Russian text on display with HD44780 controller and Japanese character generator
Non-standard way of controlling the display on the HD44780 controller for drawing Russian fonts with any custom display code table.
The very idea of such a control was born from the task of Russifying a device with a custom display based on the HD44780 controller. Having considered the option of replacing Russian characters with Latin characters similar in designation, I decided not to get involved with this, because it looks like a rough, but a commercial device.
Unlike OLED displays based on the Winstar WS0010 driver, the displays on the HD44780 drivers or their analogs do not have a graphical mode of operation. But they have a so-called CGRAM memory, in which you can write up to 8 characters in a graphical representation.
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The algorithm itself works out pretty simple:
In this case, it is very important to properly configure the display control, and use close to the minimum exchange timings, as well as, if possible, an 8-bit interface to the display (although according to tests, the 4-bit interface does not load the controller too much). You must also use the read signal BUSY on line D7 from the display, to reduce the waiting time for its reaction.
How it looks on a real display can be viewed on the video below:
The top line is controlled by a quick redraw and displays information from CGRAM. The line contains graphically drawn characters from the code table CP866 with codes 0x80-0xFF, the pseudografics are replaced with chess diamonds. In the bottom line there are symbols of the built-in character generator of the display and a number of their codes.
The disadvantages of the method:
When the update frequency is below 25Hz, flickering is noticeable when viewed at an angle, while looking straight up it is not visible vertically.
Also slightly decreases the contrast of the image from the display, but it is almost not noticeable.
The very idea of such a control was born from the task of Russifying a device with a custom display based on the HD44780 controller. Having considered the option of replacing Russian characters with Latin characters similar in designation, I decided not to get involved with this, because it looks like a rough, but a commercial device.
Unlike OLED displays based on the Winstar WS0010 driver, the displays on the HD44780 drivers or their analogs do not have a graphical mode of operation. But they have a so-called CGRAM memory, in which you can write up to 8 characters in a graphical representation.
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The algorithm itself works out pretty simple:
- We start the timer of drawing on the frequency of interruptions acceptable on loading on the processor.
- In the timer interrupt:
- we erase (we fill with gaps) everything that was on the display;
- load the required graphic information into the first 8 familiarity CGRAM memory of the controller;
- We display these characters on the display at a given offset and exit the interrupt.
The code looks like this:
