Testing the PPMScope
Testing the analog signal conditioning stage
First, wire the circuit below, and connect the center of the potentiometer to both Channel 1 and Channel 2 inputs (labeled Ch1_In and Ch2_In on the schematic) on the oscilloscope. You will need a Voltmeter to measure the DC voltage applied on the inputs as well as in various positions in the analog signal conditioning stage.
Make sure the coupling switch is in the AC position and the gain switch is in the 1X position. Now, sweep the inputs from +12 Volts to -12 Volts using the potentiometer. Pins 1 and 7 on U3 should follow the inputs up to -10 Volts to +10 Volts. Pins 1 and 7 on U4 should remain at 0 Volts (perhaps drifting off zero as you turn the potentiometer). Pins 1 and 7 on U5 should be have around 2.5 Volts on them. If they do not, adjust the position of R24 until the voltage is 2.5 Volts.
Next, set the coupling switch in the DC position and leave the gain switch in the 1X position. Again, sweep the inputs from +12 Volts to -12 Volts using the potentiometer. This time, Pins 1 and 7 on U4 should follow the negative of the input voltage. Pins 1 and 7 on U5 should sweep from +5 to 0 Volts.
Next, sweep the potentiometer so that the Channel 1 and Channel 2 inputs are at 1 Volt. Pins 1 and 7 on U4 should read -0.256 Volts. Set the gain switch to the 2X position. Pins 1 and 7 on U4 should read -0.512 Volts. Set the gain switch to the 5X position. Pins 1 and 7 on U4 should read -1.280 Volts.
Testing the digital interface and connecting with the PC
Connect the PPMScope to the PC. Start the PPMScope program, and on the main menu click Configure and then Hardware. The window pictured below will show up.
Parallel Port Setup
2. From the Configuration->Hardware Dialog, you can select Custom LPT Port and then type the address in manually as a HEX number (e.g. 0x0378 is the default address for LPT1).
To test the Parallel Port connections, click the Pin Test Enabled checkbox. With the device installed, toggle the Data signal high and low. You should see a corresponding high and low in the state column for the Data signal and the Data In signal. Also, toggling the Clock signal should produce a corresponding high and low in the state column. If you get bored, you should observe a corresponding voltage transition on the microcontroller pins using a Voltmeter. Close the hardware dialog by clicking OK and the hardware will be configured.
Serial Port Setup
USB Communication Setup
From the main menu, select Configure and then Hardware Test. The Hardware Test Dialog will send a test configuration message to the oscilloscope and give you a transcript of the communications for troubleshooting.
Capturing your first waveform
Hold your breath. Make sure the trigger is turned off. Press the play button on the toolbar. If the program is communicating properly, the circle in the lower left corner should turn green and the screen should display the voltage at the input. If you've left the inputs connected to the potentiometer, you should be able to see the voltage level at the input change as you turn it.
Testing with a signal generator
Now for the fun part! You can test the oscilloscope with a function generator or by constructing a 555 timer circuit or other oscillator circuit. My personal favorite oscillator generates both a triangle and square wave. The schematic is below:
Testing trigger modes
Connect a triangle waveform to Channel 1. Place the trigger mode into a positive slope trigger. As you sweep the trigger level, you should see a corresponding change in the phase shift of the triangle waveform. Similarly, as you adjust the trigger delay and trigger slope, you should see a corresponding change in the phase shift of the triangle waveform.
Testing gains and coupling indication
You should see the position of the gain switches and the coupling updated on the screen at the bottom of the channel information.