# RPi-ATX-LCD-Breakout
This board allows you to connect an ATX power supply and a HD44780-compatible LCD
screen to your Raspberry Pi (or others with compatible GPIO layout).
While it does have a 40pin GPIO connector, it will also work with older
26-pin variants of the Pi.
The board was created to provide a convenient interface for two
[Octoprint](http://octoprint.org/) plugins:
[PSUControl](https://github.com/kantlivelong/OctoPrint-PSUControl) and
[LCD-HD44780](https://github.com/Kunsi/Octoprint-LCD-HD44780) (See links on
bottom of this page).
![Board](img/top.jpg?raw=true)
The board itself offers a variety of features:
* Powering the Pi using +5VSB (standby power)
* Switching the PSU on and off using GPIO pin 12
The GPIO pin can be connected to PS_ON directly, or via a transistor. This is
choosable using the three-pin jumper switch.
Alternatively, the PSU can be forced to be on, by using the 2-pin PS_ON
jumper.
* Providing a "is the PSU on"-detection by wiring GPIO pin 11 to the 3v3 rail
of the PSU
* Connecting a character LCD to the Pi
LCD is wired as follows:
- Register Select
- 15
- Enable
- 16
- Data 4
- 21
- Data 5
- 22
- Data 6
- 23
- Data 7
- 24
Data 0-3 pins are not connected. Read/Write select has been wired to GND, so
it's not possible to read data from the LCD screen. Contrast pin is
connected to a potentiometer.
* Allow connecting of two fans, one 5V, one 12V
* Providing screw terminals for GND, +12V, +5VSB and +5V
* Providing a USB outlet powered by +5VSB
Note: All pin numbers use BOARD numbering.
## Cost
Prices are in Euro, and are based on my prototype production cost
Item | Count | Price | Link
----------------|---------:|------:|---
PCB | 1 | 1.70 | [PCBway](https://www.pcbway.com/) got me 10 boards for 17$
Fan connector | 2 | 0.42 |
Pin header | 3+2 wide | 0.09 |
Potentiometer | 1 | 0.38 |
LCD connector | 1 | 0.52 |
Screw terminals | 2 | 0.42 |
Jumper | 1 | 0.03 |
USB connector | 1 | 0.20 |
Transistor | 1 | 0.09 |
Resistors | 1+1+1 | 0.30 |
GPIO connector | 1 | 0.11 | [https://de.aliexpress.com/…/32454935478.html](https://de.aliexpress.com/item/100pcs-lot-2-54mm-Double-Row-Female-12P-Straight-Header-Pitch-Socket-Strip-2X20-Pin/32454935478.html)
ATX connector | 1 | 0.43 |
## Links
* [Octoprint](http://octoprint.org/)
* [OctoPrint-PSUControl](https://github.com/kantlivelong/OctoPrint-PSUControl) by kantlivelong
* [Octoprint-LCD-HD44780](https://github.com/Kunsi/Octoprint-LCD-HD44780) by Kunsi