Introducing Atmel’s new LIN family for in-vehicle networking

LIN (Local Interconnect Network) is a serial network protocol used for communication between various automobile components to enable comfort, power-train, infotainment sensor, and actuator applications. The LIN Consortium was founded by five automakers (BMW, Volkswagen Audi Group, Volvo Cars, DaimlerChrysler) in the late 1990s, with the first fully-implemented version of the new LIN specification (1.3) published in November 2002. Version 2.0 was later introduced in September 2003, offering expanded capabilities and support for additional diagnostics features.

Fast forward 11 years later, Atmel is excited to announce its next-generation family of LIN transceivers, system basis chips (SBC) and voltage regulators for a wide-range of vehicle applications. The new family is the industry’s first to comply with the new original equipment manufacturer (OEM) hardware recommendations and provide scalable functionality to improve the overall system cost.

“As the leading provider of automotive LIN ICs, Atmel is committed to bringing more innovative LIN products to the market,” said Claus Mochel, Atmel Marketing Director for Automotive High Voltage Products.

All the new devices in this new family feature an LDO with outstanding minimum supply voltage of 2.3V combined with linear mode current of 130uA to support data storage even during an unexpected shut down. This new family is compliant with the latest standards including LIN 2.0, 2.1, 2.2, 2.2A and SAEJ2602-2. Some members of the family also include application specific functions such as relay drivers, watchdog, high-side switches and wake up inputs to enable system designers to build innovative in-vehicle network applications in next-generation automobiles.

The devices are available in DFN packages with heat-slug and wet-able flanks to support optical solder inspection. These next-generation devices also provide a family package footprint so that designers can upgrade their designs with various devices within the LIN SBC family.

“Our expanded LIN portfolio includes pin-outs that are the first to support the new OEM hardware recommendations enabling system designers to develop differentiated LIN systems in next-generation vehicles. Atmel’s LIN family footprint makes it easier to migrate upwards and devices in the family offer application-specific functionality for various LIN-connected applications such as window lifters, sun-roofs, trunk opener or seat controls,” Mochel added.

Key features of the ATA6632/33/34 include:

• +3.3V/5V/85mA LDO suitable for usage with low-cost multi layer ceramic capacitors
• 2.3V lowest operating voltage
• Very low current consumption in linear mode
• Sleep current; Normal mode current
• DFN 8 (3x3mm) and DFN16 (3*5.5mm), wet-able flanks included, allowing automatic optical inspection of the solder joint

In order to accelerate the design development, an evaluation kit is also available to support the new LIN devices. The ATAB663xxxA development kit allows designers to quickly start designing with Atmel’s LIN family. The kit is easy-to-use with a pre-defined set-up. All pins are easily accessible for quick testing. The kits allow designers to select master or slave operation with a mounting option for LIN pull-up resistor and series diode.

Those interested will be happy to learn that samples for all family members are now available. You can find more detailed information — including datasheets and request forms — here.

Heading to Munich next week for Electronica 2014? Cruise on over to the Atmel booth — located in Hall A5, #542 — to discover how we’re bringing the IoT to the connected car though simple, touch-enabled human machine interfaces. There, you will find a number of automotive demos, including a door handle powered by Atmel’s fourth generation LIN device that features a curved touch-enabled glass display, providing excellent multi-touch performance for future automotive applications, and utilizing Atmel’s XSense and the maXTouch 2952T.

 

Atmel’s Rob Valiton talks automotive

Rob Valiton, Senior VP and General Manager at Atmel, was recently interviewed by Alix Paultre of Power Systems Design.

During the podcast – which can be heard here – the two spoke about various issues surrounding automotive systems and the multiple, often conflicting challenges involved in designing for the application space.

The interview was conducted in the midst of CES 2014, shortly after Atmel officially unveiled its AvantCar curved touch screen console concept. 

The fully functional console features two large curved touchscreen displays – without mechanical buttons. Instead, the touchscreens integrate capacitive touch buttons and sliders, allowing users to navigate general applications typically found within an automotive center console.

As we’ve previously discussed on Bits & Pieces, Atmel’s extensive automotive portfolio encompasses a wide range of products including body electronics, networking and access systems, as well as engine, lighting and entertainment components.

 More specifically, our components are designed to fit small footprints, consume very little power and operate in high temperature and electromagnetic environments. To be sure, Atmel’s highly integrated designs can help save manufacturers significant component costs and months of development, integration and prototype time.

“Atmel’s broad product portfolio ranges from low-cost, entry level devices to advanced, highly integrated ICs with a broad range of functionalities, extensive connectivity, refined interfaces and strong security,” and Atmel engineering rep told Bits & Pieces. “Our products are designed in state-of-the-art BCDMOS, BDC-on-SOI, or non-volatile CMOS technologies and meet strict automotive qualification standards.”

Interested in learning more about Atmel’s automotive portfolio? You can check out our automotive-qualified category breakdown below:

• Microcontrollers (MCUs)
• 
Serial EEPROMs

• Touch (maXTouch)
• Broadcast radio
• 
CAN/VAN networking
• Car access
• Drivers/high temperature ICs
• 
Battery management
• LIN networking

Two-Wire LIN networking with Atmel (Part 3)

In the first part of this series, we took a closer look at the basics of LIN networking, the key parameters for a two-wire LIN (Atmel) solution and the details of a LIN Bus power supply. In the second part of this series, we discussed various aspects of slave node current consumption, specifically, system clock frequency, sleep mode power management and LIN scheduling power management.

