Analog Experiments Anywhere Using Pic

Two DIY micro-controller based USB connected electronic units which along with the Texas Instruments Analog System Lab Starter kit and a laptop permit you to conduct analog experiments anywhere.

It would be wonderful  if senior students and laboratory supervisors built these units so that they could be used in their laboratories by freshers.

Aj-SigGen-PS     http://ajoyraman.in/DDS_SigGen_PS.html

Aj-Simple-Scope      http://ajoyraman.in/USB_Simple_Oscilloscope.html

Analog System Lab Starter Kit ASLKv2010    http://www.uniti.in/teaching-material/analog-system-lab-starter-kit

Step 1: Aj-SigGen-PS

This unit is designed to compliment the Aj-Simple-Scope and serve as a teaching aid for budding engineers, electronic enthusiasts and hobbyists.

This USB connected unit implements a microcontroller based DDS Signal Generator providing Sin and Triangular waveforms with adjustable magnitude and offset up to 50 kHz. TTL and 1 V square waves are simultaneously provided. Additionally ± 12V and a variable +2 to 7V output with a total capacity of  1W is provided to power external circuits under test.

Step 2: Block Schematic and Function Description of Signal Generator and Power Supply Unit

For ease of portability the unit is powered and controlled from the USB port of a PC.

Two PIC18F14K50 microcontrollers are used to provide the functionality of the unit.

The first PIC microcontroller implements the following functions:

• Communicates with the host PC for enumeration as a USB to UART device

• Sets up the unit as a 500mA device

• Switches on power to the DC-DC converter

• Provides the complimentary square wave drive to the DC-DC converter

• Acts as a USB communication interface to the second PIC

• Provides the Amplitude reference for DAC2

• Provides the digital word for DAC1 giving the offset value.

The second PIC microcontroller implements the remaining DDS functions

• Direct Digital Synthesis (DDS) signal generation

• Sin/ triangle word output to DAC2

• TTL and 1 V square reference output

The DC-DC converter is a driven 1W, 5V to ± 12V operating at 100 kHz. The +12 V output is fed to a linear regulator to provide a variable +2 to 7 V output controlled by a variable potentiometer.

The DC-DC converter provides full protection to the host PC USB port as its outputs are short circuit and current limit protected.

The circuit under test can be rigged up on a standard breadboard and powered from the power sockets provided.

Step 3: Aj-Simple-Scope

This unit is designed to compliment the Aj-SigGen-PS and serve as a teaching aid for budding engineers, electronic enthusiasts and hobbyists.

This USB connected unit implements a microcontroller based 2-Channel Oscilloscope providing continuous sampling rates up to 100 ksps and 20 Msps using equivalent time sampling. Common DSO features such as spectrum analysis, waveform capture and data saving are provided. The input range is ± 12V with additional gain settings of X2 and X5. Trigger and sweep options are also provided.

Step 4: Block Schematic and Function Description of the Simple-Scope Unit

 

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