> ## Documentation Index
> Fetch the complete documentation index at: https://docs.researchanddesire.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Accessory Port

> Technical specifications for the 3.5mm accessory port and custom integration guidelines

The Deepthroat Trainer includes a 3.5mm accessory port that drives compatible vibrating accessories for real-time, performance-based reinforcement.

## Official accessories

We offer vibrating plugs and wands that connect directly to the accessory port. These accessories auto‑respond to training output—no additional setup required.

<Info>
  The accessory port outputs a modulated signal that scales with training performance. Higher performance produces stronger accessory activation.
</Info>

### Using multiple accessories

When you purchase a Vibe and Wand together, we include a splitter cable so you can use both accessories simultaneously during training. Connect the splitter to the Trainer's accessory port, then plug each accessory into the splitter.

<Tip>
  The wand is designed for external use—hold it in place manually, tuck it into underwear, or position it however works best for you.
</Tip>

<Warning>
  Using multiple accessories increases battery drain. With both accessories connected, expect approximately 2–3 hours of battery life instead of the standard 4 hours. Monitor your battery level during longer sessions.
</Warning>

## Port specifications

The accessory port uses a 4‑conductor TRRS (3.5 mm) jack with the characteristics below.

| Parameter       | Specification                                               |
| --------------- | ----------------------------------------------------------- |
| Connector type  | 3.5 mm TRRS (4‑conductor)                                   |
| Signal output   | First ring (R1)                                             |
| Signal type     | 3.3 V PWM (pulse‑width modulation)                          |
| Maximum current | 200 mA total on the accessory output                        |
| Behavior        | Duty cycle varies dynamically based on training performance |

<Note>
  PWM (pulse‑width modulation) rapidly switches the output on and off. The effective intensity is controlled by the duty cycle (percentage of time the signal is on within each cycle).
</Note>

<Warning>
  When connecting external devices to the trainer, follow these safety guidelines:

  * Never connect high‑voltage or mains‑powered equipment directly to the accessory port.
  * Observe basic electrical safety and comply with all local standards and regulations.
  * Attempt custom integrations only if you are experienced with electronics and accept the associated risks.
  * We officially support only R+D accessories. Custom or third‑party interfaces are used at your own risk.
</Warning>

## Pinout diagram

Refer to the diagram for conductor positions and ground reference. The PWM signal is present on the first ring (R1).

<Frame caption="TRRS pinout diagram for the accessory port">
  <img src="https://mintcdn.com/researchanddesire/LuUTnWrXlgIS5YfY/dtt/specs/_images/image%20(5).webp?fit=max&auto=format&n=LuUTnWrXlgIS5YfY&q=85&s=fe73ac917bab36cb9204bcb37ca9819d" alt="Accessory port TRRS pinout diagram showing the 4-conductor configuration" width="939" height="622" data-path="dtt/specs/_images/image (5).webp" />
</Frame>

<Tip>
  Do not assume a particular CTIA/OMTP conductor order from other audio devices. Always verify against the provided pinout before wiring.
</Tip>

## Custom integrations

Use the steps and reference designs below to safely integrate the accessory output into your own projects.

<Steps>
  <Step title="Plan your load and budget current">
    Determine the accessory or circuit you want to drive and confirm it requires no more than 200 mA from the port. If it needs more current or a different voltage, use a driver stage (example provided below).

    <Check>
      You have identified the expected steady‑state current and any startup/inrush current for your load.
    </Check>
  </Step>

  <Step title="Measure the signal behavior on your device">
    With the trainer active, measure the PWM duty cycle and frequency using a multimeter with duty‑cycle mode or an oscilloscope. Frequency may change across firmware versions; design for a reasonable range rather than a fixed value.

    <Check>
      You recorded typical duty‑cycle values at low, medium, and high performance, and confirmed the signal amplitude is 3.3 V.
    </Check>
  </Step>

  <Step title="Prototype with a safe test load">
    Before connecting a motor or accessory, start with a resistor load within the 200 mA limit (for example, ≥22 Ω at 3.3 V). Verify the port does not exceed temperature limits and that the duty cycle behaves as expected.

    <Warning>
      Do not short the output. Use a current‑limited bench supply or an inline fuse for additional protection when testing.
    </Warning>
  </Step>

  <Step title="Add a driver stage for higher‑power loads">
    If your accessory requires more current or a higher voltage than the port provides, use a logic‑level N‑channel MOSFET or a dedicated low‑side driver. Keep the trainer’s accessory output strictly as a control signal.

    <Check>
      You can fully drive your accessory without exceeding the port’s limits, and the trainer remains cool and stable during operation.
    </Check>
  </Step>

  <Step title="Verify and finalize wiring">
    Confirm conductor assignments against the pinout diagram. Route grounds as required by your design, add flyback protection for inductive loads, and strain‑relieve the TRRS connector.

    <Check>
      With the accessory connected, output intensity smoothly tracks performance without resets, brownouts, or audible artifacts.
    </Check>
  </Step>
</Steps>

### Reference circuits

Use these examples as starting points. Adapt component values to your accessory’s specifications.

