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davehylandsdavehylands
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Merge pull request dhylands#40 from davidwilby/onion_omega
add onion omega interface and test code
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‎lcd/onion_lcd_gpio.py‎

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"""Implements a HD44780 character LCD connected via Onion Omega GPIO pins."""
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from lcd_api import LcdApi
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from time import sleep
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# https://docs.onion.io/omega2-docs/gpio-python-module.html#gpio-python-module
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# requires a python3 modification of the current standard onionGpio (as of 2021-11-20)
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from onionGpio import OnionGpio
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class GpioLcd(LcdApi):
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"""Implements a HD44780 character LCD connected via ESP32 GPIO pins."""
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def __init__(self, rs_pin, enable_pin, d0_pin=None, d1_pin=None,
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d2_pin=None, d3_pin=None, d4_pin=None, d5_pin=None,
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d6_pin=None, d7_pin=None, rw_pin=None, backlight_pin=None,
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num_lines=2, num_columns=16):
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"""Constructs the GpioLcd object. All of the arguments must be onionGpio.OnionGpio
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objects which describe which pin the given line from the LCD is
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connected to.
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When used in 4-bit mode, only D4, D5, D6, and D7 are physically
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connected to the LCD panel. This function allows you call it like
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GpioLcd(rs, enable, D4, D5, D6, D7) and it will interpret that as
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if you had actually called:
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GpioLcd(rs, enable, d4=D4, d5=D5, d6=D6, d7=D7)
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The enable 8-bit mode, you need pass d0 through d7.
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The rw pin isn't used by this library, but if you specify it, then
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it will be set low.
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"""
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self.rs_pin = rs_pin
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self.enable_pin = enable_pin
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self.rw_pin = rw_pin
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self.backlight_pin = backlight_pin
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self._4bit = True
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if d4_pin and d5_pin and d6_pin and d7_pin:
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self.d0_pin = d0_pin
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self.d1_pin = d1_pin
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self.d2_pin = d2_pin
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self.d3_pin = d3_pin
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self.d4_pin = d4_pin
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self.d5_pin = d5_pin
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self.d6_pin = d6_pin
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self.d7_pin = d7_pin
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if self.d0_pin and self.d1_pin and self.d2_pin and self.d3_pin:
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self._4bit = False
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else:
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# This is really 4-bit mode, and the 4 data pins were just
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# passed as the first 4 arguments, so we switch things around.
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self.d0_pin = None
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self.d1_pin = None
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self.d2_pin = None
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self.d3_pin = None
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self.d4_pin = d0_pin
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self.d5_pin = d1_pin
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self.d6_pin = d2_pin
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self.d7_pin = d3_pin
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self.rs_pin.setOutputDirection(0)
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if self.rw_pin:
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self.rw_pin.setOutputDirection(0)
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self.enable_pin.setOutputDirection(0)
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self.d4_pin.setOutputDirection(0)
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self.d5_pin.setOutputDirection(0)
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self.d6_pin.setOutputDirection(0)
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self.d7_pin.setOutputDirection(0)
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if not self._4bit:
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self.d0_pin.setOutputDirection(0)
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self.d1_pin.setOutputDirection(0)
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self.d2_pin.setOutputDirection(0)
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self.d3_pin.setOutputDirection(0)
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if self.backlight_pin is not None:
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self.backlight_pin.setOutputDirection(0)
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# See about splitting this into begin
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sleep(0.020) # 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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sleep(0.005) # 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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sleep(0.001)
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self.hal_write_init_nibble(self.LCD_FUNCTION_RESET)
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sleep(0.001)
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cmd = self.LCD_FUNCTION
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if not self._4bit:
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cmd |= self.LCD_FUNCTION_8BIT
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self.hal_write_init_nibble(cmd)
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sleep(0.001)
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LcdApi.__init__(self, num_lines, num_columns)
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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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def hal_pulse_enable(self):
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"""Pulse the enable line high, and then low again."""
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self.enable_pin.setValue(0)
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sleep(1/1E6)
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self.enable_pin.setValue(1)
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sleep(1/1E6) # Enable pulse needs to be > 450 nsec
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self.enable_pin.setValue(0)
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sleep(100/1E6) # Commands need > 37us to settle
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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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"""
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self.hal_write_4bits(nibble >> 4)
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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 self.backlight_pin:
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self.backlight_pin.setValue(1)
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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 self.backlight_pin:
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self.backlight_pin.setValue(0)
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def hal_write_command(self, cmd):
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"""Writes a command to the LCD.
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Data is latched on the falling edge of E.
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"""
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self.rs_pin.setValue(0)
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self.hal_write_8bits(cmd)
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if cmd <= 3:
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# The home and clear commands require a worst
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# case delay of 4.1 msec
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sleep(0.005)
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def hal_write_data(self, data):
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"""Write data to the LCD."""
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self.rs_pin.setValue(1)
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self.hal_write_8bits(data)
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def hal_write_8bits(self, value):
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"""Writes 8 bits of data to the LCD."""
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if self.rw_pin:
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self.rw_pin.setValue(0)
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if self._4bit:
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self.hal_write_4bits(value >> 4)
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self.hal_write_4bits(value)
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else:
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# unlike machine.Pin, onionGpio.OnionGpio.setValue needs us to convert to 0s & 1s ourselves
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self.d3_pin.setValue(int(bool(value & 0x08)))
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self.d2_pin.setValue(int(bool(value & 0x04)))
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self.d1_pin.setValue(int(bool(value & 0x02)))
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self.d0_pin.setValue(int(bool(value & 0x01)))
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self.hal_write_4bits(value >> 4)
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def hal_write_4bits(self, nibble):
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"""Writes 4 bits of data to the LCD."""
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self.d7_pin.setValue(int(bool(nibble & 0x08)))
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self.d6_pin.setValue(int(bool(nibble & 0x04)))
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self.d5_pin.setValue(int(bool(nibble & 0x02)))
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self.d4_pin.setValue(int(bool(nibble & 0x01)))
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self.hal_pulse_enable()
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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(usecs/1E6) # Uses the standard python library time module for onion omega

