Bus Pirate v3 LCD adapter hardware design
From DP
Control HD44780 LCDs from the Bus Pirate v3 with this breakout board. The Bus Pirate LCD mode uses an adapter because there aren't enough pins to directly control a character display.
You can build the adapter with a few parts and a bread board, or you can buy it ready-made at Seeed Studio for $xx.xx. Includes a short connector cable. Every sale directly supports open source development of the Bus Pirat
You can get a Bus Pirate LCD adapter v3 for $9.
Read about the design below.
Contents |
Overview
Since the Bus Pirate v3 doesn't have enough pins to drive the HD44780 directly, we had to add a serial shift register to drive it. The board also features hardware Contrast, and Brightness adjustment, as well as software controllable backlight.
Hardware
Click for a full size schematic image. Schematic and PCB were designed with the freeware version of Cadsoft Eagle, download the latest project files from our Google Code project page.
'595 serial shift register
To successfully control the LCD, more pins needed to be added. We tackled this problem by adding the '595 8bit serial shift registrar (IC1), which is decoupled with the 0.1uf capacitor (C1), and also drives the LED (LED1) trough a 1k resistor (R1). It controls the LCD in the 4bit mode, using 4 pins of the '595's output for the D7-D4 LCD pins, and another 3 for the LCD's control pins. The LED (LED1) is driven by the 8th pin of the '595.
Contrast
The contrast 50K trimmer is used to adjust the contrast of your LCD. Turnong it in the counter-clock wise direction will increase the contrast.
Brightness
The anode (A pin) of the backlight LED is connected trough a 10 ohm 'Brightness' trimmer to the 'ANODE' jumper. By leaving the jumper on the pins you will connect the trimmer to 5v power, and by taking it off you'd effectively turn off the LCD backlight.
The cathode (K pin) of the LCD back light is connected to a 2-way jumper 'Cathode' which allows you to connect it directly to ground (GND), or to the collector of the 'T1' NPN transistor. The transistors base is connected to the 'AUX' pin of the Bus Pirate giving you the ability to adjust the backlight trough a PWM software controlled signal.
HD44780 header
Included on the board is the standard 16pin header for HD44780, and compatible LCDs.
Bus Pirate v3 IO header
For simple connectivity, the same 10pin IO header as featured on the Bus Pirate v3 is located on the board. All it takes to connect the two boards is a 10pin flat cable.
PCB
We used the freeware version of Cadsoft Eagle to make the schematic and PCB. Download the latest designs and firmware from the project Google Code page.
- PCB and placement notes
- soldering advise
Partslist
Click for a full size placement image.
| Part | Quantity | Value | Package |
|---|---|---|---|
| ANODE | 1 | Jumper | 1X02 |
| C1 | 1 | 0.1uF | C0805 |
| IC1 | 1 | 74HCT595D | SO16 |
| J1 | 1 | CON_HEADER_1X03-PTH | M1X3 |
| JP1 | 1 | CON_HEADER_2X05-PTH+SHROUDED_A | PINSHRD_PTH_2X05 |
| LCD | 1 | 1X16 | |
| LED1 | 1 | CHIP-LED0805 | |
| PCB1 | 1 | PCB_DP_RECTANGLE-37X60 | DP6037_V1 |
| R1 | 1 | 10K | CA6V |
| R2,R4 | 2 | 1K | M0805 |
| R5 | 1 | 100R | CA6V |
| T1 | 1 | SOT23-BEC@1 |
Get one!
You can get one for $9.00, including worldwide shipping.
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