diff options
Diffstat (limited to 'drivers/lcd/hd44780.c')
| -rw-r--r-- | drivers/lcd/hd44780.c | 284 |
1 files changed, 284 insertions, 0 deletions
diff --git a/drivers/lcd/hd44780.c b/drivers/lcd/hd44780.c new file mode 100644 index 0000000000..c988ebe56c --- /dev/null +++ b/drivers/lcd/hd44780.c @@ -0,0 +1,284 @@ +/* +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 |