UART LIN Transceiver : Working,Applications,Manufacturers

Introduction : A UART LIN Transceiver provides a hardware interface that converts general serial UART communication to LIN bus signaling. This enables a microcontroller or embedded UART interface to communicate over a LIN network.

How UART to LIN Transceiver Works

It is a specialized integrated circuit (IC) that acts as the physical interface between a microcontroller’s standard serial port (Universal Asynchronous Receiver/Transmitter - UART) and the physical Local Interconnect Network (LIN) bus.

While the microcontroller handles the logical protocol (framing, scheduling and error checking), it operates at low logic voltages (3.3V or 5V). The LIN bus operates at the vehicle’s battery voltage (typically 12V). The transceiver bridges this voltage gap.

As the name suggests, it connects one side with UART port (Tx, Rx) and the other side with LIN bus (single data line plus ground line). Let us understand working of UART-LIN converter.

1. UART to LIN : On the transmit side, microcontroller sends a stream of bits via its UART Tx pin. Transceiver receives these low voltage signals and drives the LIN bus line to battery voltage (i.e. recessive/logic 1) or pulls it to Ground (i.e. Dominant/Logic 0). Appropriate LIN frame fields are also constructed before transmission over LIN bus.
2. LIN to UART : On the receive side, transceiver monitors voltages on the single LIN bus wire. Internal comparator detects whether the bus voltage is dominant (near 0v) or recessive (near 12V). It steps high voltage down to logic levels (i.e. 3.3V/5V) and sends the resulting bit stream to UART Rx pin of the microcontroller.

LIN has a specific “Go-to-Sleep” command to save energy. The transceiver itself is usually identical for Masters and Slaves. The difference is determined by an external pull up resistor (1 KOhm for Master and 30 KOhm for Slave) often integrated or switched by the transceiver IC.

Applications

The UART LIN transceivers are used in cost sensitive “mechatronic” subsystems for following or similar applications.

• Door Modules: Controlling window lifters, door locks and mirror adjustments.
• Seat Control: Communicating with seat positioning motors and occupancy sensors.
• Climate Control: Driving stepper motors for air vent flaps.
• Lighting: Controlling “smart actuators” for rear lights.
• Switch Panels: Reading the status of buttons on the steering wheel or dashboard.

Manufacturers

Following are some of the companies which manufacture UART LIN Transceiver device.

Summary: In summary, a UART LIN Transceiver enables seamless integration of UART based microcontrollers or systems with LIN networks. It offers a simple, cost effective path to leverage LIN’s networked communication features without major redesign.