DESIGN AND DEVELOPMENT OF LOW-COST HANDHELD OSCILLOSCOPE

Abstract

The paper presents the design and development of a portable and-held digital oscilloscope using Atmel Atmega644p Microcontroller Unit operating at 20MHz & 20MIPS on a mono chrome Graphical Liquid Crystal Display. The oscilloscope has two channels through which the controller samples the analog input signals. AC & DC signals are fed to the controller’s ADC for conversion into its digital equivalents. The sampled signals undergo processes of pre-scaling, filtration, storage, reconstruction and then displayed on the GLCD. The microcontroller is programmed using BASCOM-AVR, a BASIC programming language-based Integrated Development Environment (IDE) The Oscilloscope can display the scaling factor used in readable format in Volts/div for the vertical axis and Time/div for the horizontal axis. It can also display measured signals from the two channels simultaneously and has channels offset control and trigger mode adjusting. The handy Oscilloscope has the capability of displaying the measured signal frequency value in the range of 0-250kHz. Some signal types were measured and compared with the laboratory oscilloscope and produced an error of less than 5%. The cost of the hand-held oscilloscope was N12,410, which is less than $50, hence it is low-cost compared with commercially available digital oscilloscope.

Keywords

• a/d conversion
• atmega644p microcontroller
• oscilloscope
• pre-scaling
• sampling
• transducer