20x4 (20 characters, 4 lines) LCD modules provide a parallel interface and are wired as follows:
1: GND
2: +5V
3: V0
4: RS [A0]
5: R/W [/WR]
6: E [IOSEL inverted]
7: DB0 [D0]
8: DB1 [D1]
9: DB2 [D2]
10: DB3 [D3]
11: DB4 [D4]
12: DB5 [D5]
13: DB6 [D6]
14: DB7 [D7]
15: VDD backlight
16: GND backlight
A variable 4.7k resistor connected to V0 is used to set the display contrast.
A 3.3R resistor is connected between LCD pin 16 and GND if VDD backlight is less than 5V (please check your specs!), otherwise connect pin 16 directly to GND.
Bill of materials:
- PCB 5x7 cm (at least 23 rows)
- 23-pin right-angled male connector
- DIP-14 socket
- DIP-20 socket
- 74x04 hex inverter
- 74x245 octal bidirectional transceiver
- resistor 3.3R (choose according to the LCD specs)
- variable resistor 4k7
- capacitor 100 nF
playing around with the RTC
