[Bug]: On SIM PWR panel, PC Pwr is a locking switch; should be a momentary (ON)-OFF-(ON)

[eHanseJoerg]

Discord Username

Ulukaii

Bug Summary

On the SIM PWR panel, the PC PWR switch is specified as a NKK locking switch. However, PC motherboards expect a momentary signal from a power button to start / shutdown.

This is in contrast to the continuous signal of an ATX PSU itself. Therefore, a locking switch for MASTER ON is correct; a locking switch for PC PWR is not.

Expected Results

Switch position and PC PWR state never contradict each other

Actual Results

Due to the switch being a locking switch, contradictions between switch position and PC PWR state may arise: for example after a software shutdown via Windows, the PC PWR switch will remain in the ON position while the PC is shutdown. When the switch would then be moved into the OFF position, the PC would start again, as a power cycle pulse is sent to the PC!

This is also not recoverable via software, because the Arduino on the pit mgmt system does not know the PC power state.

Replacing the switch with a momentary switch will solve all these problems.

Screenshots/Images/Files

Applicable Part Numbers

OH10A1A1-1

Release Version

v0.2.0

Category

Mechanical (Structure/Panels/Mechanisms)

Applicable End Item(s)

Left Console (LCON)

Built to print?

• I built (or attempted to build) the part to the OpenHornet print without any deviations.
• I am not building this part to the OH print. (List deviations in detail in the Miscellaneous Info text area below.)

Miscellaneous Info

First, I used the specified NKK switch and experimented extensively with software logic to achieve acceptable behaviour. But because the PC power state is not known to the Arduino, this is a fundamental limitation

[jrsteensen]

Walk me through the path to the PC for this - I haven't seen a PC in many years that uses a maintained on/off/reset switch. For example, my current PC uses two momentary pushbuttons. My laptop uses one momentary pushbutton.

[eHanseJoerg]

@jrsteensen not sure what you mean... but using a momentary switch is exactly the solution suggested.

I coded the Arduino sletch for it and it basically sends the power on/off pulse whenever the switch is selected momentary ON

[eHanseJoerg]

This is a simple code snippet for a momentary pushbutton that can be embedded into the sketch:

#include <Bounce2.h>
#define SIMPWR_PCPWR 		  A3    
#define SIMPWR_PCRESET 		A2    
#define EXT_ACC1_PCPWR		4      
#define EXT_ACC2_PCRESET	5

(...)

const unsigned long POWER_PULSE_DURATION = 100;        // 100ms pulse
const unsigned long RESET_PULSE_DURATION = 250;        // 250ms pulse
const int PWM_VALUE = 255;                                                   // Max PWM value to ensure full signal at optocoupler

Bounce pcpwr = Bounce();
Bounce pcreset = Bounce();

(...)

void simpwr_pcpwr() {
  pcpwr.update();
  
  if (pcpwr.changed()) {
    if (pcpwr.read() == LOW) {                                           // Switch is currently being pressed 
        analogWrite(EXT_ACC1_PCPWR, PWM_VALUE);
        delay(POWER_PULSE_DURATION);
        analogWrite(EXT_ACC1_PCPWR, 0);
        delay(3000);                                                     // Inhibit secondary inputs for 3s
        Serial.println("PC power switch unblocked");
    }
  }
  
}


void simpwr_pcreset() {
  pcreset.update();
  
  if (pcreset.changed()) {
    if (pcreset.read() == LOW) {                                        // Switch in RESET position
      analogWrite(EXT_ACC2_PCRESET, PWM_VALUE);                        
      delay(RESET_PULSE_DURATION);
      analogWrite(EXT_ACC2_PCRESET, 0);  // Turn off
    }
  }
}

[eHanseJoerg]

NKK S8AW is a (ON)-OFF-(ON) switch that can be a drop-in replacement for the currently used S3AL

https://www.mouser.de/ProductDetail/NKK-Switches/S8AW?qs=tHAycHUhUlcAOsSQZQV2og%3D%3D&srsltid=AfmBOop1LxOdWqcidQSVnlEHa-_G1jgX6Rva27s3gRNOi1UtaX9KQnM6