#### A. Direct drive (≤200 mA at 3.3 V)

* Connect the accessory between the accessory port’s PWM output (R1) and ground as indicated by the pinout diagram.
* Optional: insert a small series resistor (1–4.7 Ω) to reduce inrush for small DC motors.
* Ensure total draw never exceeds 200 mA.

<Warning>
  If your accessory draws near the 200 mA limit, measure stall current. Many small motors exceed steady‑state current at startup.
</Warning>

#### B. External power with MOSFET low‑side driver (>200 mA or >3.3 V)

* Power the accessory from an external supply sized for its voltage/current.
* Use the accessory port’s PWM (R1) as the MOSFET gate drive.
* Common design elements:
  * Logic‑level N‑MOSFET (e.g., low Rds(on) at 3.3 V gate)
  * Gate resistor: 47–220 Ω
  * Gate‑to‑source pulldown: 100 kΩ
  * Flyback diode across inductive loads (motor/solenoid): fast diode rated for load current
  * Common ground between external supply and the trainer, if required by your measurement and isolation strategy

<Info>
  For galvanic isolation, use an optocoupler or a gate driver with isolation and power the isolated side appropriately. Ensure signal polarity and timing remain compatible with PWM.
</Info>

### Reading the PWM signal with a microcontroller

If you want your project to react to the trainer’s performance rather than drive a load, read the PWM duty cycle with a microcontroller. The examples below measure duty cycle and map it to a 0–100% intensity value.

<CodeGroup>
  ```cpp Arduino theme={null}
  // Reads a 3.3 V PWM signal and computes duty cycle on Arduino (3.3 V boards recommended)
  // Wire the accessory port PWM (R1) to a digital input pin that supports pulseIn measurements.

  const int pwmPin = 2; // PWM signal from accessory port (R1)

  void setup() {
    Serial.begin(115200);
    pinMode(pwmPin, INPUT);
  }

  void loop() {
    // Measure high and low durations (microseconds)
    unsigned long highT = pulseIn(pwmPin, HIGH, 50000); // 50 ms timeout
    unsigned long lowT  = pulseIn(pwmPin, LOW,  50000);
    if (highT > 0 && lowT > 0) {
      float duty = 100.0f * (float)highT / (highT + lowT);
      Serial.print("Duty: ");
      Serial.print(duty, 1);
      Serial.println(" %");
    }
  }
  ```

  ```python Python theme={null}
  # Reads a 3.3 V PWM signal and computes duty cycle on Raspberry Pi using pigpio
  # Requires: sudo apt install pigpio && sudo systemctl start pigpiod

  import time
  import pigpio

  PWM_PIN = 18  # BCM numbering; connect accessory port PWM (R1) here
  pi = pigpio.pi()
  pi.set_mode(PWM_PIN, pigpio.INPUT)

  def measure_duty(pin, interval=0.05):
      # Sample high/low states over a short window and estimate duty
      start = time.time()
      high_time = 0.0
      last_t = start
      last_state = pi.read(pin)
      while time.time() - start < interval:
          state = pi.read(pin)
          now = time.time()
          if last_state == 1:
              high_time += now - last_t
          last_t = now
          last_state = state
      duty = 100.0 * high_time / interval
      return max(0.0, min(100.0, duty))

  try:
      while True:
          d = measure_duty(PWM_PIN)
          print(f"Duty: {d:4.1f} %")
          time.sleep(0.1)
  finally:
      pi.stop()
  ```
</CodeGroup>

<Note>
  If your microcontroller operates at 5 V logic, ensure the input pin is 3.3 V‑tolerant or add a level shifter/buffer. Do not feed 5 V back into the accessory port.
</Note>

## Design guidelines and best practices

* Protect against inductive kickback with a diode across motors and solenoids.
* Keep cable runs short to minimize PWM edge ringing and EMI. Add a small RC snubber at the accessory if needed.
* Use strain relief on the TRRS connector to prevent intermittent connections.
* Validate with a dummy load before attaching a wearable or user‑contact accessory.
* Document your wiring and settings so you can reproduce results across sessions.

<AccordionGroup>
  <Accordion title="The accessory doesn’t respond">
    - Confirm you are connected to the correct conductor (R1) for PWM.
    - Verify the ground reference matches the pinout diagram.
    - Test with a resistor load to rule out accessory faults.
  </Accordion>

  <Accordion title="Output seems weak or inconsistent">
    * Measure actual duty cycle and confirm your driver stage isn’t in a linear region.
    * Check supply voltages and ensure no brownout when the load engages.
    * Reduce cable length or add decoupling close to the load.
  </Accordion>

  <Accordion title="Electrical noise or audible whining">
    * Increase PWM filtering on the load side (RC or LC) if appropriate.
    * Add a gate resistor (47–220 Ω) and minimize loop area on high‑di/dt paths.
    * Mount the flyback diode close to the load terminals.
  </Accordion>
</AccordionGroup>

<Check>
  You have verified current limits, confirmed correct pinout usage, and demonstrated stable operation with both a test load and your final accessory.
</Check>