[Bug]: 4A9A1-THROTTLE_CONTROLLER Solenoids Always On

[Arribe]

Discord Username

Arribe

Bug Summary

When external power is applied to the Throttle Controller PCB, the solenoids are powered on.

Expected Results

The solenoids should be able to turn off when the signal pin is set LOW.

Actual Results

The solenoids are always on. I tried the very simple code below, and removing the ESP32 from the controller socket. The solenoids remain on. They also remain on when power cycling the PCB.

#define MAX_SOL_SIG 39 ///< MAX_SOL_SIG
#define IDLE_SOL_SIG 37 ///< IDLE_SOL_SIG

void setup() {
// put your setup code here, to run once:
pinMode(IDLE_SOL_SIG, OUTPUT);
pinMode(MAX_SOL_SIG, OUTPUT);

digitalWrite(IDLE_SOL_SIG, LOW);
digitalWrite(MAX_SOL_SIG, LOW);
}

void loop() {
// put your main code here, to run repeatedly:
digitalWrite(IDLE_SOL_SIG, LOW);
digitalWrite(MAX_SOL_SIG, LOW);
}

Screenshots/Images/Files

No response

Applicable Part Numbers

4A9A1-THROTTLE_CONTROLLER

Release Version

v0.2.0

Category

Electrical (PCBs/Wiring/etc)

Applicable End Item(s)

Throttle

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

No response

[John Steensen]

• Evaluate PCB circuit to see if there is a PCB error.

[Sandra Carroll]

I think you can resolve this with a different MOSFET.
VGS is what turn's on/off the MOSFET, in this case you're using a P-CHANNEL Mosfet

"Vgs is the voltage applied between the gate and source terminals of the MOSFET. In MOSFET operation, Vgs is a critical parameter that determines whether the MOSFET is in the "on" or "off" state. For an NMOS MOSFET, a positive Vgs turns the device on, while for a PMOS MOSFET, a negative Vgs is required."

so PMOS (P CHANNEL) needs a VGS that is negative with respect to the Drain. the Drain here is +5V and the Gate is tied to Ground. (since the gate is negative with respect to the drain it's on. the ESP32 is a 3.3V IC, 3.3V is still negative with respect to the Drain.

you need a -0.55v (4.45v with a drain of 5v ) to turn it off which the ESP32 cannot deliver.

you can see here in a schematic used for this IC

they tie gate high not low

simple solution is find a MOSFET with a VGS that allows a 3.3v level to work and replace the MOSFET with it.

You should be able to test this Appling 5V (12V would be better to be sure we've meet the conditions for VGS) to the gate. it should then turn off

the PCB fix would be to do the same if you did not want to change the MOSFET

changing the MOSFET is an alternative.