LCD1602 address setting
The character generated memory (CGROM) inside the LCD1602 liquid crystal module has stored 160 different dot matrix characters, these characters: Arabic numbers, English letters, commonly used symbols, and Japanese fake names, each character has A fixed code, such as the code of the capital alphabet "A" is 01000001B (41H), showing the display when the module shows the dot matrix character graphics in the address 41h, we can see the letter "a". There is a DDRAM in 1602, that is, the data RAM is displayed, which is used to store the character code to be displayed, a total of 80 bytes.
If you want to display a "A" word in the first line of the LCD1602 screen, you should write the code of the "A" word to the DDRAM 00H address. However, if you want ZD to display data at the 00H address of the DDRAM, you must add 80h, ie 80h, to display data at 01H of DDRAM, you must add 80h of 81H. And so on.
Description of the controller 11 inside the LCD1602
Although the LCD1602 has 16 pins, the main pin programmed is only three, which are: RS (data command selection), R / W (read write selection), E (enable signal); Some programming is actually the initialization, write commands, write data around these three pins.
Command 1: Clear display, command code 01H, and the cursor is reset to the address 00h position. The main function is clear DDRAM and AC values.
Instruction 2: The cursor is reset, the cursor returns to the address 00h. When AC = 0, the cursor, the screen will reply the Home bit.
Command 3: Sets the movement mode of the cursor and the screen. I / D: The direction of movement of the cursor, the right right shift, low level left S: No left or right movement on the screen. High levels indicate valid, low levels are invalid.
Directive 4: Display switch control. The main function is to set the display, cursor and flashing, and off.
Command 5: Cursor or Displacement. No matter how the cursor and the picture move, do not return to DDRAM.
Directive 6: Function Settings Command. Setting the work mode, that is, initialization instructions.
Instruction 7: Character Generator RAM Address Settings. Set the CGRAM address, A5 ~ A0 = 0 ~ 3FH.
Directive 8: DDRAM address settings.
Command 9: Custom Signal and Cursor Address, that is, the busy flag BF value and address counter AC value (BF: is busy, high) is busy, this time the module cannot receive commands or data, if the low level is represented not busy.)
Command 10: Write data, it is divided into two modes. When writing instructions, output RS = 0, RW = 0, D0 - D7 = data, EN changes from high pulses to low pulses, D0 ~ D7 status value output; when writing data, output RS = 1, RW = 0 , D0 - D7 = data, EN changes from high pulses to low pulses, with D0 ~ D7 status value output.
Directive 11: Read data, there are two modes. When reading the status, enter RS = 0, RW = H, EN is high change low pulse, there is a D0 ~ D7 state value output; read data is, input RS = 1, RW = 1, EN is high, low pulse, no Output.
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