Low-Cost Gauge of Fuel Consumption

Figure 1 

The project aims to build a cheap gauge that can measure in real-time the fuel consumption of a vehicle.

An inexpensive Atmel 8515 AVR microcontroller is being used by this project for obtain real-time air-flow data and vehicle speed. This is suitable from an engine that uses the J1850 VPW bit-serial bus since the information as a fuel consumption rate in miles per gallon (MPG) is illustrated using the analog display. The display was made with a modified meter faceplate from an off-the-shelf electronic tachometer. The gauge can operate without any special automotive bus interface chips since it only uses a few extra components such as diodes, resistors, capacitors, and transistors.

This design based on a microcontroller can be safely connected to the power supply of the automobile which has 12VDC rating on the battery bus. It tolerates the ground and power supply short circuits as well as reversed battery voltage although it provides a simple and robust connection to the J1850 VPW bus. The functionalities of the J1850 VPW protocol along with the gateway to the real-time data stored in the engine computer are revealed through the use of the embedded C-code.

Rest of the project