PSU tinkering, Part 1

As previously blogged, I've got a couple of 12v 88.7A PSUs that I'm trying to control under arduino. Stage 1 complete - It powers up with a trivial bit of code

/* Arduino control for (ex) server PSU 
 * Andrew Elwell <andrew.elwell@gmail.com> August 2016
 * Released under BSD licence
 */

 /* Controls / Pins based on data sheet available at 
  *  https://belfuse.com/resources/PowerSolutions/SFP1050/bcd20031_ab_sfp1050-12bg.pdf
  *  
  *  A6/B4/C4/D4         +3.3 standby (power to arduino)
  *  A3/B1/B3/C1/C3/D3   Return 
  *  B5(SDA) / C5(SCL)   I2C
  *  B6                  Bring low for PS ON
  *  C6                  AC OK (if high)
  *  D6                  PWR OK (if high)
  *  
  */


#include <wire.h>

int ACOK  = 2;
int PSON  = 3;
int PWROK = 4;
int LED   = 13;

void setup() {
  Wire.begin();                // join i2c bus (address optional for master)
  pinMode(ACOK, INPUT);
  pinMode(PSON, OUTPUT);
  pinMode(PWROK, INPUT);
  pinMode(LED,  INPUT);
  
  digitalWrite(PSON,HIGH) ;   // Stay off until ready
}

void loop() {
  if (digitalRead(ACOK) == HIGH) {
    digitalWrite(PSON,LOW) ;
  } 
  if (digitalRead(PWROK) == HIGH) {
    digitalWrite(LED,HIGH) ;
  } 
}

The one gotcha that I needed to get it working was to also bring PS A0 low (I2C address) and suddenly green led and 12v out!