USB LCD/VFD Controller Hardware

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The USB LCD/VFD controller are using a PIC16F873 to control the LCD module.
A FT232BM chip are used to convert the USB signal to serial TTL level.

Following is the main component used:

Schematic

The circuit are quite simple, you can click here to view the schematic chart in pdf format.
You can also click here to download the design file in Protel99 format.

PCB Layout

The PCB design can fit most size of LCD/VFD. So, you can order some PCB and build a backpack for any kind of LCD/VFD modules.
Here is my PCB Layout in PDF:

For your convenes, I also provide the PCB Layout in Protel99 SE format so that you can easily modify it to match your needs. 
Click here to download.

In order to improve the layout of PCB, I also made a PCB use SMD componments. Click to donwload the PCB and SCH .

Bill of Material

Part Type Designator Footprint Description Comment
33p C1 RAD-0.1 Capacitor
27p C10 RAD-0.1 Capacitor
27p C11 RAD-0.1 Capacitor
0.1u C12 RAD-0.1 Capacitor
33p C2 RAD-0.1 Capacitor
10nF C3 RAD-0.1 Capacitor
0.1u C4 RAD-0.1 Capacitor
33nF C5 RAD-0.1 Capacitor
0.1u C6 RAD-0.1 Capacitor
0.1uF C7 RAD-0.1 Capacitor
0.1uF C8 RAD-0.1 Capacitor
0.1uF C9 RAD-0.1 Capacitor
Power JP1 SILFKV4S 4 Pin Header
Keypad JP2 SIP8 8 Pin Header
PWR-SEL JP3 SIP-3 3 Pin Header
GPO JP4 SIP-4 4 Pin Header
LEDS JP5 SIP-4 4 Pin Header
LCD BKLIGHT JP6 SIP-4 2 Pin Header
USB_SOCKET JP7 USB_SOCKET-B USB Type A Socket
ICSP JP8 SIP-6 6 Pin Header
BC547 Q1 TO92C NPN BJT
BC547 Q2 TO92C NPN BJT
BC547 Q3 TO92C NPN BJT
IRFU9110 Q4 TO251H P-Channel FET
27 R10 AXIAL-0.4 Resistor
1.5K R11 AXIAL-0.4 Resistor
47K R12 AXIAL-0.4 Resistor
470 R13 AXIAL-0.4 Resistor
2.2K R14 AXIAL-0.4 Resistor
10K R15 AXIAL-0.4 Resistor
220 R16 AXIAL-0.4 Resistor
220 R17 AXIAL-0.4 Resistor
1K R18 AXIAL-0.4 Resistor
10 R2 AXIAL-0.4 Resistor
1K R3 AXIAL-0.4 Resistor
2.7K R4 AXIAL-0.4 Resistor
1K R5 AXIAL-0.4 Resistor
1K R6 AXIAL-0.4 Resistor
10 R7 AXIAL-0.4 Resistor
10 R8 AXIAL-0.4 Resistor
27 R9 AXIAL-0.4 Resistor
PIC16F873 U1 DIP28-S Microchip PIC16F873
FT232AM U2 LQFP32 USB-RS232 Controller
93C46 U3 DIP8 EEPROM
HD44780 U5 CONN16 HD44780 LCD Panel
HD44780 U6 SIP16 HD44780 LCD Panel
20MHz Y1 XTAL-1 Crystal
6M Y2 XTAL-1 Crystal

Connectors

There are several connectors on the PCB, they are for particular use. This session will describe the pin of these connectors.

JP1 - Power Connector
For internal mount, you should plug a stand 3.5' floppy driver power cable in this socket to power the unit. Only the 5V output are used.

The external Power are not need in most case.

JP2 - Keypad Connector
To connect a 4x4 keypad here.

Pin Layout:

R1 R2 R3 R4 C1 C2 C3 C4

Key Code:

  C1 C2 C3 C4
R1 A B C D
R2 F G H I
R3 K L M N
R4 P Q R S

JP3 - Power Selector
Use this jumper to select the power of LCD/VFD from USB bus or Power Connector(JP1).

JP4 - GPO Connector
This connector are used to GPO output. Can be used to drive the LED.
Pin Number Feature
1 +5V
2 GPO 1
3 +5V
4 GPO 2

JP5 - TX/RX LED socket To display the TX/RX status of USB interface.

JP6 - Alter LCD Backlight Connector

JP7 - USB Sockect A type-A USB socket.

JP8 - ICSP Sockect For use any ICSP device to programmer the on board MCU.

Pin Number Feature
1 GND
2 VCC
3 PGC
4 PGD
5 MCLR
6 PGM

U5 - LCD/VFD Connector
Connector to connect to a 8x2 or 7x2 LCD/VFD Module.

U6 - LCD/VFD Connector
Connector to connect to a 16x1 LCD/VFD module.

, Jerry Han