ChibiOS 2.6.8, until I can figure out where to get it from git.

firmware/chibios/demos/AVR-ATmega128-GCC/lcd.c

@@ -0,0 +1,97 @@
+/*
+    ChibiOS/RT - Copyright (C) 2006-2013 Giovanni Di Sirio
+
+    Licensed under the Apache License, Version 2.0 (the "License");
+    you may not use this file except in compliance with the License.
+    You may obtain a copy of the License at
+
+        http://www.apache.org/licenses/LICENSE-2.0
+
+    Unless required by applicable law or agreed to in writing, software
+    distributed under the License is distributed on an "AS IS" BASIS,
+    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+    See the License for the specific language governing permissions and
+    limitations under the License.
+*/
+
+#include "ch.h"
+#include "hal.h"
+#include "lcd.h"
+
+static void e_pulse(void) {
+  volatile uint8_t i;
+
+  PORTC |= PORTC_44780_E_MASK;
+  for (i = 0; i < ELOOPVALUE; i++);
+    ;
+  PORTC &= ~PORTC_44780_E_MASK;
+}
+
+static void wait_not_busy(void) {
+
+  chThdSleep(2);
+}
+
+/*
+ * 44780 soft reset procedure.
+ */
+void lcdInit(void) {
+
+  PORTC = (PORTC & ~(PORTC_44780_DATA_MASK | PORTC_44780_RS_MASK |
+                     PORTC_44780_E_MASK | PORTC_44780_RW_MASK)) |
+          (LCD_CMD_INIT8 & PORTC_44780_DATA_MASK);
+  chThdSleep(50);
+  e_pulse();
+  chThdSleep(10);
+  e_pulse();
+  chThdSleep(2);
+  e_pulse();
+  wait_not_busy();
+  PORTC = (PORTC & ~(PORTC_44780_DATA_MASK | PORTC_44780_RS_MASK |
+                     PORTC_44780_E_MASK | PORTC_44780_RW_MASK)) |
+          (LCD_CMD_INIT4 & PORTC_44780_DATA_MASK);
+  e_pulse();
+  lcdCmd(LCD_CMD_INIT4);
+  lcdCmd(LCD_SET_DM | LCD_DM_DISPLAY_ON);
+  lcdCmd(LCD_SET_INCREMENT_MODE);
+}
+
+/*
+ * Sends a command byte to the 44780.
+ */
+void lcdCmd(uint8_t cmd) {
+
+  wait_not_busy();
+  PORTC = (PORTC | PORTC_44780_DATA_MASK) & (cmd |
+                                             (0x0F & ~PORTC_44780_RS_MASK));
+  e_pulse();
+  PORTC = (PORTC | PORTC_44780_DATA_MASK) & ((cmd << 4) |
+                                             (0x0F & ~PORTC_44780_RS_MASK));
+  e_pulse();
+}
+
+/*
+ * Writes a char on the LCD at the current position.
+ */
+void lcdPutc(char c) {
+  uint8_t b;
+
+  wait_not_busy();
+  b = c | 0x0F;
+  PORTC = (PORTC | PORTC_44780_DATA_MASK | PORTC_44780_RS_MASK) &
+          (c | 0x0F);
+  e_pulse();
+  PORTC = (PORTC | PORTC_44780_DATA_MASK | PORTC_44780_RS_MASK) &
+          ((c << 4) | 0x0F);
+  e_pulse();
+}
+
+/*
+ * Writes a string on the LCD at an absolute address.
+ */
+void lcdPuts(uint8_t pos, char *p) {
+
+  lcdCmd(LCD_SET_DDRAM_ADDRESS | pos);
+  while (*p)
+    lcdPutc(*p++);
+}