diff --git a/src/LiquidCrystal.cpp b/src/LiquidCrystal.cpp
index 8c6cdf0..276d0d5 100644
--- a/src/LiquidCrystal.cpp
+++ b/src/LiquidCrystal.cpp
@@ -5,20 +5,24 @@
#include <inttypes.h>
#include "Arduino.h"
+// Minimum time between falling edges of E (enable pin to do writes)
+#define _LCD_COMMAND_DELAY 40
+#define _MAX_COMMAND_DELAY 200
+
// When the display powers up, it is configured as follows:
//
// 1. Display clear
-// 2. Function set:
-// DL = 1; 8-bit interface data
-// N = 0; 1-line display
-// F = 0; 5x8 dot character font
-// 3. Display on/off control:
-// D = 0; Display off
-// C = 0; Cursor off
-// B = 0; Blinking off
-// 4. Entry mode set:
-// I/D = 1; Increment by 1
-// S = 0; No shift
+// 2. Function set:
+// DL = 1; 8-bit interface data
+// N = 0; 1-line display
+// F = 0; 5x8 dot character font
+// 3. Display on/off control:
+// D = 0; Display off
+// C = 0; Cursor off
+// B = 0; Blinking off
+// 4. Entry mode set:
+// I/D = 1; Increment by 1
+// S = 0; No shift
//
// Note, however, that resetting the Arduino doesn't reset the LCD, so we
// can't assume that its in that state when a sketch starts (and the
@@ -57,22 +61,22 @@ void LiquidCrystal::init(uint8_t fourbitmode, uint8_t rs, uint8_t rw, uint8_t en
_rs_pin = rs;
_rw_pin = rw;
_enable_pin = enable;
-
+
_data_pins[0] = d0;
_data_pins[1] = d1;
_data_pins[2] = d2;
- _data_pins[3] = d3;
+ _data_pins[3] = d3;
_data_pins[4] = d4;
_data_pins[5] = d5;
_data_pins[6] = d6;
- _data_pins[7] = d7;
+ _data_pins[7] = d7;
if (fourbitmode)
_displayfunction = LCD_4BITMODE | LCD_1LINE | LCD_5x8DOTS;
- else
+ else
_displayfunction = LCD_8BITMODE | LCD_1LINE | LCD_5x8DOTS;
-
- begin(16, 1);
+ _comm_delay = _LCD_COMMAND_DELAY; // Default command delay
+ begin(16, 1);
}
void LiquidCrystal::begin(uint8_t cols, uint8_t lines, uint8_t dotsize) {
@@ -81,7 +85,7 @@ void LiquidCrystal::begin(uint8_t cols, uint8_t lines, uint8_t dotsize) {
}
_numlines = lines;
- setRowOffsets(0x00, 0x40, 0x00 + cols, 0x40 + cols);
+ setRowOffsets(0x00, 0x40, 0x00 + cols, 0x40 + cols);
// for some 1 line displays you can select a 10 pixel high font
if ((dotsize != LCD_5x8DOTS) && (lines == 1)) {
@@ -90,47 +94,47 @@ void LiquidCrystal::begin(uint8_t cols, uint8_t lines, uint8_t dotsize) {
pinMode(_rs_pin, OUTPUT);
// we can save 1 pin by not using RW. Indicate by passing 255 instead of pin#
- if (_rw_pin != 255) {
+ if (_rw_pin != 255) {
pinMode(_rw_pin, OUTPUT);
}
pinMode(_enable_pin, OUTPUT);
-
+
// Do these once, instead of every time a character is drawn for speed reasons.
for (int i=0; i<((_displayfunction & LCD_8BITMODE) ? 8 : 4); ++i)
{
pinMode(_data_pins[i], OUTPUT);
- }
+ }
// SEE PAGE 45/46 FOR INITIALIZATION SPECIFICATION!
