summaryrefslogtreecommitdiff
path: root/drivers/lcd/hd44780.c
blob: c988ebe56c453c23fc0e07c1746093c14ede893b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
/*
Copyright 2022

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "hd44780.h"
#include "gpio.h"
#include "progmem.h"
#include "wait.h"

#ifndef HD44780_DATA_PINS
#    error hd44780: no data pins defined!
#endif

#ifndef HD44780_RS_PIN
#    error hd44780: no RS pin defined!
#endif

#ifndef HD44780_RW_PIN
#    error hd44780: no R/W pin defined!
#endif

#ifndef HD44780_E_PIN
#    error hd44780: no E pin defined!
#endif

static const pin_t data_pins[4] = HD44780_DATA_PINS;

#ifndef HD44780_DISPLAY_COLS
#    define HD44780_DISPLAY_COLS 16
#endif

#ifndef HD44780_DISPLAY_LINES
#    define HD44780_DISPLAY_LINES 2
#endif

#ifndef HD44780_DDRAM_LINE0_ADDR
#    define HD44780_DDRAM_LINE0_ADDR 0x00
#endif
#ifndef HD44780_DDRAM_LINE1_ADDR
#    define HD44780_DDRAM_LINE1_ADDR 0x40
#endif

#define HD44780_INIT_DELAY_MS 16
#define HD44780_ENABLE_DELAY_US 1

static void hd44780_latch(void) {
    writePinHigh(HD44780_E_PIN);
    wait_us(HD44780_ENABLE_DELAY_US);
    writePinLow(HD44780_E_PIN);
}

void hd44780_write(uint8_t data, bool isData) {
    writePin(HD44780_RS_PIN, isData);
    writePinLow(HD44780_RW_PIN);

    for (int i = 0; i < 4; i++) {
        setPinOutput(data_pins[i]);
    }

    // Write high nibble
    for (int i = 0; i < 4; i++) {
        writePin(data_pins[i], (data >> 4) & (1 << i));
    }
    hd44780_latch();

    // Write low nibble
    for (int i = 0; i < 4; i++) {
        writePin(data_pins[i], data & (1 << i));
    }
    hd44780_latch();

    for (int i = 0; i < 4; i++) {
        writePinHigh(data_pins[i]);
    }
}

uint8_t hd44780_read(bool isData) {
    uint8_t data = 0;

    writePin(HD44780_RS_PIN, isData);
    writePinHigh(HD44780_RW_PIN);

    for (int i = 0; i < 4; i++) {
        setPinInput(data_pins[i]);
    }

    writePinHigh(HD44780_E_PIN);
    wait_us(HD44780_ENABLE_DELAY_US);

    // Read high nibble
    for (int i = 0; i < 4; i++) {
        data |= (readPin(data_pins[i]) << i);
    }

    data <<= 4;

    writePinLow(HD44780_E_PIN);
    wait_us(HD44780_ENABLE_DELAY_US);
    writePinHigh(HD44780_E_PIN);
    wait_us(HD44780_ENABLE_DELAY_US);

    // Read low nibble
    for (int i = 0; i < 4; i++) {
        data |= (readPin(data_pins[i]) << i);
    }

    writePinLow(HD44780_E_PIN);

    return data;
}

bool hd44780_busy(void) {
    return hd44780_read(false) & HD44780_BUSY_FLAG;
}

void hd44780_command(uint8_t command) {
    while (hd44780_busy())
        ;
    hd44780_write(command, false);
}

void hd44780_data(uint8_t data) {
    while (hd44780_busy())
        ;
    hd44780_write(data, true);
}

void hd44780_clear(void) {
    hd44780_command(HD44780_CMD_CLEAR_DISPLAY);
}

void hd44780_home(void) {
    hd44780_command(HD44780_CMD_RETURN_HOME);
}

void hd44780_on(bool cursor, bool blink) {
    if (cursor) {
        if (blink) {
            hd44780_command(HD44780_CMD_DISPLAY | HD44780_DISPLAY_ON | HD44780_DISPLAY_CURSOR | HD44780_DISPLAY_BLINK);
        } else {
            hd44780_command(HD44780_CMD_DISPLAY | HD44780_DISPLAY_ON | HD44780_DISPLAY_CURSOR);
        }
    } else {
        hd44780_command(HD44780_CMD_DISPLAY | HD44780_DISPLAY_ON);
    }
}