// Cham map 0x80 - 0xFF, with filler uint8_t cmap[] = { 0x04, 0x0a, 0x11, 0x11, 0x1f, 0x11, 0x11, 0x00, // russian A 0x1f, 0x10, 0x10, 0x1e, 0x11, 0x11, 0x1e, 0x00, // russian Be 0x1e, 0x11, 0x11, 0x1e, 0x11, 0x11, 0x1e, 0x0, // russian Ve 0x1f, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x00, // russian Ge 0x0e, 0x0a, 0x0a, 0x0a, 0x0a, 0x1f, 0x11, 0x00, // russian De 0x1f, 0x10, 0x10, 0x1e, 0x10, 0x10, 0x1f, 0x00, // russian E 0x15, 0x15, 0x15, 0x0e, 0x15, 0x15, 0x15, 0x00, // russian Zhe 0x0e, 0x11, 0x01, 0x06, 0x01, 0x11, 0x0e, 0x00, // russian Ze 0x11, 0x11, 0x11, 0x13, 0x15, 0x19, 0x11, 0x00, // russian I 0x0e, 0x00, 0x11, 0x13, 0x15, 0x19, 0x11, 0x00, // russian Ij 0x11, 0x12, 0x14, 0x18, 0x14, 0x12, 0x11, 0x00, // russian Ka 0x07, 0x09, 0x09, 0x09, 0x09, 0x09, 0x11, 0x00, // russian L 0x11, 0x11, 0x1b, 0x15, 0x15, 0x11, 0x11, 0x00, // russian M 0x11, 0x11, 0x11, 0x1f, 0x11, 0x11, 0x11, 0x00, // russian N 0x0e, 0x11, 0x11, 0x11, 0x11, 0x11, 0x0e, 0x00, // russian O 0x1f, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x00, // russian Pe 0x1e, 0x11, 0x11, 0x11, 0x1e, 0x10, 0x10, 0x00, // russian Re 0x0e, 0x11, 0x10, 0x10, 0x10, 0x11, 0x0e, 0x00, // russian Se 0x1f, 0x04, 0x04, 0x04, 0x04, 0x04, 0x04, 0x00, // russian Te 0x11, 0x11, 0x11, 0x0f, 0x01, 0x11, 0x0e, 0x00, // russian U 0x0e, 0x15, 0x15, 0x15, 0x0e, 0x04, 0x04, 0x00, // russian Fe 0x11, 0x0a, 0x04, 0x04, 0x0a, 0x0a, 0x11, 0x00, // russian He 0x12, 0x12, 0x12, 0x12, 0x12, 0x1f, 0x01, 0x00, // russian Ce 0x11, 0x11, 0x11, 0x0f, 0x01, 0x01, 0x01, 0x00, // russian Che 0x11, 0x15, 0x15, 0x15, 0x15, 0x15, 0x1f, 0x00, // russian She 0x11, 0x15, 0x15, 0x15, 0x15, 0x1f, 0x01, 0x00, // russian Sche 0x18, 0x08, 0x08, 0x0e, 0x09, 0x09, 0x0e, 0x00, // russian Tverduy znak 0x11, 0x11, 0x19, 0x15, 0x15, 0x15, 0x19, 0x00, // russian bI 0x10, 0x10, 0x1e, 0x11, 0x11, 0x11, 0x1e, 0x00, // russian Myagkiy znak 0x1e, 0x01, 0x01, 0x0f, 0x01, 0x01, 0x1e, 0x00, // russian Ee 0x17, 0x15, 0x15, 0x1d, 0x15, 0x15, 0x17, 0x00, // russian You 0x0f, 0x11, 0x11, 0x0f, 0x05, 0x09, 0x11, 0x00, // russian Ya // 0x00, 0x00, 0x0e, 0x01, 0x0f, 0x11, 0x0f, 0x00, // russian small A 0x01, 0x0e, 0x10, 0x1e, 0x11, 0x11, 0x0e, 0x00, 0x00, 0x00, 0x1e, 0x11, 0x1e, 0x11, 0x1e, 0x00, 0x00, 0x00, 0x1e, 0x10, 0x10, 0x10, 0x10, 0x00, 0x00, 0x00, 0x0e, 0x0a, 0x0a, 0x1f, 0x11, 0x00, 0x00, 0x00, 0x0e, 0x11, 0x1e, 0x10, 0x0e, 0x00, 0x00, 0x00, 0x15, 0x15, 0x0e, 0x15, 0x15, 0x00, 0x00, 0x00, 0x1e, 0x01, 0x0e, 0x01, 0x1e, 0x00, 0x00, 0x00, 0x11, 0x13, 0x15, 0x19, 0x11, 0x00, 0x0e, 0x00, 0x11, 0x13, 0x15, 0x19, 0x11, 0x00, 0x00, 0x00, 0x09, 0x0a, 0x0c, 0x0a, 0x09, 0x00, 0x00, 0x00, 0x07, 0x09, 0x09, 0x09, 0x11, 0x00, 0x00, 0x00, 0x11, 0x1b, 0x15, 0x11, 0x11, 0x00, 0x00, 0x00, 0x11, 0x11, 0x1f, 0x11, 0x11, 0x00, 0x00, 0x00, 0x0e, 0x11, 0x11, 0x11, 0x0e, 0x00, 0x00, 0x00, 0x1f, 0x11, 0x11, 0x11, 0x11, 0x00, // russian small Pe // 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler // 0x00, 0x00, 0x1e, 0x11, 0x11, 0x1e, 0x10, 0x00, // russian small Re 0x00, 0x00, 0x0e, 0x11, 0x10, 0x11, 0x0e, 0x00, 0x00, 0x00, 0x1f, 0x04, 0x04, 0x04, 0x04, 0x00, 0x00, 0x00, 0x11, 0x11, 0x0f, 0x01, 0x0e, 0x00, 0x00, 0x00, 0x1f, 0x15, 0x15, 0x1f, 0x04, 0x00, 0x00, 0x00, 0x11, 0x0a, 0x04, 0x0a, 0x11, 0x00, 0x00, 0x00, 0x12, 0x12, 0x12, 0x1f, 0x01, 0x00, 0x00, 0x00, 0x11, 0x11, 0x0f, 0x01, 0x01, 0x00, 0x00, 0x00, 0x15, 0x15, 0x15, 0x15, 0x1f, 0x00, 0x00, 0x00, 0x15, 0x15, 0x15, 0x1f, 0x01, 0x00, 0x00, 0x00, 0x18, 0x0e, 0x09, 0x09, 0x0e, 0x00, 0x00, 0x00, 0x11, 0x11, 0x1d, 