IOCAN

# Analog Switch Input

## Overview

An **Analog Switch Input** reads a **multi-position switch** on a single analog

pin. Instead of one wire per position, the switch presents a different **voltage**

(or **resistance**) for each position, and this input decodes which position is

selected. Use it for rotary mode switches, multi-button steering controls and

resistor-ladder keypads.

## Prerequisites & hardware

- A switch wired to one analog pin that produces a distinct level per position.

- Know each position's nominal value so you can set the recognition tolerance.

- **External divider:** the input does **not** provide an internal pull-up. In

  **Resistors** mode you fit an **external pull-up** resistor (and optionally a

  pull-down) to turn the switch's resistance into a voltage, and enter those

  resistor values so the controller can work out the switch resistance. In

  **Voltage** mode the switch presents the voltages directly and no divider is

  needed.

## Add it in the app

1. Add a new input and choose **Analog Switch Input** as the type.

2. Select the **pin** the switch is wired to.

3. Give it a clear **alias** (e.g. `Mode Switch`).

4. Choose the **mode** and **range**. The two modes are mutually exclusive — pick

   whichever suits your hardware:

   - **Resistors:** enter the external **pull-up** (and **pull-down**) resistor

     values that form the divider.

   - **Voltage:** enter the **voltage range** (min/max voltage) the position sits

     in.

5. Set the **precision** and, for mechanical switches, the debounce timings.

## Settings reference

> Schema: `config/AdcSwitchConfiguration.proto`.

| Setting | Meaning | Unit | Range / values | Notes |

|---|---|---|---|---|

| **Range** | Input voltage range / scaling reference | — | `5 V`, `Internal 5 V`, `12 V`, `Raw` | Choose to cover the switch's full-scale voltage. `Raw` reports unscaled counts. |

| **Mode** | How the position is defined — the two are mutually exclusive | — | `Resistors`, `Voltage` | `Resistors` = an external pull-up/pull-down divider turns the switch resistance into a voltage; `Voltage` = the position is recognised by its voltage range. Configure only the fields for the mode you choose. |

| **Pull-up** | Value of the **external** pull-up resistor forming the divider | Ω | uint32 | **Resistors mode only.** Tells the controller the divider's upper leg so it can compute the switch resistance. |

| **Pull-down** | Value of the external pull-down resistor | Ω | uint32 | **Resistors mode only.** The lower leg of the divider (optional). |

| **Min voltage / Max voltage** | Voltage range for the position | mV | uint32 | **Voltage mode only.** The window the position's voltage falls in. |

| **Precision** | Matching tolerance for recognising the position | — | uint32 | How close a reading must be to count as this position. Too loose = wrong position; too tight = missed positions. |

| **Enable filter** | Turns on debounce filtering | — | on / off | Recommended for mechanical switches. |

| **Delay** | Debounce delay before a change is accepted | ms | sint32 | New position must be stable this long. |

| **Hold** | Minimum time a position is held | ms | sint32 | Stops rapid re-triggering. |

| **Interspace** | Minimum gap between transitions | ms | sint32 | Ignores transitions closer than this. |

## Common settings

Analog Switch Input also uses the shared settings — alias and pin.

See [Common IO Settings](../Common-IO-Settings.md).

## Example — detect one switch position (Voltage mode)

Each Analog Switch Input recognises **one** position/level. This example detects a

single rotary position that sits at ~2.5 V:

1. Type **Analog Switch Input**, alias `Mode Pos 2`, on the switch's pin.

2. Mode `Voltage`, **Range** `5 V`.

3. **Min/Max voltage** `2300`/`2700` mV — the window around that position.

4. **Precision** moderate so the detent maps cleanly to this position.

5. **Enable filter**, **Delay** `20`, **Hold** `30` to settle between detents.

> To decode every position of a multi-position rotary as its own signal, add one

> Analog Switch Input per position — e.g. a 5-position rotary uses 5 inputs, each

> watching its own voltage range. That is a valid setup but not the typical use;

> most installs detect a single switch level.

## Troubleshooting

- **Wrong position selected / jumps between two:** the levels are too close for the

  **precision** — tighten precision or space the positions further apart.

- **No position recognised:** in Voltage mode the reading is outside **Min/Max

  voltage**; in Resistors mode the entered **pull-up/pull-down** values don't match

  the resistors actually fitted.

- **Position flickers when turning:** enable the filter and raise **Delay** /

  **Interspace**.

- **Voltage doesn't change with the switch (Resistors mode):** check the **external

  pull-up** is fitted — without it the divider produces no voltage.

## Related

- [Analog Input](Analog-Input.md) — single analog voltage rather than a switch.

- [Digital Input](Digital-Input.md) — single on/off contact.

- [Mux Input](Mux-Input.md) — select between several inputs by a selector.