Scope to Digital – Interpreting Analog Input Signals as Digital Signals

by Arthur Brown

Digilent is introducing the Scope to Digital feature in WaveForms, which allows you to interpret captured analog signals as digital signals when using the Scope instrument’s Digital view. The Scope to Digital feature is supported by all of Digilent’s WaveForms-compatible Test and Measurement devices, from the Analog Discovery through to the Analog Discovery Pro ADP 3000/5000 series and Eclypse Z7.

New WaveForms Feature: Scope to Digital

The Digital View in WaveForms implements many of the same features as the Logic Analyzer, integrating them in with the Scope instrument. All familiar types of signals are supported – single-bit signals, buses, SPI, I2C, and UART interfaces, in addition to many other standard and custom protocols. All the familiar digital trigger functionality, including pulse triggers and protocol triggers (like triggering on), from the Logic Analyzer instrument is supported for true digital inputs. When a digital trigger is used, the analog inputs are automatically set up to trigger at the same time. 

When Using Scope to Digital instead of Digital Inputs?

When enabled, WaveForms application will digitize all enabled analog inputs in software and allow them to be added to the Digital View.

There’s more to it, threshold voltages used to digitize the signals are configurable – meaning that many different logic standards can be supported, potentially even those beyond the normal capability of your device’s digital inputs. This could include CAN signals, 15 V RS-232 signals using the UART protocol, and RS-485 signals, for a few examples. Because thresholds are individually configurable per channel, you can even mix-and-match.

See how to configure logic thresholds by following the red arrow in the image below. Click the “Scope to Digital” button, then set a threshold in the dialog. In this example, we can compare the Scope plot to the Digital plot – only the pulses that exceed the 2 V threshold are digitized as logic “1”.

There’s one important caveat. Because the analog to digital conversion is implemented in software, digitized analog inputs cannot be used for digital triggering. That said, you can always still pass the same signal to both a digital input and an analog input simultaneously as long as that signal is compatible with both of those inputs. Software digitization removes the hassle of wiring up two inputs in situations where you have other trigger sources.

Digilent’s Test & Measurement Devices are available from stock at Elfa Distrelec A/S, the authorized distributor of Digilent in Denmark.