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Re: [Sdcc-user] 16*4 LCD - 4bit mode
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From: Vikram T. <vik...@ya...> - 2005-08-30 17:57:45
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Hi
Actually I am trying to interface an 16*4 LCD to
AT89c51 using Pcf8574-I2C-io chip.
But have problem in making simple io to work.
I tried the following code
#include <stdio.h>
#include <AT89X51.H>
#include <intrins.h>
#define CPUCLKHZ 11059200
#define DELAY_CPU_CLOCK CPUCLKHZ / 12 // 8051
clock rate (X1 mode)
#define DELAY_CONST 9.114584e-5 // Delay
routine constant
#define DELAY_MULTPLR (unsigned char)(DELAY_CONST *
DELAY_CPU_CLOCK)
void delay_ms(volatile unsigned int count)
{
for(count *= DELAY_MULTPLR; count > 0; count--);
}
//#define SCL P3_6 // I2C Clock
//#define SDA P3_5 // I2C Data
#define SDA P2_0 // I2C Clock
#define SCL P2_1 // I2C Data
#define nop _nop_ ()
#define XIO_ID 0x76 // Device identifier of
the I/O-Expander (PCF8574)
//#define XIO_ID_LCD 0x40
//#define XIO_ID_OUTPUT 0x41
//#define XIO_ID_INPUT 0x42
//#define XIO_ID_EXTRA 0x43
#define READ 0x01 // Alias for read
command bit
#define WRITE 0x00 // Alias for write
command bit
void i2c_delay(void)
{
EA = 0; // Disable all interrupts for a accurate
timing
// Valid for fq = 24MHz -> Tcycle = 500ns -> 10 x
nop
nop;
nop;
nop;
nop;
nop;
nop;
nop;
nop;
nop;
nop;
EA = 1; // Enable all interrupts
return;
}
void i2c_start(void)
{
EA = 0; // Disable all interrupts for a
accurate timing
// Force defined state of SCL and SDA
SCL = 1; // Release SCL
SDA = 1; // Release SDA
i2c_delay(); // Force 5µs-delay
// Generate START condition
SDA = 0;
i2c_delay(); // Force 5µs-delay
SCL = 0;
EA = 1; // Enable all interrupts
// I2C Busy
return;
}
void i2c_stop(void)
{
EA = 0; // Disable all interrupts for a
accurate timing
// Generate STOP condition
SDA = 0;
i2c_delay(); // Force 5µs-delay
SCL = 1; // Release SCL
i2c_delay(); // Force 5µs-delay
SDA = 1; // Release SDA
EA = 1; // Enable all interrupts
// I2C Idle
return;
}
void i2c_ack(void)
{
EA = 0; // Disable all interrupts for a
accurate timing
// Generate ACK
SDA = 0;
SCL = 1; // Release SCL
while(SCL == 0); // Synchronize clock
i2c_delay(); // Force 5µs-delay
SCL = 0; // Force a clock cycle
EA = 1; // Enable all interrupts
return;
}
void i2c_nack(void)
{
EA = 0; // Disable all interrupts for a
accurate timing
// Generate NACK
SDA = 1; // Release SDA
SCL = 1; // Release SCL
while(SCL == 0); // Synchronize clock
i2c_delay(); // Force 5µs-delay
SCL = 0; // Force a clock cycle
EA = 1; // Enable all interrupts
return;
}
unsigned char i2c_check(void)
{
EA = 0; // Disable all interrupts for a
accurate timing
SDA = 1; // Release SDA
SCL = 1; // Release SCL
while(SCL == 0); // Synchronize clock
i2c_delay(); // Force 5µs-delay
if (SDA) // SDA is high
{
SCL = 0; // Force a clock cycle
EA = 1; // Enable all interrupts
return(1); // No acknowledge from Slave
}
SCL = 0; // Force a clock cycle
EA = 1; // Enable all interrupts
return(0); // Acknowledge from Slave
}
void errormsg(unsigned char ascii)
{
putchar('§');
putchar(ascii);
puts("-error occured !");
putchar(0x0A);
putchar(0x0D);
putchar(0x07);
return;
}
unsigned char i2c_write(unsigned char value)
{
idata unsigned char counter = 0; // Bitcounter
EA = 0; // Disable all
interrupts for a accurate timing
for ( counter = 0; counter < 8; counter++ )
{
SDA = (bit)((value&0x80) >> 7); // Set SDA to value
of MSB
SCL = 1; // Release SCL
while(SCL == 0); // Synchronize clock
i2c_delay(); // Force 5µs-delay