// according to datasheet, we need at least 40ms after power rises above 2.7V
// before sending commands. Arduino can turn on way before 4.5V so we'll wait 50
- delayMicroseconds(50000);
+ delayMicroseconds(50000);
// Now we pull both RS and R/W low to begin commands
digitalWrite(_rs_pin, LOW);
digitalWrite(_enable_pin, LOW);
- if (_rw_pin != 255) {
+ if (_rw_pin != 255) {
digitalWrite(_rw_pin, LOW);
}
-
+
//put the LCD into 4 bit or 8 bit mode
if (! (_displayfunction & LCD_8BITMODE)) {
// this is according to the hitachi HD44780 datasheet
// figure 24, pg 46
// we start in 8bit mode, try to set 4 bit mode
- write4bits(0x03);
+ writebits(0x03, 4, 1);
delayMicroseconds(4500); // wait min 4.1ms
// second try
- write4bits(0x03);
+ writebits(0x03, 4, 1);
delayMicroseconds(4500); // wait min 4.1ms
-
+
// third go!
- write4bits(0x03);
+ writebits(0x03, 4, 1);
delayMicroseconds(150);
// finally, set to 4-bit interface
- write4bits(0x02);
+ writebits(0x02, 4, 1);
} else {
// this is according to the hitachi HD44780 datasheet
// page 45 figure 23
@@ -148,10 +152,10 @@ void LiquidCrystal::begin(uint8_t cols, uint8_t lines, uint8_t dotsize) {
}
// finally, set # lines, font size, etc.
- command(LCD_FUNCTIONSET | _displayfunction);
+ command(LCD_FUNCTIONSET | _displayfunction);
// turn the display on with no cursor or blinking default
- _displaycontrol = LCD_DISPLAYON | LCD_CURSOROFF | LCD_BLINKOFF;
+ _displaycontrol = LCD_DISPLAYON | LCD_CURSOROFF | LCD_BLINKOFF;
display();
// clear it off
@@ -194,7 +198,7 @@ void LiquidCrystal::setCursor(uint8_t col, uint8_t row)
if ( row >= _numlines ) {
row = _numlines - 1; // we count rows starting w/0
}
-
+
command(LCD_SETDDRAMADDR | (col + _row_offsets[row]));
}
@@ -260,6 +264,7 @@ void LiquidCrystal::noAutoscroll(void) {
command(LCD_ENTRYMODESET | _displaymode);
}
+
// Allows us to fill the first 8 CGRAM locations
// with custom characters
void LiquidCrystal::createChar(uint8_t location, uint8_t charmap[]) {
@@ -270,6 +275,24 @@ void LiquidCrystal::createChar(uint8_t location, uint8_t charmap[]) {
}
}
+
+/* New method that if default command delay is not long enough
+ to set a new value between
+ _LCD_COMMAND_DELAY (default 40 us)
+ _MAX_COMMAND_DELAY (default 200 us)
+
+ Should be called before you call begin method
+
+ returns 0 for success
+ -1 for error (invalid parameter)
+*/
+int LiquidCrystal::setCommandDelay( uint8_t delay ) {
+ if( delay >= _LCD_COMMAND_DELAY && delay <= _MAX_COMMAND_DELAY ) {
+ _comm_delay = delay;
+ return 0;
+ }
+return -1;
+}
/*********** mid level commands, for sending data/cmds */
inline void LiquidCrystal::command(uint8_t value) {
@@ -288,39 +311,56 @@ void LiquidCrystal::send(uint8_t value, uint8_t mode) {
digitalWrite(_rs_pin, mode);
// if there is a RW pin indicated, set it low to Write
- if (_rw_pin != 255) {
+ if (_rw_pin != 255) {
digitalWrite(_rw_pin, LOW);
}
-
+
if (_displayfunction & LCD_8BITMODE) {
- write8bits(value);
+ writebits(value, 8, 0);
} else {
- write4bits(value>>4);
- write4bits(value);
+ writebits(value>>4, 4, 0);
+ writebits(value, 4, 1);
}
}
-void LiquidCrystal::pulseEnable(void) {
- digitalWrite(_enable_pin, LOW);
- delayMicroseconds(1);
+
+/* pulseEnable once data and RS set pulse enable line to send data in 4/8 bit mode
