Adds working LCD driver

software/trespassed/lcd.py

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