Adds working LCD driver
This commit is contained in:
Shawn Nock
parent
fef826f1d3
commit
1924f027c6
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@ -1,5 +1,6 @@
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import time
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from smbus import SMBus
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from twisted.internet import reactor
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ADDR = 0x20
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BUS = 1
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@ -7,8 +8,8 @@ BUS = 1
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LCD_DATA = 1
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LCD_CMD = 0
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LCD_LINE_ADDR = {0: 0x80,
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1: 0xc0}
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LCD_LINE_ADDR = {0: 0x0,
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1: 0x40}
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# Timing constants
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E_PULSE = 0.0005
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@ -36,7 +37,31 @@ DB7 = (1 << 6)
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LCD_BACKLIGHT = (1 << 7)
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# HD44780 Commands
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LCD_CLEAR = 1
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LCD_HOME = (1 << 1)
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LCD_ENTRY_MODE = (1 << 2)
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CURSOR_INCR = (1 << 1)
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CURSOR_DECR = (0 << 1)
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SHIFT_ENABLE = (1 << 0)
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SHIFT_DISABLE = (0 << 0)
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DISPLAY_CTRL = (1 << 3)
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DISPLAY_ON = (1 << 2)
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DISPLAY_OFF = (0 << 2)
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CURSOR_ON = (1 << 1)
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CURSOR_OFF = (0 << 1)
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BLINK_ON = (1 << 0)
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BLINK_OFF = (0 << 0)
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FUNC_SET = (1 << 4)
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DATA_4BIT = (1 << 3)
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DATA_8BIT = (0 << 3)
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TWO_LINES = (1 << 2)
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ONE_LINE = (0 << 2)
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SET_ADDRESS = (1 << 7)
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class LCD(object):
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def __init__(self, addr=ADDR):
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@ -48,58 +73,71 @@ class LCD(object):
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def _init_mcp(self):
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# Set MCP23008 pins as outputs
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self._write_reg(IODIR, 0x00)
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# Disable incrementing pointer
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self._write_reg(IOCON, IOCON_SREAD)
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# Enable Backlight
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self._write_reg(0x09, 1 << 7)
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def _write4(self, bits):
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message = (bits << 3) | LCD_BACKLIGHT
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self.bus.write_byte(self.addr, message)
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self._latch(message)
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def write_cmd(self, byte):
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self._write4((byte & 0xf0) >> 4)
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self._write4((byte & 0x0f))
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def _init_hd44780(self):
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# Initialize, set to 4bit mode
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self._write4(DB4|DB5)
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# Again, this time with feeling!
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self._write4(DB4|DB5)
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# Again, this time with feeling!
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self._write4(DB4|DB5)
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self._write4(DB5)
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self.write_cmd((DB5 << 4) | DB7)
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self.write_cmd(1) # Clear Display
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self.write_cmd(0 | (DB4 | DB5 | DB6 | DB7)) # Display ON, Cursor ON, Cursor Blinking
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self.write_cmd(0 | (DB5 | DB6)) # Entry Mode
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# Now we're in 4bit mode, move up to normal commands
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# Function Set
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self.write_cmd(FUNC_SET | TWO_LINES | DATA_4BIT) # 2 lines, 4bit
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# Clear Display
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self.write_cmd(LCD_CLEAR) # Clear Display
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self.write_cmd(LCD_HOME) # Home Display
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self.write_cmd(DISPLAY_CTRL | DISPLAY_ON) # Display ON
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self.write_cmd(LCD_ENTRY_MODE | CURSOR_INCR) # Entry Mode
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def _write4(self, bits, data=False):
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# No shift, use DB* macros
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message = bits | LCD_BACKLIGHT
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if data:
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message |= RS
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else:
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message &= ~RS
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self._write_reg(GPIO, message | ENABLE)
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self._latch(message)
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def write_cmd(self, byte, data=False):
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# Shifts the bytes up, DB* macros don't work
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high = (byte & 0xf0) >> 4
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low = byte & 0x0f
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assert byte == (high << 4) | low
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self._write4(high << 3, data)
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self._write4(low << 3, data)
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def _write_data(self, byte):
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self.write_cmd(byte, data=True)
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def _write_reg(self, reg, val):
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self.bus.write_byte_data(self.addr, reg, val)
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# def _write(self, byte, backlight=LCD_BACKLIGHT_ON, mode=0):
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# bits_high = (mode << 1) | ((byte & 0xF0) << 3) | backlight
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# bits_low = (mode << 1) | ((byte & 0xf) << 3) | backlight
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# self.bus.write(self.addr, bits_high)
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# self._latch(bits_high)
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# self.bus.write(self.addr, bits_low)
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# self._latch(bits_low)
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def _latch(self, bits):
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time.sleep(E_DELAY)
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self.bus.write_byte(self.addr, bits | ENABLE)
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time.sleep(E_PULSE)
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self.bus.write_byte(self.addr, (bits & ~ENABLE))
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self._write_reg(GPIO, bits & ~ENABLE)
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time.sleep(E_DELAY)
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# def write(self, line, string):
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# string = string.ljust(LCD_WIDTH, " ")[:LCD_WIDTH]
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# self._write(line)
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# for i in range(LCD_WIDTH):
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# self.write_cmd(ord(string[i]) | RS)
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def write(self, line, string):
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self.write_cmd(SET_ADDRESS | LCD_LINE_ADDR[line])
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string = string.ljust(LCD_WIDTH, " ")[:LCD_WIDTH]
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for i in range(LCD_WIDTH):
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self._write_data(ord(string[i]))
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def shutdown(self):
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self.write_cmd(DISPLAY_CTRL|DISPLAY_OFF)
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self._write_reg(GPIO, 0) # Turn off backlight
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LCD_SINGLETON = LCD()
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def lcd_write_status(status):
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return
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lines = status.split('\n')[:2]
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for i in range(len(lines)):
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LCD_SINGLETON.write(LCD_LINE_ADDR[i], lines[i])
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LCD_SINGLETON.write(i, lines[i])
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reactor.addSystemEventTrigger('before', 'shutdown',
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LCD_SINGLETON.shutdown)
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