[En-Nut-Discussion] new to nutos usage
Paolo Simoncelli
simonp at email.it
Mon Jun 21 12:57:32 CEST 2010
Hi all,
sorry zvonko, but i have had no good luck with LCD displays
and ethernut, here is my experience:
At first i haven't been able to make Jose's code work,
it's using the builtin driver: (quite old post ...)
http://lists.egnite.de/pipermail/en-nut-discussion/2007-March/007990.html
maybe there's an open bug for that:
http://sourceforge.net/tracker/?func=detail&aid=2995417&group_id=34079&atid=410687
(BTW i will be glad to contribute for a fix ;-) )
Next i went to the code reported on "Ethernut application note 001"
but it did not even compiled at first (some editing needed,
maybe it refers to old NutOS/Ethernut versions) anyway no luck at all :-(
So, based on appnote001 sw & hw wiring, i wrote my own code,
here follows a basic example, i have left the appnote001 comments
plus some spaghetti programming examples ;-)
sorry for the long post hope it will help ! ciao !
// -- LCD ------------------------------------------------------------
/*
Instruction Code Description
D7 D6 D5 D4 D3 D2 D1 D0
Clear display 0 0 0 0 0 0 0 1 Clears display and returns cursor to the home position (address 0). 1.64mS
Cursor home 0 0 0 0 0 0 1 * Returns cursor to home position (address 0). Also returns display being
shifted to the original position. DDRAM contents remains unchanged. 1.64mS
Entry mode set 0 0 0 0 0 1 I/D S Sets cursor move direction (I/D), specifies to shift the display (S).
These operations are performed during data read/write. 40uS
Display On/Off control 0 0 0 0 1 D C B Sets On/Off of all display (D), cursor On/Off (C) and blink of cursor
position character (B). 40uS
Cursor/display shift 0 0 0 1 S/C R/L * * Sets cursor-move or display-shift (S/C), shift direction (R/L). DDRAM
contents remains unchanged. 40uS
Function set 0 0 1 DL N F * * Sets interface data length (DL), number of display line (N) and character
font(F). 40uS
Set CGRAM address 0 1 CGRAM address Sets the CGRAM address. CGRAM data is sent and received after this
setting. 40uS
Set DDRAM address 1 DDRAM address Sets the DDRAM address. DDRAM data is sent and received after this
setting. 40uS
Read busy-flag and address counter 0 1 BF CGRAM / DDRAM address Reads Busy-flag (BF) indicating internal operation is being
performed and reads CGRAM or DDRAM address counter contents (depending on previous instruction). 0uS
Write to CGRAM or DDRAM 1 0 write data Writes data to CGRAM or DDRAM. 40uS
Read from CGRAM or DDRAM 1 1 read data Reads data from CGRAM or DDRAM. 40uS
Remarks:
*/
// HD44780 Commandset
// 01h Clear display
#define LCD_CLR 0 // DB0: clear display
// 02h or 03h Return cursor home
#define LCD_HOME 1 // DB1: return to home position
// 04h 05h 06h 07h Entry mode set
#define LCD_ENTRY_MODE 2 // DB2: set entry mode
#define LCD_ENTRY_INC 1 // DB1: increment
#define LCD_ENTRY_SHIFT 0 // DB2: shift
// 08h 09h 0Ah 0Bh 0Ch 0Dh 0Eh 0Fh Display/Cursor ON OFF
#define LCD_ON_CTRL 3 // DB3: turn lcd/cursor on
#define LCD_ON_DISPLAY 2 // DB2: turn display on
#define LCD_ON_CURSOR 1 // DB1: turn cursor on
#define LCD_ON_BLINK 0 // DB0: blinking cursor
#define LCD_MOVE 4 // DB4: move cursor/display
#define LCD_MOVE_DISP 3 // DB3: move display (0-> move cursor)
#define LCD_MOVE_RIGHT 2 // DB2: move right (0-> left)
#define LCD_FUNCTION 5 // DB5: function set
#define LCD_FUNCTION_8BIT 4 // DB4: set 8BIT mode (0->4BIT mode)
#define LCD_FUNCTION_2LINES 3 // DB3: two lines (0->one line)
#define LCD_FUNCTION_RE 2 // DB2: KS0073 Controller: Extended Register
#define LCD_FUNCTION_10DOTS 2 // DB2: 5x10 font (0->5x7 font)
#define LCD_FUNCTION_DS 1 // DB1: DisplayShift / DotScroll
#define LCD_FUNCTION_REV 0 // DB0: Reverse Display
#define LCD_EXT 3 // DB3: Extended Register Set
#define LCD_EXT_FONT 2 // DB2: Fontwidth: 5 / 6 Pixel
#define LCD_EXT_INVCURS 1 // DB1: Normal / Inverted Cursor
#define LCD_EXT_4LINES 0 // DB0: 1/2 Lines (normal) or 4Lines
#define LCD_CGRAM 6 // DB6: set CG RAM address
#define LCD_DDRAM 7 // DB7: set DD RAM address
// reading:
#define LCD_BUSY 7 // DB7: LCD is busy
// Initializing the LCD
// Some definitions first. As we find in the schematic, the LCD data port is connected to
// the upper 4 bits of port D.
