Checkpoint, have "HELLO WORLD"

python/samples/lcd1602.py

@@ -0,0 +1,101 @@
+"""
+Example for LCD1602, in which a PCF8574 I/O expander drives a HD44780
+Available from various vendors.
+"""
+
+import sys
+import time
+import struct
+
+from i2cdriver import I2CDriver
+
+class HD44780:
+
+    def __init__(self, i2, a = 0x27):
+        self.i2 = i2
+        self.a = a
+
+        # Command (0) / Data (1) (aka RS) (D0)
+        # R/W                             (D1)
+        # Enable/CLK                      (D2) 
+        # Backlight control               (D3)
+
+        self.nybble(3)
+        self.nybble(3)
+        self.nybble(3)
+        self.nybble(2)
+
+        self.cmd(0x28)  # 2 lines, 5x8 dot matrix
+        self.cmd(0x0c)  # display on
+        self.cmd(0x06)  # inc cursor to right when writing and don't scroll
+        self.cmd(0x80)  # set cursor to row 1, column 1
+
+        time.sleep(.2)
+        self.data(0x42)
+
+        while 0:
+            self.port(0)
+            time.sleep(.1)
+            self.port(8)
+            time.sleep(.1)
+        # self.clear()
+
+    def clear(self):
+        """ Blank / Reset LCD """
+        self.cmd(0x33) # $33 8-bit mode
+        self.cmd(0x32) # $32 8-bit mode
+        self.cmd(0x28) # $28 8-bit mode
+        self.cmd(0x0C | 3) # $0C 8-bit mode
+        self.cmd(0x06) # $06 8-bit mode
+        self.cmd(0x01) # $01 8-bit mode
+
+    def port(self, *bb):
+        # Write byte to port
+        if 0:
+            self.i2.start(self.a, 0)
+            self.i2.write(bb)
+            self.i2.stop()
+            time.sleep(.000500)
+            time.sleep(.050)
+        else:
+            for b in bb:
+                self.i2.start(self.a, 0)
+                self.i2.write([b])
+                self.i2.stop()
+                time.sleep(.005000)
+
+    def nybble(self, n, rs = 0):
+        print("   nyb %x" % n)
+        bl = 8 | rs
+        self.port(
+            bl | (n << 4),
+            bl | (n << 4) | 4,
+            bl | (n << 4)
+        )
+
+    def cmd(self, b):
+        print("cmd %02x" % b)
+        self.nybble(b >> 4)
+        self.nybble(b & 0xf)
+        time.sleep(.004100)
+
+    def data(self, b):
+        print("DAT %02x" % b)
+        self.nybble(b >> 4, 1)
+        self.nybble(b & 0xf, 1)
+        time.sleep(.004100)
+
+    def message(self, text):
+        """ Send string to LCD. Newline wraps to second line"""
+
+        for char in text:
+            if char == '\n':
+                self.cmd(0xC0) # next line
+            else:
+                self.data(ord(char))
+
+if __name__ == '__main__':
+    i2 = I2CDriver(sys.argv[1])
+    i2.scan()
+    d = HD44780(i2)
+    d.message("HELLO WORLD")