lcdmesg.c

#include<unistd.h>
#include<sys/types.h>
#include<sys/mman.h>
#include<stdio.h>
#include<fcntl.h>
#include<string.h>

#define GPIOBASE	0x80840000
#define MODELBASE       0x22000000
#define TS7300  0x03
#define PADR	0
#define PADDR	(0x10 / sizeof(unsigned int))
#define PAMASK  0x7F  
#define PCDR    (0x08 / sizeof(unsigned int))
#define PCDDR   (0x18 / sizeof(unsigned int))
#define PCMASK  0x01  
#define PHDR	(0x40 / sizeof(unsigned int))
#define PHDDR	(0x44 / sizeof(unsigned int))

// These delay values are calibrated for the EP9301 
// CPU running at 166 Mhz, but should work also at 200 Mhz
#define SETUP	15
#define PULSE	36
#define HOLD	22

#define COUNTDOWN(x)	asm volatile ( \
  "1:\n"\
  "subs %1, %1, #1;\n"\
  "bne 1b;\n"\
  : "=r" ((x)) : "r" ((x)) \
);

volatile unsigned int *model_ptr;
unsigned int model;
volatile unsigned int *gpio;
volatile unsigned int *phdr;
volatile unsigned int *phddr;
volatile unsigned int *pcdr;
volatile unsigned int *pcddr;
volatile unsigned int *padr;
volatile unsigned int *paddr;

void command(unsigned int);
void writechars(unsigned char *);
unsigned int lcdwait(void);
void lcdinit(void);

/* This program takes lines from stdin and prints them to the
 * 2 line LCD connected to the TS-7200 LCD header.  e.g
 *
 *    echo "hello world" | lcdmesg
 * 
 * It may need to be tweaked for different size displays
 */

int main(int argc, char **argv) {
	int i = 0;

	lcdinit();
	if (argc == 2) {
		writechars(argv[1]);
	}
	if (argc > 2) {
		writechars(argv[1]);
		lcdwait();
		command(0xa8); // set DDRAM addr to second row
		writechars(argv[2]);
	}
	if (argc >= 2) return 0;

	while(!feof(stdin)) {
		unsigned char buf[512];

		lcdwait();
		if (i) {
			// XXX: this seek addr may be different for different
			// LCD sizes!  -JO
			command(0xa8); // set DDRAM addr to second row
		} else {
			command(0x2); // return home
		}
		i = i ^ 0x1;
		if (fgets(buf, sizeof(buf), stdin) != NULL) {
			unsigned int len;
			buf[0x27] = 0;
			len = strlen(buf);
			if (buf[len - 1] == '\n') buf[len - 1] = 0;
			writechars(buf);
		}
	}
	return 0;
}

void lcdinit(void) {
	int fd = open("/dev/mem", O_RDWR|O_SYNC);

	gpio = (unsigned int *)mmap(0, getpagesize(), 
	  PROT_READ|PROT_WRITE, MAP_SHARED, fd, GPIOBASE);
	model_ptr = (unsigned int *)mmap(0, getpagesize(), 
	  PROT_READ|PROT_WRITE, MAP_SHARED, fd, MODELBASE);

	model = *model_ptr & 0x03;

	phdr = &gpio[PHDR];
	padr = &gpio[PADR];
	paddr = &gpio[PADDR];
	
	if(model == TS7300) {
		pcdr = &gpio[PCDR];
		pcddr = &gpio[PCDDR];
	}

	phddr = &gpio[PHDDR];
	
	if(model == TS7300) {
		*paddr & ~PAMASK;  // port A to inputs
		*pcddr & ~PCMASK;  // port C to inputs
//printf("CLEARED, paddr = 0x%x, pcddr = 0x%x\n", *paddr, *pcddr);
	} else {
		*paddr = 0x0;  // All of port A to inputs
	}

	*phddr |= 0x38; // bits 3:5 of port H to outputs
	*phdr &= ~0x18; // de-assert EN, de-assert RS
	usleep(15000);
	command(0x38); // two rows, 5x7, 8 bit
	usleep(4100);
	command(0x38); // two rows, 5x7, 8 bit
	usleep(100);
	command(0x38); // two rows, 5x7, 8 bit
	command(0x6); // cursor increment mode
	lcdwait();
	command(0x1); // clear display
	lcdwait();
	command(0xc); // display on, blink off, cursor off
	lcdwait();
	command(0x2); // return home
}

unsigned int lcdwait(void) {
	int i, dat, tries = 0;
	unsigned int ctrl = *phdr;

	if(model == TS7300) {
		*paddr = 0x00;//*paddr & ~PAMASK;  // port A to inputs
		*pcddr = 0x00;//*pcddr & ~PCMASK;  // port C to inputs
//printf("CLEARED, paddr = 0x%x, pcddr = 0x%x\n", *paddr, *pcddr);
	} else {
		*paddr = 0x0;  // All of port A to inputs
	}

	ctrl = *phdr;
	
	do {
		// step 1, apply RS & WR
		ctrl |= 0x30; // de-assert WR
		ctrl &= ~0x10; // de-assert RS
		*phdr = ctrl;