+
+ Checks when last falling edge of enable was and if sending a NEW command
+ delays for time to get up to _comm_delay to ensure controller ready
+
+ When in 4 bit mode 2nd nibble can be sent at minimum delay for Enable high
+ time delay 1us
+
+ Parameter type - 0 = new command start
+ 1 = 2nd nibble for 4 bit mode (needs 1us delay
+ NOT _comm_delay)
+*/
+void LiquidCrystal::pulseEnable(uint8_t type) {
+ unsigned long _delaymicros;
+
digitalWrite(_enable_pin, HIGH);
- delayMicroseconds(1); // enable pulse must be >450ns
+ _delaymicros = micros( ) - _oldmicros; // PREVIOUS commands need > 37us to settle
+ if( _delaymicros < _comm_delay && type == 0 )
+ delayMicroseconds( _comm_delay - _delaymicros ); // wait time for delay
+ else
+ delayMicroseconds(1); // enable pulse HIGH must be >450ns
digitalWrite(_enable_pin, LOW);
- delayMicroseconds(100); // commands need > 37us to settle
+ _oldmicros = micros( ); // save time to check next time
}
-void LiquidCrystal::write4bits(uint8_t value) {
- for (int i = 0; i < 4; i++) {
- digitalWrite(_data_pins[i], (value >> i) & 0x01);
- }
- pulseEnable();
-}
+/* writebits transfer correct number of bits to output and then call pulse enable
-void LiquidCrystal::write8bits(uint8_t value) {
- for (int i = 0; i < 8; i++) {
+ Parameters value - 4 or 8 bits to send
+ in 4 bit mode shift top 4 bits right before calling
+ bits - value 4 or 8 for bits to send
+ type - 0 = new command start
+ 1 = 2nd nibble for 4 bit mode (needs 1us delay NOT _MIN_WRITE_DELAY
+*/
+void LiquidCrystal::writebits(uint8_t value, uint8_t bits, uint8_t type) {
+ for (int i = 0; i < bits; i++) {
digitalWrite(_data_pins[i], (value >> i) & 0x01);
}
-
- pulseEnable();
+ pulseEnable( type );
}
diff --git a/src/LiquidCrystal.h b/src/LiquidCrystal.h
index da950ce..a0f7280 100644
--- a/src/LiquidCrystal.h
+++ b/src/LiquidCrystal.h
@@ -58,7 +58,7 @@ class LiquidCrystal : public Print {
void init(uint8_t fourbitmode, uint8_t rs, uint8_t rw, uint8_t enable,
uint8_t d0, uint8_t d1, uint8_t d2, uint8_t d3,
uint8_t d4, uint8_t d5, uint8_t d6, uint8_t d7);
-
+
void begin(uint8_t cols, uint8_t rows, uint8_t charsize = LCD_5x8DOTS);
void clear();
@@ -76,24 +76,25 @@ class LiquidCrystal : public Print {
void rightToLeft();
void autoscroll();
void noAutoscroll();
+ int setCommandDelay( uint8_t );
void setRowOffsets(int row1, int row2, int row3, int row4);
void createChar(uint8_t, uint8_t[]);
- void setCursor(uint8_t, uint8_t);
+ void setCursor(uint8_t, uint8_t);
virtual size_t write(uint8_t);
void command(uint8_t);
-
+
using Print::write;
private:
void send(uint8_t, uint8_t);
- void write4bits(uint8_t);
- void write8bits(uint8_t);
- void pulseEnable();
+ void writebits(uint8_t, uint8_t, uint8_t);
+ void pulseEnable( uint8_t );
uint8_t _rs_pin; // LOW: command. HIGH: character.
uint8_t _rw_pin; // LOW: write to LCD. HIGH: read from LCD.
uint8_t _enable_pin; // activated by a HIGH pulse.
uint8_t _data_pins[8];
+ uint8_t _comm_delay; // Delay between commands by default _LCD_COMMAND_DELAY
uint8_t _displayfunction;
uint8_t _displaycontrol;
@@ -103,6 +104,7 @@ class LiquidCrystal : public Print {
uint8_t _numlines;
uint8_t _row_offsets[4];
+ unsigned long _oldmicros;
};
#endif