Synopsis

typedef struct {
  int (*capabilities)(HD44780_DRIVER_t *);
  void (*set_e)(HD44780_DRIVER_t *, int);
  void (*set_rw)(HD44780_DRIVER_t *, int);
  void (*set_rs)(HD44780_DRIVER_t *, int);
  void (*set_dbus)(HD44780_DRIVER_t *, int);
  void (*set_backlight)(HD44780_DRIVER_t *, int);
  int (*read_dbus)(HD44780_DRIVER_t *);
  void *extra;
  int x;
  int y;
  int cursor;
  int width;
  int height;
  char lcd[];
} HD44780_DRIVER_t;

Description

HD44780_DRIVER_t contains a set of methods that the high-level driver uses to implement the physical layer of the display.

Structure

capabilities

Returns the underlying capabilities of the physical interface. The method should return the bitwise-or of the flags HD44780_BIDIRECTIONAL_DBUS and HD44780_4BIT_INTERFACE. If the data bus is bidirectional then the high-level driver will try to read the bus using read_dbus (to establish LCD readiness) and set its control its direction using set_dbus_input and set_dbus_output. Returning HD44780_4BIT_INTERFACE indicates that the data bus bus is physically connected using only four bits and the physical-layer driver adapts to 4-bit mode.

set_e

Sets the E signal high when state is non-zero and low when state is zero.

set_rw

Sets the R/W signal high when state is non-zero and low when state is zero.

set_rs

Sets the RS signal high when state is non-zero and low when state is zero.

set_dbus

Sets the data bus to output mode and its outputs to state. For a 4-bit data bus, state will contain valid data in bits 4 through 7 with all other bits zero, and for an 8-bit data bus, state will contain valid data in bits 0 through 7.

set_backlight

Sets the display backlight level to level. This is a driver-specific function that is provided as a convenience in order to enable clients to turn the backlight on and off, or to set its level using PWM.

read_dbus

Sets the data bus to input mode, reads the data bus, and returns what is read. For a 4-bit data bus, the four data bits are expected in bits 4 through 7 and for an 8-bit data bus they are expected in bits 0 through 7.