And today we’re going to talk about slave node buffer capacitance, LIN Bus data protocol and a multi-slave evaluation network.

“While an important piece of the two-wire LIN equation, sizing of the slave node buffer capacitor, CVS_S, is not a dominant factor. The capacitor must provide sufficient charge reserve to power the slave node during a LIN frame data packet (LIN signal is periodically asserted low) and also receive a full charge between LIN frame data transmissions (the LIN signal is pulled up to system supply voltage),” Atmel engineering rep Darius Rydahl told Bits & Pieces.

“In practice, bench tests indicate that a buffer capacitor of 47μF to 100μF is sufficient to maintain power to the slave node for a network operating at a data rate of 19.2kbaud with a 100ms delay (or greater) between LIN data frames and a 9V minimum operating battery voltage.”

In terms of the LIN Bus Data Protocol, Rydahl notes that the format of the LIN bus data protocol will affect the charge/discharge rate of the slave node supply line buffer capacitor. Three (primary) factors affect the data format: Rate of data transfer, quantity of data transferred and LIN data schedule table period.

“The LIN bus data rate should be kept high, i.e., a maximum baud rate of 19.2kHz or higher to maximize the speed at which the data can be transferred. The quantity of data number of bits) should be kept as low as possible in order to minimize the duration of the dominant state (logic level low) on the LIN bus line,” he continued.

“And finally, the LIN schedule table period should be long enough in duration to allow the LIN bus powered slave node time to fully recharge the buffer capacitor, CVS_S, between LIN message frames. It should also be noted that most Atmel LIN transceivers are capable of baud rates in excess of the LIN specification.”

On the multi-slave evaluation network side, the two-wire LIN network used for test and characterization purposes is illustrated in figure 8. Essentially, the two-wire LIN network total node count is limited only by the LIN master pull-up resistor’s ability to source the required current to the attached slave nodes to maintain normal operation (slave node VS greater than 5.5V).

“Each node has been configured using the Atmel ATA6617-EK evaluation board (SiP: AVR MCU, ATtiny167 and Atmel SBC ATA6624),” said Rydahl. “This configuration provides one possible operating scenario and, as such, will most likely need to be modified to accommodate the end user’s application.”

The network utilizes the standard LIN protocol and does not deviate from the LIN2.x standard in any manner. The schedule table has been optimized for the two-wire LIN application where a LIN wake-up frame is followed by a single slave node frame shown in figure 9.

“Standard LIN protocol dictates that each node must process every incoming frame ID message on the bus. This forces each slave node to wake-up on every incoming message, regardless of ownership. Sending a wake-up frame followed by a single slave node frame minimizes the time that each slave node is powered ON,” he added.

“The alternate approach of sending a wake-up frame followed by a sequential burst of all the slave frames will cause slave nodes to remain awake longer than necessary. The end result is an overall increase in system load current—a scenario that should be avoided.”

Interested in learning more about Two-Wire LIN networking with Atmel? Be sure to check out part one and two of this series. Part four will run tomorrow.

Transforming LIN Networking Topology to Two-Wire Implementation

By Darius Rydahl

Automobiles now contain hundreds of sensors to measure and report on parameters including temperature and pressure. Most of the time, these sensors are remotely located within a vehicle, far from the host microcontroller that monitors and processes sensor data. Typically, these sensors don’t connect directly to a CAN or LIN network because of the vehicle wiring overhead that’s associated with connecting to the network. However, to overcome this wiring limitation and to reduce required battery supplies, you can convert the standard three-wire LIN network to a two-wire implementation where the LIN slave nodes harvest power directly from the LIN bus master communication wire.

This proposed two-wire LIN configuration eliminates the need for an independent slave node battery supply line.

To successfully implement a two-wire LIN network, the slave node must be supplied with sufficient power to maintain communication at a minimum system operating voltage, typically 9V. Some key parameters affecting slave node performance in this type of implementation include:

• LIN bus power supply—meet a minimum operating voltage threshold  and reduce the pull-up resistor to the smallest value possible (without exceeding the current limitation specification of the LIN driver)
• Slave node current consumption—reduce current consumption by using the lowest clock frequency that enables your application to meet functional design requirements, applying duty-cycling between low and high current operating modes and lengthening the LIN schedule table period
• Slave node buffer capacitance—the capacitor must provide sufficient charge reserve to power the slave node during a LIN frame data packet and to receive a full charge between LIN frame data transmissions. Bench tests reveal that a buffer capacitor of 47µF to 100µF is enough to maintain power to the slave node for a network operating at 19.2kbaud with a 100ms delay between LIN data frames and a 9V minimum operating battery voltage.
• LIN bus data protocol—keep the LIN bus data rate high, at least 19.2kHz, to maximize the data transfer speed. Keep the quantity of data as low as possible to minimize the duration of the dominant state on the LIN bus line. Maintain a LIN schedule table period that’s long enough for the LIN bus powered slave node to fully recharge the buffer capacitor, C_{VS_S}, between LIN message frames.

A two-wire LIN network is ideal for low-node count networks where the system is limited to one master and no more than three slaves, where all nodes are powered on simultaneously. The two-wire network can be easily implemented with a thorough understanding of the system supply/load requirements as well as some hardware modifications.

For more details, read my two-wire LIN networking article.