#define LCD_DATA_DDR DDRD
#define LCD_DATA_PORT PORTD
// The two control lines are connected to bits 2 and 3 of port E.
#define LCD_CTRL_DDR DDRE
#define LCD_CTRL_PORT PORTE
#define LCD_CTRL_E PE3
#define LCD_CTRL_RS PE2
#define LCD_CTRL_RW PE4
// The LCD backlight is controlled by bit 6 on port B. (no backlight for now ...)
// #define LCD_LIGHT_DDR DDRB
// #define LCD_LIGHT_PORT PORTB
// #define LCD_LIGHT_BIT PB6
// Various delays
#define LCD_PWRON_DELAY 10
#define LCD_INIT_DELAY 4
#define LCD_LONG_DELAY 2
#define LCD_SHORT_DELAY 1
// Controlling the LCD
// The initialization routine already uses other subroutines to send data bytes and
// instructions to the LCD controller. Remember, that we drive the LCD in 4 bit mode. A
// special routine named LcdSendNibble will send the upper four bits of a character
// variable to the LCD data port. It sets the data lines and toggles the enable line.
static inline void LcdSendNibble(u_char nib)
{
outp((inp(LCD_DATA_PORT) & 0x0F) | (nib & 0xF0), LCD_DATA_PORT);
sbi(LCD_CTRL_PORT, LCD_CTRL_E);
asm volatile("nop\n\tnop");
cbi(LCD_CTRL_PORT, LCD_CTRL_E);
}
// Another routine called LcdSendByte sends a complete byte to the LCD controller by
// calling LcdSendNibble twice.
static inline void LcdSendByte(u_char ch, u_char xt)
{
LcdSendNibble(ch & 0xF0);
LcdSendNibble(ch << 4);
NutDelay(xt);
}
// Finally two additional routines are provided to either send an instruction or a data byte.
// Note, that only instructions need a specific delay time.
static void LcdWriteCmd(u_char cmd, u_char xt)
{
cbi(LCD_CTRL_PORT, LCD_CTRL_RS);
LcdSendByte(cmd, xt);
}
void LcdWriteChar(u_char ch)
{
sbi(LCD_CTRL_PORT, LCD_CTRL_RS);
LcdSendByte(ch,LCD_SHORT_DELAY);
}
void LcdWriteS(char *ch)
{
int i;
char c;
i=0;
while((c=ch[i++])>0){
LcdWriteChar(c);
}
}
// One of the most often used instructions to be send to the display is the clear
// command, which blanks the display. A special routine LcdClear will do this.
void LcdClear(void)
{
LcdWriteCmd(LCD_HOME,LCD_LONG_DELAY);
}
// The initialization routine uses another command routine named LcdSwitch, which
// switches on and off certain mode bits in the LCD controller.
void LcdSwitch(u_char on, u_char off)
{
// switch_control |= on & LCD_SWITCH_ALL;
// switch_control &= ~(off & LCD_SWITCH_ALL);
// LcdWriteCmd(switch_control, LCD_SHORT_DELAY);
}
// When calling LcdWriteChar instead of LcdWriteCmd, the characters of the specified
// codes are displayed and the cursor is automatically advanced to the next character
// position. In addition to the normal 7 bit ASCII character set the controller can display
// many other characters. It is even possible to define up to 8 custom characters, which
// however isn't explained in this application note.
