In any vehicle, the instrument cluster forms a critical part as it is the face of the vehicle that reflects the current state. Apart from providing the basic vehicle information, it can also provide crucial indications of electrical component malfunctions (EFI /ISG related). Clusters can acquire vehicle data over simple mechanisms such as encoders as well as through complex interfaces such as CAN, SAEJ1850 etc., Instrument cluster design for electric vehicles may have less system complexity, but they have to be more user friendly, less power hungry, and a cost-effective solution. Careful design and choice of cluster components is necessary to meet the stringent compliance requirements. Of the constituent components, the MCU holds the major stock whereas only a few vendors will be supporting automotive grade with the desired feature sets.

Fuel Gauge: The Fuel gauge ranges from Empty (E) to Full (F). Typically, the Fuel sensor unit is a TSR /SMR type realized with components such as float with potentiometer, Adjustable arm and sending unit with two wires (signal & ground wire). RPM Gauge: The signal received from the RPM sensor from encoder such as tach terminal unit with signal & ground wire, fire wall grommets is treated as frequency input. Based on the type and top speed of the vehicle, the input range varies. Temperature Gauge: The signal received from the temperature sensor is also analog. Realized with sensors such as protective rubber unit, thermistor with two wire. Front end circuit converts the input resistance to corresponding voltage and. Seven Segment Displays: Clusters may have different type of segmented display with various resolutions such as 27 X 4, 39 X 4, 48 X 4, 53 X 4 and 54 X 4. These could indicate information such as odometer, trip distance, hour meter etc.

Microcontroller: The RL78 MCU helps in achieving the highest performance within the low end MCU space. It offers improved efficiency, extensive scalability and reliable safety functions that aid in developing energy efficient instrument clusters. It has an operating voltage that ranges from 2.7V to 5.5V and flashes the program using 80 microcontroller pins. Stepper Motor Drivers: There are up to three channels of stepper motor controllers / drivers with zero-point detection that can be configured using PORT pins (Sin+, Sin-, Cos+, Cos-). Each channel is controlling a stepper motor dedicated to gauges which commands the motor to move and hold at one of the angles without any position sensor. With the help of software based PID control, it is possible to effectively control the needles.

Multiple IOs: There are multiple analogs and digital IOs available for interfacing sensors and Tell-Tale LEDs. RPM, temperature, and fuel level sensors are interfaced via a suitable front-end circuit. If needed, various Tell-Tale LEDs such as turn left, turn right, service, brake, etc. can be driven with dedicated digital outputs.