		// step 2, wait
		i = SETUP;
		COUNTDOWN(i);

		// step 3, assert EN
		ctrl |= 0x8;
		*phdr = ctrl;

		// step 4, wait
		i = PULSE;
		COUNTDOWN(i);

		// step 5, de-assert EN, read result

		if(model == TS7300) {
		  dat = (*padr & PAMASK) | ((*pcdr & PCMASK) << 7);  

//printf("dat = 0x%x, *padr = 0x%x, *pcdr = 0x%x\n", dat, *padr, *pcdr);
		} else {
		  dat = *padr;
		}


		ctrl &= ~0x8; // de-assert EN
		*phdr = ctrl;

		// step 6, wait
		i = HOLD;
		COUNTDOWN(i);
	} while (dat & 0x80 && tries++ < 1000);
	return dat;
}

void command(unsigned int cmd) {
	int i;
	unsigned int ctrl = *phdr;

	if(model == TS7300) {
		*paddr = *paddr | PAMASK; //set port A to outputs
		*pcddr = *pcddr | PCMASK; //set port C to outputs
//printf("SET, *paddr = 0x%x, *pcddr = 0x%x\n", *paddr, *pcddr);
	} else {
		*paddr = 0xff; // set port A to outputs
	}
	
	// step 1, apply RS & WR, send data
	if(model == TS7300) {
//printf("*padr = 0x%x, *pcdr = 0x%x\n", *padr, *pcdr);
		*padr = *padr & ~PAMASK;
		*pcdr = *pcdr & ~PCMASK;
		*padr = (*padr & ~PAMASK) | (cmd & PAMASK);
//if bit 7 of cmd is set the set bit 0 of pcdr
//if bit 7 of cmd is clear then clear bit 0 of pcdr
		*pcdr = *pcdr | (cmd >> 7);
		

//printf("cmd = 0x%x, *padr = 0x%x, *pcdr = 0x%x\n", cmd, *padr, *pcdr);
	} else {
		*padr = cmd;
	}

	ctrl &= ~0x30; // de-assert RS, assert WR
	*phdr = ctrl;

	// step 2, wait
	i = SETUP;
	COUNTDOWN(i);

	// step 3, assert EN
	ctrl |= 0x8;
	*phdr = ctrl;

	// step 4, wait
	i = PULSE;
	COUNTDOWN(i);

	// step 5, de-assert EN	
	ctrl &= ~0x8; // de-assert EN
	*phdr = ctrl;

	// step 6, wait 
	i = HOLD;
	COUNTDOWN(i);
}

void writechars(unsigned char *dat) {
	int i;
	unsigned int ctrl = *phdr;

	do {
		lcdwait();

	if(model == TS7300) {
		*paddr = *paddr | PAMASK; //set port A to outputs
		*pcddr = *pcddr | PCMASK; //set port C to outputs
//printf("SET, *paddr = 0x%x, *pcddr = 0x%x\n", *paddr, *pcddr);
	} else {
		*paddr = 0xff; // set port A to outputs
	}

	// step 1, apply RS & WR, send data
	if(model == TS7300) {

		*padr = *padr & ~PAMASK;
		*pcdr = *pcdr & ~PCMASK;
		*padr = *padr | (*dat & PAMASK);
		*pcdr = *pcdr | ((*dat >> 7) & PCMASK);
//printf("dat = 0x%x, *padr = 0x%x, *pcdr = 0x%x\n", *dat, *padr, *pcdr);
		*dat++;
	} else {
		*padr = *dat++;
	}

		ctrl |= 0x10; // assert RS
		ctrl &= ~0x20; // assert WR
		*phdr = ctrl;

		// step 2
		i = SETUP;
		COUNTDOWN(i);

		// step 3, assert EN
		ctrl |= 0x8;
		*phdr = ctrl;

		// step 4, wait 800 nS
		i = PULSE;
		COUNTDOWN(i);

		// step 5, de-assert EN	
		ctrl &= ~0x8; // de-assert EN
		*phdr = ctrl;

		// step 6, wait
		i = HOLD;
		COUNTDOWN(i);
	} while(*dat);
}