/*
* i2c driver module for Hitachi HD44780 based LCD displays.
* The LCD is operated in it's 4 bit-mode to be connected to the 8 bit-port
* of a single PCF8574(A) or PCA9554(A) that is accessed by the server via the i2c bus.
*
* Copyright (c) 2005 Matthias Goebl <matthias.goebl@goebl.net>
* 2000, 1999, 1995 Benjamin Tse <blt@Comports.com>
* 2001 Joris Robijn <joris@robijn.net>
* 1999 Andrew McMeikan <andrewm@engineer.com>
* 1998 Richard Rognlie <rrognlie@gamerz.net>
* 1997 Matthias Prinke <m.prinke@trashcan.mcnet.de>
*
* The connections are:
* PCF8574AP LCD
* P0 (4) D4 (11)
* P1 (5) D5 (12)
* P2 (6) D6 (13)
* P3 (7) D7 (14)
* P4 (9) RS (4)
* P5 (10) RW (5)
* P6 (11) EN (6)
*
* Backlight
* P7 (12) /backlight (optional, active-low)
*
* Configuration:
* device=/dev/i2c-0 # the device file of the i2c bus
* port=0x20 # the i2c address of the i2c port expander
*
* Attention: Bit 8 of the address given in port is special:
* It tells the driver to treat the device as PCA9554 or similar,
* a device that needs a 2-byte command, and it will be stripped
* off the address.
* So we have:
* port=0x20..0x27 PCF8574 with A[012]=0..7
* port=0x38..0x3f PCF8574A with A[012]=0..7
* port=0xa0..0xa7 PCA9554 with A[012]=0..7
* port=0xa0..0xa7 PCA9554A with A[012]=0..7
*
* When using this driver, DON'T load the i2c chip module (e.g. pcf8574),
* you only need the i2c bus driver module!
*
*
* Based mostly on the hd44780-4bit module, see there for a complete history.
* Suggestions for PCA9554 support from Tonu Samuel <tonu@jes.ee>.
*
* This file is released under the GNU General Public License. Refer to the
* COPYING file distributed with this package.
*/
#include "hd44780-i2c.h"
#include "hd44780-low.h"
#include "shared/str.h"
#include "shared/report.h"
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <linux/i2c-dev.h>
/* I2C_SLAVE is missing in linux/i2c-dev.h from kernel headers of 2.4.x kernels */
#ifndef I2C_SLAVE
#define I2C_SLAVE 0x0703 /* Change slave address */
#endif
// Generally, any function that accesses the LCD control lines needs to be
// implemented separately for each HW design. This is typically (but not
// restricted to):
// HD44780_senddata
// HD44780_readkeypad
void i2c_HD44780_senddata(PrivateData *p, unsigned char displayID, unsigned char flags, unsigned char ch);
void i2c_HD44780_backlight(PrivateData *p, unsigned char state);
#define RS 0x10
#define RW 0x20
#define EN 0x40
#define BL 0x80
// note that the above bits are all meant for the data port of PCF8574
#define I2C_ADDR_MASK 0x7f
#define I2C_PCAX_MASK 0x80
static void
i2c_out(PrivateData *p, unsigned char val)
{
__u8 data[2];
int datalen;
static int no_more_errormsgs=0;
if (p->port & I2C_PCAX_MASK) { // we have a PCA9554 or similar, that needs a 2-byte command
data[0]=1; // command: read/write output port register
data[1]=val;
datalen=2;
} else { // we have a PCF8574 or similar, that needs a 1-byte command
data[0]=val;
datalen=1;
}
if (write(p->fd,data,datalen) != datalen) {
report(no_more_errormsgs?RPT_DEBUG:RPT_ERR, "HD44780: I2C: i2c write data %u to address %u failed: %s",
val, p->port & I2C_ADDR_MASK, strerror(errno));
no_more_errormsgs=1;
}
}
#define DEFAULT_DEVICE "/dev/i2c-0"
// initialisation function
int
hd_init_i2c(Driver *drvthis)
{
PrivateData *p = (PrivateData*) drvthis->private_data;
HD44780_functions *hd44780_functions = p->hd44780_functions;
int enableLines = EN;
char device[256] = DEFAULT_DEVICE;
p->backlight_bit = BL;
/* READ CONFIG FILE */
/* Get serial device to use */
