Re: [Lcd4linux-devel] HD44780 changes

[Luis C. <lfc...@lf...>]

Luis.F.Correia wrote:

>Hi List, especially Luis,
>
>I just checked in a new version of drv_HD44780.c. I did some code 
>cleanups, and separated the parport specific stuff from the display 
>specific stuff, and already wrote a framework for other 'busses'. There 
>is support for a keyword 'bus' in the display section of lcd4linux.conf, 
>which can be 'parport (default) or 'i2c'. There are already skeleton 
>functions for I2C access.
>
>So Luis can start filling these skeletion functions!
>
>But take care, I'm currently working on the HD44780 driver, too! So 
>update regularly!
>
>The reason on my side is that I got a Nexcom 19" blade server donated by 
>OpenSystems, which has a 16x2 display, and four keys.
>
>Yes, keys! I'm working on keypad support for lcd4linux.
>
>stay tuned!
>
>  
>
Ok, here it goes my first try to support I2C:
This is a huge mess, because i'm working on a CVS version of some weeks ago.
Since the functions were empty, I think i'm not stepping on anyone's toes.

This reads the following config variables:
    Port '/dev/i2c-0'
    Device '70'

and my config file looks like this:

Display HD44780-I2C {
    Driver 'HD44780'
    Model 'WRAP1C-PCF8574'
    Port '/dev/i2c-0'
    Device '70'
    Bus 'i2c'
    Bits '4'
    Size '20x4'
    asc255bug 0
    Icons 1
    Wire {
        RW     'DB5'
        RS     'DB4'
        ENABLE 'DB6'
        GPO    'GND'
    }
}


-------------------------------------
includes at the top of the file:
#include <linux/i2c.h>
#include <linux/i2c-dev.h>

global variable:
/* handle for I2C device*/
static int i2c_device;

Functions:

/****************************************/
/***  i2c dependant functions         ***/
/****************************************/


static void drv_HD_I2C_nibble (const unsigned char controller, const 
unsigned char nibble)
{
  /* clear ENABLE */
  /* put data on DB1..DB4 */
  /* nibble already contains RS bit! */
  i2c_smbus_write_byte_data(i2c_device, 0, nibble);

  /* Address set-up time */
  ndelay(T_AS);
 
  /* rise ENABLE */
  i2c_smbus_write_byte_data(i2c_device, 0, nibble | SIGNAL_ENABLE);
 
  /* Enable pulse width */
  ndelay(T_PW);

  /* lower ENABLE */
  i2c_smbus_write_byte_data(i2c_device, 0, nibble);

  /* Address hold time */
  ndelay(T_H);

}

static void drv_HD_I2C_byte (const unsigned char controller, const 
unsigned char data)
{
  /* send data with RS disabled */
  /* send high nibble of the data */
  drv_HD_I2C_nibble (controller, ((data>>4)&0x0f)|SIGNAL_RS);

  /* Make sure we honour T_CYCLE */
  ndelay(T_CYCLE-T_AS-T_PW);

  /* send low nibble of the data */
  drv_HD_I2C_nibble(controller, (data&0x0f)|SIGNAL_RS);
}

static void drv_HD_I2C_command (const unsigned char controller, const 
unsigned char cmd, const int delay)
{
  /* send data with RS disabled */
  drv_HD_I2C_byte (controller, cmd);
 
  /* wait for command completion */
  udelay(delay);
}

static void drv_HD_I2C_data (const unsigned char controller, const char 
*string, const int len, const int delay)
{
  int l = len;
 
  /* sanity check */
  if (len<=0) return;
 
  while (l--) {
    /* send data with RS enabled */
    drv_HD_I2C_byte (controller, *(string++));
     
    /* wait for command completion */
    udelay(delay);
  }
}

static int drv_HD_I2C_load (const char *section)
{
    int dev;
    char *bus,*device;

    bus    =cfg_get(section, "Port", NULL);   
    device =cfg_get(section, "Device", NULL);   
    dev    =0x70;

    info("%s: initializing I2C bus %s",Name,bus);
    if ((i2c_device = open(bus,O_RDWR)) < 0)
    {
      error("%s: I2C bus %s open failed !\n",Name,bus);
      return -1;
    }

    info("%s: initializing I2C slave device 0x%x",Name,dev);
    if (ioctl(i2c_device,I2C_SLAVE, (dev>>1) ) < 0)
    {
        error("%s: error initializing device 0x%x\n",Name,dev);
        close(i2c_device);
        return -1;
    }

    info("%s: detecting I2C device 0x%x on bus %s ",Name,dev,bus);
    if (i2c_smbus_write_quick(i2c_device,I2C_SMBUS_WRITE) < 0)
    {
        error("%s: i2c slave-device 0x%x not found!\n",Name,dev);
        close(i2c_device);
        return -1;
    }

    if (cfg_number(section, "Bits", 8, 4, 8, &Bits)<0) return -1;
    if (Bits!=4) {
    error ("%s: bad %s.Bits '%d' from %s, should be '4' ", Name, 
section, Bits, cfg_source());
    return -1;
    }   
 
    info ("%s: using %d bit mode", Name, Bits);
 
  /* initialize *both* displays */
    drv_HD_I2C_nibble  (allControllers, 0x03); udelay(T_INIT1); /* 4 Bit 
mode, wait 4.1 ms */
    drv_HD_I2C_nibble  (allControllers, 0x03); udelay(T_INIT2); /* 4 Bit 
mode, wait 100 us */
    drv_HD_I2C_nibble  (allControllers, 0x03); udelay(T_INIT1); /* 4 Bit 
mode, wait 4.1 ms */
    drv_HD_I2C_nibble  (allControllers, 0x02); udelay(T_INIT2); /* 4 Bit 
mode, wait 100 us */
    drv_HD_I2C_command (allControllers, 0x28, T_EXEC);           /* 4 
Bit mode, 1/16 duty cycle, 5x8 font */

    info("%s: I2C initialization done", Name);

  return 0;
}


static void drv_HD_I2C_stop (void)
{
  /* clear all signals */
  // drv_generic_i2c_data (0);
  /* close port */
  // drv_generic_i2c_close();

    close(i2c_device);
}
-------------------------------------

Michael, please feel free to redirect that SCUD missile you have to my 
email address :)

Cheers!

Luis Correia