// The LCD controller doesn't support cursor positioning on a specific column or row, but
// requires a memory address. This is not a big deal on 2 line displays, but address
// locations for the third and the second row depend on the number of columns being
// displayed. On 4 line displays with 16 columns each, the values are:
// #define LCD_ROW2_START 0x10
// #define LCD_ROW3_START 0x50
#define LCD_ROW2_START 0x14
#define LCD_ROW3_START 0x54
// Another routine called LcdSetCursor may be used to place the cursor to a specific
// position.
void LcdSetCursor(u_char row, u_char col)
{
u_char row_start[] = { 0x00, 0x40, LCD_ROW2_START, LCD_ROW3_START };
LcdWriteCmd(0x80 | row_start[row & 0x03] | col, LCD_SHORT_DELAY);
}
// routine called LcdSetCursor may be used to place the cursor to a specific
// position.
void LcdWriteAt(u_char row, u_char col, char *ch)
{
LcdSetCursor(row,col);
LcdWriteS(ch);
}
// A single routine is used to initialize all I/O lines and setup the LCD. Most notable is the
// for loop somewhere in the middle of the routine. When the LCD is powered up, the
// LCD controller will start in 8 bit mode. Switching it into 4 bit mode requires a specific
// command sequence. The loop will send three nibbles of value 3, two of value 2 and
// finally of value 8.
void LcdInit(void)
{
u_char i;
/*
* Set LCD read write low.
*/
cbi(LCD_CTRL_PORT, LCD_CTRL_RW);
sbi(LCD_CTRL_DDR, LCD_CTRL_RW);
/*
* Set LCD register select low.
*/
cbi(LCD_CTRL_PORT, LCD_CTRL_RS);
sbi(LCD_CTRL_DDR, LCD_CTRL_RS);
/*
* Set LCD enable low.
*/
cbi(LCD_CTRL_PORT, LCD_CTRL_E);
sbi(LCD_CTRL_DDR, LCD_CTRL_E);
/*
* Set direction register of LCD data port.
*/
sbi(LCD_DATA_DDR, 4);
sbi(LCD_DATA_DDR, 5);
sbi(LCD_DATA_DDR, 6);
sbi(LCD_DATA_DDR, 7);
/*
* Initialize for 4-bit operation.
*/
NutDelay(LCD_PWRON_DELAY);
for(i = 0;i<3; i++){
LcdSendNibble(0x30);
NutDelay(LCD_INIT_DELAY);
}
LcdSendNibble(0x20);
NutDelay(LCD_SHORT_DELAY);
/*
* 4-bit mode, 2/4 lines, 5x7 matrix.
*/
LcdWriteCmd(0x28,LCD_SHORT_DELAY);
/*
* Switch display, cursor and cursor blinking off.
*/
// LcdSwitch(0, LCD_SWITCH_ALL);
/*
* Clear display.
*/
LcdClear();
/*
* Increment cursor when writing.
*/
LcdWriteCmd((1<<LCD_ENTRY_MODE|1<<LCD_ENTRY_INC|0<<LCD_ENTRY_SHIFT),LCD_SHORT_DELAY);
/*
* Set cursor appearance
*/
LcdWriteCmd((1<<LCD_ON_CTRL|1<<LCD_ON_DISPLAY|1<<LCD_ON_CURSOR|1<<LCD_ON_BLINK),LCD_SHORT_DELAY);
/*
* Lit LED and switch display on.
*/
// sbi(LCD_LIGHT_DDR, LCD_LIGHT_BIT);
// sbi(LCD_LIGHT_PORT, LCD_LIGHT_BIT);
// LcdSwitch(LCD_SWITCH_DISPLAY, 0);
}
// -- END LCD --------------------------------------------------------
--
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