PPMScope is a do-it-yourself oscilloscope design with a maximum sample rate of 1 MHz (bandwidth of 500 kHz).
The hardware is based on the PIC16F877A
Microcontroller. I am creating this
tool for my general use at home, but I thought others may benefit from
the software and schematics. The hardware design
includes a 50 Watt power supply (+12,-12,+5 Volts). I will later add a
function generator (sine, triangle, square) to my scope. The function
generator will be an analog generator with a 50 ohm output
impedance.
The human interface to the oscilloscope is both a part of
the box (knobs, switches, etc) and through a PC program
written in C for Windows.
The scope interfaces with the PC and communicates with the Windows software to
display the captured waveform in the both the time and frequency domains.
The design combines a high frequency analog stage with AC/DC coupling and three gains, a
MAX118 digital to analog converter, a trigger circuit, a PIC16F877A microcontroller, and
some PC interfacing hardware. The oscilloscope specifications are in the table below:
Specifications and Goal Feature List:
Current Version (v.2.01)
Goal Version
Sample Rate
Variable, single shot 1 MHz max, interlaced 151 kHz max
Variable, single shot max 1 MHz, interlaced max 417 kHz, repetitive 5 MHz
Bandwidth
500 kHz
500 kHz
Number of Channels
Two
Two
Sample Depth
256 bytes per channel, 128 bytes per channel when interlaced
256 bytes per channel, 128 bytes per channel when interlaced
Sample Modes
Single shot and interlaced
Single shot, interlaced channel, and repetitive
Calibration
Voltage offset
Voltage per division and voltage offset calibration
Configuration Settings
Configuration of default and saving of settings for future use
Configuration of default and saving of settings for future use
Hardware Connection
Any parallel port
Any parallel, serial, or USB port
Coupling
AC and DC, reflected on PC
AC and DC, reflected on PC
Channel gain
Gain of 1, 2, and 5, reflected on PC
Gain of 1, 2, and 5, reflected on PC
Trigger
Variable level, slope, and timing
Variable level, slope, and timing
Frequency Spectrum
Yes
Yes
Waveform Reconstruction
Triangle, square, point, and sinc
Triangle, square, point, and sinc
XY view
Yes
Yes
Channel offset and volt per division settings
Yes
Yes
Cursors
Yes
Yes
Math functions
Only addition and subtraction of channels
Addition, subtraction, auto period, auto peak-to-peak, etc.
Waveform export
Comma delimited
Bitmap and comma delimited
Files for download:
PPM Scope for Windows version 2.01
Beta version of a DIY (do it yourself) oscilloscope with a maximum sample rate of 1 MHz.
For development news, please see the comment/development log.
Click here to send me comments or suggestions.
PPM Scope - 1 MHz (for DOS) -- DEPRECIATED
This version of the digital Oscilloscope is a work still in
progress. The
Oscilloscope has a bandwidth of 500 kHz and a maximum
sample
rate of 1 MHz. The hardware is based on the PIC16F877A
Microcontroller.
The human interface to the oscilloscope is both a part of
the box (knobs, switches, etc) and through a PC program
written in PowerBasic for DOS. The PC program features
cursors, frequency domain representation, optional waveform
reconstruction methodology, single shot and hold modes, X-Y
mode, and various mathematical operations. You will be
able to save
your
data or a picture of your waveform as a bitmap or as a text
file include frequency domain information.
Files for download:
PPM Scope 1 MHz version 0.102a
Alpha version of a DIY (do it yourself) oscilloscope with a maximum sample rate of 1 MHz. No configuration and calibration incorporated into the software. Limited functionality.
This version of the digital Oscilloscope is a preliminary
verion in support of the development of a 1 MHz PC based
digital oscilloscope. The oscilloscope has a bandwidth of
100 kHz and a maximum
sample
rate of 200 kHz. The hardware is based on the PIC16F84A
Microcontroller. The hardware schematic does not include
any signal conditioning or protection for the analog to
digital converter, but represents the minimum hardware
for the PIC to interface with the PC and the ADC. The PC program features
cursors, frequency domain representation, optional waveform
reconstruction methodology, single shot and hold modes, and X-Y
mode. The interface allows control of the trigger timing, the offset, the voltage, and the time scale.
The PC software for the 1 MHz version is compatible with the 200 kHz hardware.
PPM Scope 200 kHz version 0.1a
A development version of the oscilloscope, provided as an archive.