0x15, 0x1d, 0x00, 0x00, 0x00, 0x10, 0x1e, 0x11, 0x11, 0x1e, 0x00, 0x00, 0x00, 0x1e, 0x01, 0x0f, 0x01, 0x1e, 0x00, 0x00, 0x00, 0x17, 0x15, 0x1d, 0x15, 0x17, 0x00, 0x00, 0x00, 0x0d, 0x13, 0x0f, 0x05, 0x09, 0x00, // russian small Ya 0x0a, 0x00, 0x1f, 0x10, 0x1e, 0x10, 0x1f, 0x00, // russian Yo 0x0a, 0x00, 0x0e, 0x11, 0x1e, 0x10, 0x0f, 0x00, // russian small Yo // 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00, // filler 0x00, 0x04, 0x0a, 0x15, 0x0a, 0x04, 0x00, 0x00 // filler }; static uint8_t lcd_draw_part = 0; static uint8_t lcd_ch; static uint8_t lcd_draw_string[16] = { 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87 }; void TIM4_IRQHandler() { if (TIM_GetITStatus(TIM4, TIM_IT_Update) != RESET) { TIM_ClearITPendingBit(TIM4, TIM_IT_Update); // , part = 0 - 0..7, part = 1 - 8..15 LCD_gotoxy(0, (lcd_draw_part ? 0 : 8)); LCD_write_data(0x20); LCD_write_data(0x20); LCD_write_data(0x20); LCD_write_data(0x20); LCD_write_data(0x20); LCD_write_data(0x20); LCD_write_data(0x20); LCD_write_data(0x20); // CGRAM 8 for(uint8_t i = 0; i < 8; i++) { lcd_ch = lcd_draw_string[i + (lcd_draw_part ? 8 : 0)]; if(lcd_ch > 127) LCD_load_symbol(i, cmap + 8 * (lcd_ch & 0x7f) ); } // LCD_gotoxy(0, (lcd_draw_part ? 8 : 0)); for(uint8_t i = 0; i < 8; i++) { lcd_ch = lcd_draw_string[i + (lcd_draw_part ? 8 : 0)]; if(lcd_ch < 128) LCD_write_data(lcd_ch); else LCD_write_data(i); } lcd_draw_part ^= 0x01; } } void LCD_start_fps() { RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM4, ENABLE); TIM_TimeBaseInitTypeDef timerInitStructure; timerInitStructure.TIM_Prescaler = 48-1; timerInitStructure.TIM_CounterMode = TIM_CounterMode_Up; timerInitStructure.TIM_Period = 20000; // 20ms/isr timerInitStructure.TIM_ClockDivision = TIM_CKD_DIV1; timerInitStructure.TIM_RepetitionCounter = 0; TIM_TimeBaseInit(TIM4, &timerInitStructure); TIM_Cmd(TIM4, ENABLE); TIM_ITConfig(TIM4, TIM_IT_Update, ENABLE); NVIC_InitTypeDef nvicStructure; nvicStructure.NVIC_IRQChannel = TIM4_IRQn; nvicStructure.NVIC_IRQChannelPreemptionPriority = 0; nvicStructure.NVIC_IRQChannelSubPriority = 2; nvicStructure.NVIC_IRQChannelCmd = ENABLE; NVIC_Init(&nvicStructure); } In this case, it is very important to properly configure the display control, and use close to the minimum exchange timings, as well as, if possible, an 8-bit interface to the display (although according to tests, the 4-bit interface does not load the controller too much). You must also use the read signal BUSY on line D7 from the display, to reduce the waiting time for its reaction.
How it looks on a real display can be viewed on the video below:
The top line is controlled by a quick redraw and displays information from CGRAM. The line contains graphically drawn characters from the code table CP866 with codes 0x80-0xFF, the pseudografics are replaced with chess diamonds. In the bottom line there are symbols of the built-in character generator of the display and a number of their codes.
The disadvantages of the method:
When the update frequency is below 25Hz, flickering is noticeable when viewed at an angle, while looking straight up it is not visible vertically.
Also slightly decreases the contrast of the image from the display, but it is almost not noticeable.
Source: https://habr.com/ru/post/403831/
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