‎lcd/onion_lcd_gpio_test.py‎

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"""Implements a HD44780 character LCD connected via Onion Omega GPIO pins."""
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from onion_lcd_gpio import GpioLcd
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from time import sleep, clock #Note: clock removed in python 3.8 (however onion distributes python 3.4)
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# https://docs.onion.io/omega2-docs/gpio-python-module.html#gpio-python-module
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# requires a python3 modification of the current standard onionGpio (as of 2021-11-20)
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from onionGpio import OnionGpio
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# Wiring used for this example:
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# tested with Onion omega2+
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#
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# 1 - Vss (aka Ground) - Connect to one of the ground pins on you pyboard.
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# 2 - VDD - I connected to VIN which is 5 volts when your pyboard is powered via USB
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# 3 - VE (Contrast voltage) - I'll discuss this below
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# 4 - RS (Register Select) connect to gpio pin 2 (as per call to GpioLcd)
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# 5 - RW (Read/Write) - connect to ground
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# 6 - EN (Enable) connect to gpio pin 3 (as per call to GpioLcd)
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# 7 - D0 - leave unconnected
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# 8 - D1 - leave unconnected
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# 9 - D2 - leave unconnected
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# 10 - D3 - leave unconnected
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# 11 - D4 - connect to gpio pin 0 (as per call to GpioLcd)
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# 12 - D5 - connect to gpio pin 1 (as per call to GpioLcd)
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# 13 - D6 - connect to gpio pin 6 (as per call to GpioLcd)
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# 14 - D7 - connect to gpio pin 19 (as per call to GpioLcd)
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# 15 - A (BackLight Anode) - Connect to VIN
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# 16 - K (Backlight Cathode) - Connect to Ground
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#
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# On 14-pin LCDs, there is no backlight, so pins 15 & 16 don't exist.
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#
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# The Contrast line (pin 3) typically connects to the center tap of a
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# 10K potentiometer, and the other 2 legs of the 10K potentiometer are
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# connected to pins 1 and 2 (Ground and VDD)
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#
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# See: https://docs.onion.io/omega2-docs/using-gpios.html#boot-pins
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# for more info on which pins can be used freely
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# note that pins must be in gpio mode, see the onion docs
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#
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#
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def test_main():
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"""Test function for verifying basic functionality."""
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print("Running test_main")
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lcd = GpioLcd(rs_pin=OnionGpio(2),
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enable_pin=OnionGpio(3),
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d4_pin=OnionGpio(0),
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d5_pin=OnionGpio(1),
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d6_pin=OnionGpio(6),
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d7_pin=OnionGpio(19),
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num_lines=2, num_columns=16)
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lcd.putstr("It Works!\nSecond Line\nThird Line\nFourth Line")
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sleep(3)
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lcd.clear()
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count = 0
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while True:
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lcd.move_to(0, 0)
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lcd.putstr("%7d" % (int(round(clock(),6)*1E6) // 1000))
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sleep(1)
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count += 1
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if __name__ == '__main__':
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test_main()

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