HD44780-based LCD Driver for the STM32
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Specification
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Electronic circuit and PCB
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Benefits
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Controller of Hitachi HD44780 is actually an industry standard and widely used in the manufacture of alphanumeric LCD modules. Analogues of the controller or compatible with him on the interface and command language integrated circuits, produce a lot of companies, including: Epson, Toshiba, Sanyo, Samsung, Philips. An even greater number of firms produce LCD modules based on data controllers. These modules can be found in a variety of devices: measuring instruments, medical equipment, promyshlennnom and processing equipment, office equipment, phones, faxes and copiers.
Alphanumeric LCD modules represent an inexpensive and convenient solution to save time and resources when developing new products, while providing the mapping of a large amount of information in highly visible and low power consumption. The possibility of equipping the LCD backlight modules can operate them in conditions of low or zero illumination, and performance with an extended temperature range (-20 °C ... +70 °C) in complex operating environments, including portable, field and even, sometimes, on-board equipment.
HD44780 controller can potentially control 2 lines of 40 characters each (for modules with with 4 rows of 40 characters used two similar controller), and matrix character 5 x 7 dots. The controller also supports characters with a matrix of 5 x 10 points.
Aware of the widespread popularity of such displays, we decided to develop and open for the engineering community driver HD44780 for innovative Microcontrollers STM32.
Technical details
The driver is written in C + + and requires the use of the library STM32 Standard Peripherals Library v3.3.0. To simplify the development and make the code understandable for those who program in C, we used a minimum of language features C++.
We tried to make the most compact code and implement only the most necessary functionality.
The driver has problems on the basis of conveyor line from a static buffer. Objectives represent a character print command or read command BF and AC. The functionality of reading and defining your own characters in version 1.0 is not implemented.
To connect the interface width of 4 bits.
The driver is free to license GNU Lesser General Public License v3.
How-To
You must perform a series of actions to adapt the code for your platform.
1. Check the settings in the file stm32f10x.h used STM32 family of microcontrollers
/* Uncomment the line below according to the target STM32 device used in your
application */
#if !defined (STM32F10X_LD) && !defined (STM32F10X_LD_VL) && !defined (STM32F10X_MD) && !defined (STM32F10X_MD_VL) && !defined (STM32F10X_HD) && !defined (STM32F10X_XL) && !defined (STM32F10X_CL)
/* #define STM32F10X_LD */ /*!< STM32F10X_LD: STM32 Low density devices */
/* #define STM32F10X_LD_VL */ /*!< STM32F10X_LD_VL: STM32 Low density Value Line devices */
/* #define STM32F10X_MD */ /*!< STM32F10X_MD: STM32 Medium density devices */
/* #define STM32F10X_MD_VL */ /*!< STM32F10X_MD_VL: STM32 Medium density Value Line devices */
/* #define STM32F10X_HD */ /*!< STM32F10X_HD: STM32 High density devices */
/* #define STM32F10X_XL */ /*!< STM32F10X_XL: STM32 XL-density devices */
#define STM32F10X_CL /*!< STM32F10X_CL: STM32 Connectivity line devices */
#endif
Family Connectivity line defined by default.
2. Check the basic configuration driver file HD44780.cpp
/* Basic LCD Driver settings */
#define LCD_PROCESS_IO_FREQ 10000
#define FIFO_SIZE 100
/* Define for boot from Flash */
#define FLASH_BOOT
LCD_PROCESS_IO_FREQ indicates the number of calls the method for processing signals input-output. To display one character must be 11 calls. Accordingly, if you want to print, for example, 10 screens per second and the size of the LCD is a 20x4 character LCD_PROCESS_IO_FREQ = 11 x 10 x 20 x 4 = 8800 calls / second or more. If you used importance leads to the cessation of interruptions, check the calculated value of the counter TIM_Config (), it should be located vpredelah from 0 to 65535, use before. divisor if the calculated value is beyond the permissible.
FIFO_SIZE for such an example must be not less than 20 x 4 + 10 to avoid errors in the derivation of a full screen at once.
3. Check the definition of an instance of HD44780 in main.h
HD44780 lcd(GPIOE, GPIO_Pin_9, GPIOE, GPIO_Pin_8,
GPIOE, GPIO_Pin_11, GPIOE, GPIO_Pin_10,
GPIOE, GPIO_Pin_13, GPIOE, GPIO_Pin_12,
GPIOE, GPIO_Pin_15, 20, 0x00, 0x40, 0x14, 0x54);
Specify the findings, the width of the line and addresses of the first symbols in accordance with your hardware solution.
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