Arduino based ATX Power Supply Unit controller

You can use this solution as a Power Supply Unit controller for Raspberry Pi, Terasic DEx boards or any other SoC projects requiring external power.

Initially this project was developed as a part of "MachineKit on DE10-Nano" project.

Default controller type is Arduino Mini Pro 5V, PS is PicoPSU.

WARNING: do not connect both 5V from ATX +5VSB and serial programmer the same time when you are flashing controller !!!

Wiring diagram

Configuration

// set to 1 if you want to set HIGH gpio signal for external hardware
// before power down and wait for confirmation signal
// if 0 power will be turned off immediately
#define PSUC_USE_CONFIRMATION_GPIO 1

// set to 1 if you want to use arduino on-board led
#define PSUC_USE_ONBOARD_LED 1

// set to 1 if you want to use external (case) led
#define PSUC_USE_EXTERNAL_LED 1

// IMPORTANT!!! this is depends on your ATMEGA->[ATX PS_ON PIN] hardware implementation
// set it to LOW if you connected cpu directly to PS_ON
// set to HIGH if you used NPN transistor switch
#define PSUC_PSON_SIGNAL HIGH

Workflow

Application implements a simplest state machine:

GPIO is enabled (by default)

0. turn on, init PSUC and go to 1
1. sleep and wait for signal on button line, if button is pressed go to 2
2. turn on atx power supply and go to 3
3. sleep and wait for signals on button and gpio lines, if received gpio request go to 5, if button is pressed go to 4
4. run 60 seconds and check states for button and gpio lines, if gpio request is received go to 5, if button is pressed for < 10 seconds go to 3, if more than 10 seconds goto 5. after 60 seconds of inactivity on all lines go to 3
5. turn off atx psu and go to 1

GPIO is disabled

0. turn on, init PSUC and go to 1
1. sleep and wait for signal on button line, if button is pressed go to 2
2. turn on atx power supply and go to 3
3. sleep and wait for button signal, if button is pressed go to 4
4. turn off atx psu and go to 1

Notes

Theoretically you can exclude NPN switch and connect PS_ON to arduino pin directly

In this case change

#define PSUC_PSON_SIGNAL HIGH

to

#define PSUC_PSON_SIGNAL LOW

PLEASE do not forget to check current consumption on PS_ON pin for your PSU, for example (my!) PicoPSU consumes only 6 ma. Atmega pin maximum is 40 ma.

TODO

• implement IPMI ?
• get rid of arduino bootloader and implement watchdog ?