strncpy(device, drvthis->config_get_string(drvthis->name, "Device", 0, DEFAULT_DEVICE), sizeof(device));
device[sizeof(device)-1] = '\0';
report(RPT_INFO,"HD44780: I2C: Using device '%s' and address %u for a %s",
device, (p->port & I2C_ADDR_MASK) ? "PCA9554(A)" : "PCF8574(A)");
// Open the I2C device
p->fd = open(device, O_RDWR);
if (p->fd < 0) {
report(RPT_ERR, "HD44780: I2C: open i2c device '%s' failed: %s", device, strerror(errno));
return(-1);
}
// Set I2C address
if (ioctl(p->fd,I2C_SLAVE, p->port & I2C_ADDR_MASK) < 0) {
report(RPT_ERR, "HD44780: I2C: set address to '%i': %s", p->port & I2C_ADDR_MASK, strerror(errno));
return(-1);
}
if (p->port & I2C_PCAX_MASK) { // we have a PCA9554 or similar, that needs special config
__u8 data[2];
data[0] = 2; // command: set polarity inversion
data[1] = 0; // -> no polarity inversion
if (write(p->fd,data,2) != 2) {
report(RPT_ERR, "HD44780: I2C: i2c set polarity inversion failed: %s", strerror(errno));
}
data[0] = 3; // command: set output direction
data[1] = 0; // -> all pins are outputs
if (write(p->fd,data,2) != 2) {
report(RPT_ERR, "HD44780: I2C: i2c set output direction failed: %s", strerror(errno));
}
}
hd44780_functions->senddata = i2c_HD44780_senddata;
hd44780_functions->backlight = i2c_HD44780_backlight;
hd44780_functions->scankeypad = NULL;
// powerup the lcd now
/* We'll now send 0x03 a couple of times,
* which is in fact (FUNCSET | IF_8BIT) >> 4 */
i2c_out(p, 0x03);
if (p->delayBus)
hd44780_functions->uPause(p, 1);
i2c_out(p, enableLines | 0x03);
if (p->delayBus)
hd44780_functions->uPause(p, 1);
i2c_out(p, 0x03);
hd44780_functions->uPause(p, 15000);
i2c_out(p, enableLines | 0x03);
if (p->delayBus)
hd44780_functions->uPause(p, 1);
i2c_out(p, 0x03);
hd44780_functions->uPause(p, 5000);
i2c_out(p, enableLines | 0x03);
if (p->delayBus)
hd44780_functions->uPause(p, 1);
i2c_out(p, 0x03);
hd44780_functions->uPause(p, 100);
i2c_out(p, enableLines | 0x03);
if (p->delayBus)
hd44780_functions->uPause(p, 1);
i2c_out(p, 0x03);
hd44780_functions->uPause(p, 100);
// now in 8-bit mode... set 4-bit mode
i2c_out(p, 0x02);
if (p->delayBus)
hd44780_functions->uPause(p, 1);
i2c_out(p, enableLines | 0x02);
if (p->delayBus)
hd44780_functions->uPause(p, 1);
i2c_out(p, 0x02);
hd44780_functions->uPause(p, 100);
// Set up two-line, small character (5x8) mode
hd44780_functions->senddata(p, 0, RS_INSTR, FUNCSET | IF_4BIT | TWOLINE | SMALLCHAR);
hd44780_functions->uPause(p, 40);
common_init(p, IF_4BIT);
return 0;
}
// i2c_HD44780_senddata
void
i2c_HD44780_senddata(PrivateData *p, unsigned char displayID, unsigned char flags, unsigned char ch)
{
unsigned char enableLines = 0, portControl = 0;
unsigned char h = (ch >> 4) & 0x0f; // high and low nibbles
unsigned char l = ch & 0x0f;
if (flags == RS_INSTR)
portControl = 0;
else //if (flags == RS_DATA)
portControl = RS;
portControl |= p->backlight_bit;
enableLines = EN;
i2c_out(p, portControl | h);
if (p->delayBus)
p->hd44780_functions->uPause(p, 1);
i2c_out(p, enableLines | portControl | h);
if (p->delayBus)
p->hd44780_functions->uPause(p, 1);
i2c_out(p, portControl | h);
i2c_out(p, portControl | l);
if (p->delayBus)
p->hd44780_functions->uPause(p, 1);
i2c_out(p, enableLines | portControl | l);
if (p->delayBus)
p->hd44780_functions->uPause(p, 1);
i2c_out(p, portControl | l);
}
void i2c_HD44780_backlight(PrivateData *p, unsigned char state)
{
p->backlight_bit = ((!p->have_backlight||state) ? 0 : BL);
i2c_out(p, p->backlight_bit);
}
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