mirror of
https://github.com/co-dan/ocaml-wiringpi/
synced 2025-10-30 20:43:52 +01:00
140 lines
4.0 KiB
OCaml
140 lines
4.0 KiB
OCaml
(** An example with Adafruit character LCD, HD44780. *)
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open Gpio3
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(** Parameters *)
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type mono_lcd = {
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columns: int;
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rows: int;
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rs: pin;
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en: pin;
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d4: pin;
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d5: pin;
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d6: pin;
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d7: pin
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}
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let lcd = {
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columns = 16;
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rows = 2;
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rs = GPIO20;
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en = GPIO16;
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d4 = GPIO19;
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d5 = GPIO5;
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d6 = GPIO11;
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d7 = GPIO10;
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}
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(** MAGIC NUMBERS *)
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(* Commands *)
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let _lcd_cleardisplay = (0x01)
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let _lcd_returnhome = (0x02)
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let _lcd_entrymodeset = (0x04)
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let _lcd_displaycontrol = (0x08)
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let _lcd_cursorshift = (0x10)
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let _lcd_functionset = (0x20)
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let _lcd_setcgramaddr = (0x40)
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let _lcd_setddramaddr = (0x80)
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(* Entry flags *)
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let _lcd_entryleft = (0x02)
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let _lcd_entryshiftdecrement = (0x00)
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(* Control flags *)
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let _lcd_displayon = (0x04)
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let _lcd_cursoron = (0x02)
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let _lcd_cursoroff = (0x00)
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let _lcd_blinkon = (0x01)
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let _lcd_blinkoff = (0x00)
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(* Move flags *)
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let _lcd_displaymove = (0x08)
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let _lcd_moveright = (0x04)
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let _lcd_moveleft = (0x00)
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(* Function set flags *)
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let _lcd_4bitmode = (0x00)
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let _lcd_2line = (0x08)
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let _lcd_1line = (0x00)
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let _lcd_5x8dots = (0x00)
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(* Offset for up to 4 rows. *)
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let _lcd_row_offsets = [|0x00; 0x40; 0x14; 0x54|]
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let pulse_enable lcd =
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digital_write lcd.en LOW;
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(* 1 microsec pause *)
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Unix.sleepf(0.0000001);
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digital_write lcd.en HIGH;
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Unix.sleepf(0.0000001);
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digital_write lcd.en LOW;
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Unix.sleepf(0.00001)
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(** write 8 bits of data *)
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let write8 lcd ?(char_mode=false) value =
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(* one ms delay to prevent writing too quickly *)
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Unix.sleepf(0.001);
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let char_mode_value = if char_mode then HIGH else LOW in
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digital_write lcd.rs char_mode_value;
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let val_of_int i = if i > 0 then HIGH else LOW in
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let ival = Char.code value in
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(* write the UPPER 4 bits (in reverse order) *)
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digital_write lcd.d4 (val_of_int ((ival lsr 4) land 1));
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digital_write lcd.d5 (val_of_int ((ival lsr 5) land 1));
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digital_write lcd.d6 (val_of_int ((ival lsr 6) land 1));
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digital_write lcd.d7 (val_of_int ((ival lsr 7) land 1));
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pulse_enable lcd;
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(* write the LOWER 4 bits *)
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digital_write lcd.d4 (val_of_int (ival land 1));
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digital_write lcd.d5 (val_of_int ((ival lsr 1) land 1));
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digital_write lcd.d6 (val_of_int ((ival lsr 2) land 1));
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digital_write lcd.d7 (val_of_int ((ival lsr 3) land 1));
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pulse_enable lcd
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(** same as [write8] but write an int (must be within the range) *)
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let write8_unsafe lcd ?(char_mode=false) ival =
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write8 lcd ~char_mode (Char.unsafe_chr ival)
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let setup lcd =
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Gpio3.setup ();
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pin_mode lcd.rs OUT;
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pin_mode lcd.en OUT;
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pin_mode lcd.d4 OUT;
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pin_mode lcd.d5 OUT;
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pin_mode lcd.d6 OUT;
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pin_mode lcd.d7 OUT;
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(* MAGIC *)
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write8_unsafe lcd 0x33;
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write8_unsafe lcd 0x32;
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(* set up some stuff *)
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let displayctrl = _lcd_displayon lor _lcd_cursoroff lor _lcd_blinkoff in
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let displayfn = _lcd_4bitmode lor _lcd_1line lor _lcd_2line lor _lcd_5x8dots in
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let displaymode = _lcd_entryleft lor _lcd_entryshiftdecrement in
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write8_unsafe lcd (displayctrl lor _lcd_displaycontrol);
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write8_unsafe lcd (displayfn lor _lcd_functionset);
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write8_unsafe lcd (displaymode lor _lcd_entrymodeset);
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Unix.sleepf(0.003)
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let clear lcd =
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write8_unsafe lcd _lcd_cleardisplay;
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Unix.sleepf(0.003)
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let shift_left lcd =
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write8_unsafe lcd (_lcd_cursorshift lor _lcd_displaymove lor _lcd_moveleft)
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let shift_right lcd =
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write8_unsafe lcd (_lcd_cursorshift lor _lcd_displaymove lor _lcd_moveright)
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let set_position lcd x y =
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let c = x mod lcd.columns in
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let r = y mod lcd.rows in
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if (c < 0 || r < 0) then failwith "Lcd.set_position: Negative row or column";
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write8_unsafe lcd (_lcd_setddramaddr lor (c + _lcd_row_offsets.(r)))
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let write_bytes lcd bts =
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Bytes.iter (fun c -> write8 lcd c ~char_mode:true) bts
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let _ =
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setup lcd;
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clear lcd;
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set_position lcd 0 0;
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write_bytes lcd (Bytes.of_string "Hello, world.")
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