1st Place Winner:
MultiFunctionTool, Jingxi Zhang, U.S.A.

Download the full project abstract

Our congratulations go to Jingxi Zhang, the 1st place winner. Mr. Zhang took the feature set of the LM3S811 nicely through its paces, utilizing the ADC, SSI, analog comparator, I2C and PWM functionality. It operates as a handheld device and plugs into a PC to display graphics-rich functionality.

The Handheld Multifunction Scope can be operated in standalone mode with three AAA batteries. It can also be powered through a PC USB port, and in this mode, the PC screen is used to show the oscilloscope display and the measurement values. Zhang's flexible tool functions as a dual channel trace oscilloscope; an AC/DC Voltmeter, Ohmmeter, capacitance, and inductance meters; frequency counter; a logic probe; and a pulse generator.

The MultiFunction Scope showcases many of the built-in features of the Stellaris LM3S811.

• The fast on-chip analog-to-digital converter (ADC) is used with an external signal condition circuit to sample the dual channel signal. The ADC is used for the oscilloscope, voltmeter and ohmmeter.
• The ADC also samples the voltage output of the potentiometer on the evaluation board. The output of the potentiometer is used as the oscilloscope trigger level as well as the frequency and duty cycle adjustment of the pulse generator.
• The on-chip SPI controller (from SSI interface) controls the gain of the external dual channel amplifiers. One of the on-chip timers (Timer 2A) is used to measure the capacitor and inductor values with a couple of external resistors.
• The on-chip analog comparator is used to threshold the small signal for the frequency counter. The comparator output is then sent to a timer for counting the frequency.
• The on-chip analog comparator is also used for the logic probe to detect open circuit or high impedance tri-state.
• The on-chip I2C controller is being used to output data to the OLED display. All modes send the output to the OLED display. GPIO pins with the interrupt enabled are used to detect the function mode selected by the mechanical slide switches.
• A Pulse Width Modulation (PWM) interface is used to output the pulse in pulse generator mode. The frequency and duty cycle can be easily setting the PWM registers.

To reduce the number of buttons for operating different functions, a thumbwheel rotary encoder with a push-in button is used. The user can use the thumbwheel to select an item from a menu shown on the OLED display and activate a function.

The device can also send the measurement data to a PC though the on-chip fast UART interface. The serial port of the UART is carried by the on-evaluation-board USB controller to PC. A Windows application written in the C# language displays the scope traces and other meter readouts on the PC's display output.