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-rw-r--r--drivers/lcd/hd44780.c284
1 files changed, 284 insertions, 0 deletions
diff --git a/drivers/lcd/hd44780.c b/drivers/lcd/hd44780.c
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--- /dev/null
+++ b/drivers/lcd/hd44780.c
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+/*
+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