void hd44780_off() {
    hd44780_command(HD44780_CMD_DISPLAY);
}

void hd44780_set_cgram_address(uint8_t address) {
    hd44780_command(HD44780_CMD_SET_CGRAM_ADDRESS + (address & 0x3F));
}

void hd44780_set_ddram_address(uint8_t address) {
    hd44780_command(HD44780_CMD_SET_DDRAM_ADDRESS + (address & 0x7F));
}

void hd44780_init(bool cursor, bool blink) {
    setPinOutput(HD44780_RS_PIN);
    setPinOutput(HD44780_RW_PIN);
    setPinOutput(HD44780_E_PIN);

    for (int i = 0; i < 4; i++) {
        setPinOutput(data_pins[i]);
    }

    wait_ms(HD44780_INIT_DELAY_MS);

    // Manually configure for 4-bit mode - can't use hd44780_command() yet
    // HD44780U datasheet, Fig. 24 (p46)
    writePinHigh(data_pins[0]); // Function set
    writePinHigh(data_pins[1]); // DL = 1
    hd44780_latch();
    wait_ms(5);
    // Send again
    hd44780_latch();
    wait_us(64);
    // And again (?)
    hd44780_latch();
    wait_us(64);

    writePinLow(data_pins[0]); // DL = 0
    hd44780_latch();
    wait_us(64);

#if HD44780_DISPLAY_LINES == 1
    hd44780_command(HD44780_CMD_FUNCTION); // 4 bit, 1 line, 5x8 dots
#else
    hd44780_command(HD44780_CMD_FUNCTION | HD44780_FUNCTION_2_LINES); // 4 bit, 2 lines, 5x8 dots
#endif
    hd44780_on(cursor, blink);
    hd44780_clear();
    hd44780_home();
    hd44780_command(HD44780_CMD_ENTRY_MODE | HD44780_ENTRY_MODE_INC);
}

void hd44780_set_cursor(uint8_t col, uint8_t line) {
    register uint8_t address = col;

#if HD44780_DISPLAY_LINES == 1
    address += HD44780_DDRAM_LINE0_ADDR;
#elif HD44780_DISPLAY_LINES == 2
    if (line == 0) {
        address += HD44780_DDRAM_LINE0_ADDR;
    } else {
        address += HD44780_DDRAM_LINE1_ADDR;
    }
#endif

    hd44780_set_ddram_address(address);
}

void hd44780_define_char(uint8_t index, uint8_t *data) {
    hd44780_set_cgram_address((index & 0x7) << 3);
    for (uint8_t i = 0; i < 8; i++) {
        hd44780_data(data[i]);
    }
}

void hd44780_putc(char c) {
    while (hd44780_busy())
        ;
    uint8_t current_position = hd44780_read(false);

    if (c == '\n') {
        hd44780_set_cursor(0, current_position < HD44780_DDRAM_LINE1_ADDR ? 1 : 0);
    } else {
#if defined(HD44780_WRAP_LINES)
#    if HD44780_DISPLAY_LINES == 1
        if (current_position == HD44780_DDRAM_LINE0_ADDR + HD44780_DISPLAY_COLS) {
            // Go to start of line
            hd44780_set_cursor(0, 0);
        }
#    elif HD44780_DISPLAY_LINES == 2
        if (current_position == HD44780_DDRAM_LINE0_ADDR + HD44780_DISPLAY_COLS) {
            // Go to start of second line
            hd44780_set_cursor(0, 1);
        } else if (current_position == HD44780_DDRAM_LINE1_ADDR + HD44780_DISPLAY_COLS) {
            // Go to start of first line
            hd44780_set_cursor(0, 0);
        }
#    endif
#endif
        hd44780_data(c);
    }
}

void hd44780_puts(const char *s) {
    register char c;
    while ((c = *s++)) {
        hd44780_putc(c);
    }
}

#if defined(__AVR__)
void hd44780_define_char_P(uint8_t index, const uint8_t *data) {
    hd44780_set_cgram_address(index << 3);
    for (uint8_t i = 0; i < 8; i++) {
        hd44780_data(pgm_read_byte(data++));
    }
}

void hd44780_puts_P(const char *s) {
    register char c;
    while ((c = pgm_read_byte(s++))) {
        hd44780_putc(c);
    }
}
#endif