Introduction

This wiki page describes the Hardware Abstraction Layer (HAL) for Ucglib

Details

The hardware abtraction layer is implemented as callback function. The callback function receives several messages. The following code can be used as a template:

int16_t ucg_com_my_own_hal(ucg_t *ucg, int16_t msg, uint16_t arg, uint8_t *data)
{

  switch(msg)
  {
    case UCG_COM_MSG_POWER_UP:
      /* "data" is a pointer to ucg_com_info_t structure with the following information: */
      /*	((ucg_com_info_t *)data)->serial_clk_speed value in nanoseconds */
      /*	((ucg_com_info_t *)data)->parallel_clk_speed value in nanoseconds */
      /* "arg" is not used */

      /* This message is sent once at the uC startup and for power up. */
      /* setup i/o or do any other setup */
      break;

    case UCG_COM_MSG_POWER_DOWN:
      /* "data" and "arg" are not used*/
      /* This message is sent for a power down request */

      break;
    case UCG_COM_MSG_DELAY:
      /* "data" is not used */
      /* "arg" contains the number of microseconds for the delay */
      /* By receiving this message, the following code should delay by */
      /* "arg" microseconds. One microsecond is 0.000001 second */

      break;
    case UCG_COM_MSG_CHANGE_RESET_LINE:
      /* "data" is not used */
      /* "arg" = 1: set the reset output line to 1 */
      /* "arg" = 0: set the reset output line to 0 */

      break;
    case UCG_COM_MSG_CHANGE_CD_LINE:
      /* "ucg->com_status"  bit 0 contains the old level for the CD line */
      /* "data" is not used */
      /* "arg" = 1: set the command/data (a0) output line to 1 */
      /* "arg" = 0: set the command/data (a0) output line to 0 */

      break;
    case UCG_COM_MSG_CHANGE_CS_LINE:
      /* "ucg->com_status"  bit 1 contains the old level for the CS line */
      /* "data" is not used */
      /* "arg" = 1: set the chipselect output line to 1 */
      /* "arg" = 0: set the chipselect output line to 0 */

      break;
    case UCG_COM_MSG_SEND_BYTE:
      /* "data" is not used */
      /* "arg" contains one byte, which should be sent to the display */
      /* The current status of the CD line is available */
      /* in bit 0 of u8g->com_status */

      break;
    case UCG_COM_MSG_REPEAT_1_BYTE:
      /* "data[0]" contains one byte */
      /* repeat sending the byte in data[0] "arg" times */
      /* The current status of the CD line is available */
      /* in bit 0 of u8g->com_status */

      break;
    case UCG_COM_MSG_REPEAT_2_BYTES:
      /* "data[0]" contains first byte */
      /* "data[1]" contains second byte */
      /* repeat sending the two bytes "arg" times */
      /* The current status of the CD line is available */
      /* in bit 0 of u8g->com_status */

      break;
    case UCG_COM_MSG_REPEAT_3_BYTES:
      /* "data[0]" contains first byte */
      /* "data[1]" contains second byte */
      /* "data[2]" contains third byte */
      /* repeat sending the three bytes "arg" times */
      /* The current status of the CD line is available */
      /* in bit 0 of u8g->com_status */

      break;
    case UCG_COM_MSG_SEND_STR:
      /* "data" is an array with "arg" bytes */
      /* send "arg" bytes to the display */

      break;
    case UCG_COM_MSG_SEND_CD_DATA_SEQUENCE:
      /* "data" is a pointer to two bytes, which contain the cd line */
      /* status and display data */
      /* "arg" contains the number of these two byte tuples which need to */
      /* be analysed and sent. Bellow is a example sequence */
      /* The content of bit 0 in u8g->com_status is undefined for this message */

      while(arg > 0)
      {
	if ( *data != 0 )
	{
	  if ( *data == 1 )
	  {
            /* set CD (=D/C=A0) line to low */
	  }
	  else
	  {
            /* set CD (=D/C=A0) line to high */
	  }
	}
	data++;
        /* send *data to the display */
	data++;
	arg--;
      }
      break;
  }
  return 1;
}

To setup the library, use the following init procedure:

ucg_int_t ucg_Init(ucg_t *ucg, ucg_dev_fnptr device_cb, ucg_dev_fnptr ext_cb, ucg_com_fnptr com_cb);

The above mentioned HAL-callback is the last argument for this procedure:

/* create memory area for ucglib variables */
ucg_t ucg;

/* setup ucglib, see ucg.h for a list of ucg_dev and ucg_ext objects */
ucg_Init(&ucg, ucg_dev_ssd1351_18x128x128_ilsoft, ucg_ext_ssd1351_18, ucg_com_my_own_hal);

/* define prefered font rendering method (no text will be visibile, if this is missing */
ucg_SetFontMode(&ucg, UCG_FONT_MODE_TRANSPARENT);