The **RG3-303S-R15** is a high-performance **rotary coded switch** (often referred to as a rotary selector or DIP rotary switch) manufactured by companies like Copal Electronics (Nidec). These components are designed to provide a binary-coded output based on the physical position of the rotor. ### 1. General Specifications Below is a summary of the technical characteristics of the RG3 series, specifically the 303S-R15 variant. | Feature | Specification | | :--- | :--- | | **Code Type** | Real Binary Code (3-bit/8-position) | | **Number of Positions** | 8 Positions (0 through 7) | | **Actuator Type** | Shaft type (usually for knob attachment) | | **Mounting Type** | Through-hole (PCB Mount) | | **Contact Rating** | 5V DC, 100mA (Switching) / 50V DC, 100mA (Non-switching) | | **Terminal Pitch** | 2.54mm (Standard Breadboard/PCB spacing) | | **Operating Temp** | -25°C to +70°C | --- ### 2. Electronic Functionality The RG3-303S-R15 functions as a digital encoder. As the shaft is rotated to a specific number (0-7), it internally connects specific output pins to the Common (C) pin to represent that number in binary format. #### Logic Truth Table (Real Code) | Position | Pin 1 ($2^0$) | Pin 2 ($2^1$) | Pin 4 ($2^2$) | | :---: | :---: | :---: | :---: | | 0 | OFF | OFF | OFF | | 1 | **ON** | OFF | OFF | | 2 | OFF | **ON** | OFF | | 3 | **ON** | **ON** | OFF | | 4 | OFF | OFF | **ON** | | 5 | **ON** | OFF | **ON** | | 6 | OFF | **ON** | **ON** | | 7 | **ON** | **ON** | **ON** | --- ### 3. Key Electronic Components & Materials * **Gold-Plated Contacts:** To ensure low contact resistance and prevent oxidation over long periods of use. * **Wiping Action Mechanism:** The internal contacts "wipe" across the pads as they turn, which helps clear away dust and ensures a reliable electrical connection. * **Thermoplastic Housing:** Usually made of high-temperature resistant PBT or PPS to withstand wave soldering processes. ### 4. Typical Applications * **Address Setting:** Used in industrial networking (like RS-485 or CAN bus nodes) to set a unique ID for a device. * **Mode Selection:** Selecting between different firmware operating modes on a control board. * **Configuration:** Replacing standard DIP switches where a single rotary interface is more intuitive for the user. --- ### 5. Circuit Integration Example When connecting this to a microcontroller (like an Arduino or STM32), it is standard practice to use **pull-up resistors**. ```cpp // Example: Reading the RG3-303S-R15 state int pin1 = 2; // Connected to Bit 1 (2^0) int pin2 = 3; // Connected to Bit 2 (2^1) int pin4 = 4; // Connected to Bit 4 (2^2) void setup() { pinMode(pin1, INPUT_PULLUP); pinMode(pin2, INPUT_PULLUP); pinMode(pin4, INPUT_PULLUP); } void loop() { // Logic is inverted if using INPUT_PULLUP (Active LOW) int bit0 = !digitalRead(pin1); int bit1 = !digitalRead(pin2); int bit2 = !digitalRead(pin4); int position = (bit2 << 2) | (bit1 << 1) | bit0; } ```