1602 LCD adopts standard 14 pins(no backlight) or 16pins(with backlight) interface, Instruction of each pin interface is as follows:

Transcription

1 LCD 1602 Shield

2 Description: Arduino LCD 1602 adopts 2 lines with 16 characters LCD, with contrast regulating knob, backlight optional switch, and with 4 directional push-buttons, 1 choice button and1 reset button. It simplifies the circuit, and you can use it by plugging it in the controller Arduino UNO or its compatible boards. Parameters 1: Display capacity: 16*2 characters 2: IC operating voltage: V 3: Operating current: 2.0mA(5.0V) 4: Best working voltage for module:5.0v. 5: Character size: (W H)mm 6: Module size: 20.5mm 41mm 7: Module weight: 57g Pins functions 1602 LCD adopts standard 14 pins(no backlight) or 16pins(with backlight) interface, Instruction of each pin interface is as follows: Explanation of each pin: The first pin :VSS means GND The second pin: VDD connect +5v The third pin: VL is the terminal of LCD for adjusting the contrast. Connecting anode, the contrast is weak; connecting GND, contrast is high. Contrast is too high which will result in ghost. You can use a 10k potentiometer to adjust the contrast in operation. The fourth pin: It is register choice. High level, choose data register, Low level, choose instruction register. The fifth pin: R/W is signal wire of read and write. High level, execute read, Low level, execute write. When RS and R/W are at low level simultaneously, you can write command or show address. When RS&R/W are at high level simultaneously, you can read the busy signal; When RS is at high level and R/W is at low level, you can write data. The sixth pin; E terminal is enable terminal. When E terminal becomes from high level to low

3 level, LCD module executes command. The seventh pin: D0 to D7 is 8 pin bi-directional data cable The fifteenth pin: Black light anode The sixteenth pin: Black light cathode 1602 LCD command instructions Inside the module, there are 11 commands as follows: Sequence number of the command is RS R/W D7 D6 D5 D4 D3 D2 D1 D LCD s operation of 'read and write, screen, cursor are executed by commands.(instructions: 1 is high level, 0 is low level Command 1: clear screen, command code 01H, cursor resets to the address 00H. Command 2: Cursor resets, cursor returns to the address 00H Command 3: Cursor and display mode set I/D, cursor moves, high level moves right, low level moves left. S: All the characters of Screen will move right or left or not. High level is effective, low level is noneffective. Command 4: Show on-off control. D: Control overall on-off, high level shows on, low level show off. C: control cursor on-off, high level means with cursor, low level means without cursor. B: control cursor with blink or not, high level means blink, low level means without blink. Command 5: Cursor or display shift S/C. High level, move the characters displayed, low level, move cursor Command 6: Function set command DL: high level with 4 pins cable, low level with 8 pins cable N: Low level, single line display, high level, double lines display F: low level shows 5*7 dot character, high level shows 5*10 dot character. Command 7: Address setting of dot character generator -RAM Command 8: DDRAM address set Command 9: Read the busy signal and cursor address BF: shows busy, high level means busy, at this moment module can t receive command or data. If low level, it means free. Command 10: Write data Command 11: Read data

4 Time sequence chart of IC compatible with HD44780 is as follows: Read status, input RS=L,R/W=H,E=H, output D0 D7=Status character Write command, input RS=L,R/W=L,D0 D7=command code,e=high pulse, output: / Read data, input RS=H,R/W=H,E=H, output : D0 D7=data Write data, input RS=H,R/W=L,D0 D7=data,E=high pulse, output: / Time sequence chart of read operation Time sequence chart of write operation 1602 LCD reset initialization process Delay 15mS Write command 38H( Don t test busy signal) Delay 5mS Write command 38H( Don t test busy signal) 5mS Delay 5mS Write command 38H( Don t check busy signal) Every time write command, read and write data, need to test busy signal

5 Write command 38H, shows mode set Write command 08H, show close Write command 01H, show clear Write command 06H, show cursor movement set Write command 0CH, show on and cursor set KEYPAD testing... pressing 5.Arduino example as follows: //example use of LCD4Bit_mod library #include <LCD4Bit_mod.h> //create object to control an LCD. //number of lines in display=1 LCD4Bit_mod lcd = LCD4Bit_mod(2); //Key message char msgs[5][15] = "Right Key OK ", "Select Key OK ", "Up Key OK ", "Down Key OK ", "Left Key OK " ; int adc_key_val[5] =30, 150, 360, 535, 760 ; int NUM_KEYS = 5;

6 int adc_key_in; int key=-1; int oldkey=-1; void setup() pinmode(13, OUTPUT); //we'll use the debug LED to output a heartbeat lcd.init(); //optionally, now set up our application-specific display settings, overriding whatever the lcd did in lcd.init() //lcd.commandwrite(0x0f);//cursor on, display on, blink on. (nasty!) lcd.clear(); lcd.printin("keypad testing... pressing"); void loop() adc_key_in = analogread(0); digitalwrite(13, HIGH); key = get_key(adc_key_in); // read the value from the sensor // convert into key press if (key!= oldkey) // if keypress is detected delay(50); // wait for debounce time adc_key_in = analogread(0); // read the value from the sensor key = get_key(adc_key_in); // convert into key press if (key!= oldkey) oldkey = key; if (key >=0) lcd.cursorto(2, 0); //line=2, x=0 lcd.printin(msgs[key]); //delay(1000); digitalwrite(13, LOW); // Convert ADC value to key number int get_key(unsigned int input)

7 int k; for (k = 0; k < NUM_KEYS; k++) if (input < adc_key_val[k]) return k; if (k >= NUM_KEYS) k = -1; // No valid key pressed return k;