SCL = 0; // Force a clock
cycle
value <<= 1; // Prepare next bit
for transmission
}
EA = 1; // Enable all
interrupts
// Generate a 9. clock cycle and check ACK from SLAVE
// Return the result
return(i2c_check());
}
unsigned char i2c_read(void)
{
idata unsigned char result = 0; // Returnvalue
with read I2C byte
idata unsigned char counter = 0; // Bitcounter
EA = 0; // Disable all interrupts
for a accurate timing
for ( counter = 0; counter < 8; counter++ )
{
SDA = 1; // Release SDA
SCL = 1; // Release SCL
while(SCL == 0); // Synchronize clock
i2c_delay(); // Force 5µs-delay
result <<= 1; // Shift left the result
if (SDA)
result |= 0x01; // Set actual SDA state to LSB
SCL = 0; // Force a clock cycle
i2c_delay(); // Force 5µs-delay
}
EA = 1; // Enable all interrupts
// ACK or NACK from MASTER must be generated outside
this routine
return(result);
}
void XIO_write(unsigned char content)
{
i2c_start(); // Generate START condition
// Send SLAVE adress with write request
if ( i2c_write(XIO_ID|WRITE) )
{
errormsg('K');
return;
}
// Send content byte
if ( i2c_write(content) )
{
errormsg('L');
return;
}
i2c_stop(); // Generate STOP condition
return;
}
unsigned char XIO_read(void)
{
unsigned char result;
i2c_start(); // Generate START condition
// Send SLAVE adress with write request
if ( i2c_write(XIO_ID|WRITE) )
{
errormsg('K');
return(0);
}
// Set all pins high to be used as inputs
if ( i2c_write(0xFF) )
{
errormsg('L');
return(0);
}
i2c_stop(); // Generate STOP condition
i2c_start(); // Generate START condition
// Send SLAVE adress with read request
if ( i2c_write(XIO_ID|READ) )
{
errormsg('M');
return(0);
}
// Read port
result = i2c_read();
i2c_stop(); // Generate STOP condition
return(result);
}
void main ()
{
SCON = 0x52;
TMOD |= 0x20;
PCON |= 0x80;
TH1 = TL1 = 250;
TR1 = 1;
while(1)
{
delay_ms(90000);
delay_ms(90000);
delay_ms(90000);
XIO_write(0x00);
XIO_write(0x00);
delay_ms(90000);
delay_ms(90000);
delay_ms(90000);
XIO_write(0xFF);
XIO_write(0xFF);
P0 = ~P0;
P1 = ~P1;
P2 = ~P2;
puts("Hello World");
}
}
but was getting error K error ocured.
dono where i am wrong.
Thanks in advance
Vikram
--- Gernot Fink <g....@gm...> wrote:
> On Wed, 03 Aug 2005, you wrote:
> > hi all
> >
> > can any one provide the initialize details for
> 16*4
> > LCD
> > I have connected the Lcd to port 2 in 4bit mode
> >
> > P2.0 <----> D4
> > P2.1 <----> D5
> > P2.2 <----> D6
> > P2.3 <----> D7
> > P2.4 <----> EN
> > P2.5 <----> A0 (0 means command, 1 means
> data)
> >
>
> Hallo,
>
> the delays are calculated for 9.216 MHZ.
> There are 2 delays, a long for cmds<4 and a short.
> This programm is so small and dirty to fit in a
> at89c2051 (on port1)
>
> #define lcd_putc(i) lcd_out(i)
> bit lcddata;
>
> void lcd_out(unsigned char c)
> {
>
> P2&=0x80;
> P2_5=lcddata;
> P2|=(c>>4);
> P2_4=1;
> P2_4=0;
> P2&=0xc0;
> P2|=c&15;
> P2_4=1;
> P2_4=0;
>
> P2_5=0;
> P2|=0x1f;
>
> if(lcddata==0&&c<4)_asm
> mov a,#225
> 00001$:
> nop
> nop
> nop
> nop
> dec a
> jnz 00001$
> _endasm;
> _asm
> mov a,#12
> 00100$:
> dec ACC
> jnz 00100$
> _endasm;
> }
>
> code unsigned char
> lcdinitstring[]={0x28,0x28,12,6,1,0};
> void lcd_cmd(unsigned char c)
> {
> lcddata=0;
> lcd_out(c);
> lcddata=1;
> }
> void lcd_init(void)
> {
> lcddata=0;
> lcd_putc(0x28);
> lcd_puts(lcdinitstring);
> lcddata=1;
> }
> void lcd_puts(unsigned char code *c)
> {
> while (*c)
> {
> lcd_putc(*(c++));
> }
> }
> void lcd_goto(unsigned char c)
> {
> lcddata=0;
> lcd_out(c+128);
> lcddata=1;
> }
>
>
>
> --
> MFG Gernot
>
>
>
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