data to the LCD.""" + self.d7_pin.value(nibble & 0x08) + self.d6_pin.value(nibble & 0x04) + self.d5_pin.value(nibble & 0x02) + self.d4_pin.value(nibble & 0x01) + self.hal_pulse_enable() |