The lcm module is a dedicated chip control center, the role of the decoder input from the MPU command word into a variety of high-level pulse having a constant width signal, thereby controlling the corresponding circuit, it changes state, complete control the corresponding function module.
MPU sent the script (with R / W, RS signal) into the instruction decoder decodes. The instruction decoder followed by a combinational logic circuit and a stabilizing signal is applied subsequent to the RS flip-flop, the flip-flop output control chip of the module operation.
The operation of the chip MPU total of 11 instructions, can be divided into four broad categories: display function setting command, address setting instructions, data transfer instructions and other type of instruction (such as reading BF).
① Display Function Set instruction includes three display mode: line 5 × 8 dot matrix, two lines of 5 × 8 dot matrix, line 5 × 11 dot matrix format; ② cursor display: do not show, flashing display, lit display; ③ left or right a display control; ④ shift display return after treatment; ⑤ clear the screen. With these instructions, the lcd module can be achieved in a variety of display control.
Address set instruction and data transfer instructions with the conduct, you can achieve MPU and data transfer between RAM. The MPU chip data transfer operation, first send the address set instruction, determine the selection DDRAM or CGRAM data transmission, and the address is written to the counter by setting the number of AC, the AC for RAM addressing operation. The MPU RAM read and write commands sent, can control the display character. MPU BF is an instruction detection, but does not require instruction decoding operations directly in MPU I / O port operation can be completed 3.1 has been introduced, not repeat them here. When the LCD drive control instruction to complete a chip, through the internal circuit generates a high signal BFRESET, the BF is reset, waiting for the next instruction.
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