I understand the DSO nano project originated as an open source effort. Unfortunately these contributions appear to have been offered by individuals with limited programming skills and even with the most recent 2.5e version we’re not much further than a pretty enclosure with potential. All in all the DSO is not useful other than for a few basic tasks.
A proper digital scope will need a three phase approach to sampling. That is pre-fetch, trigger phase and post fetch. The trigger phase must last until a trigger is found (forever if need be) while the sampling buffer is continually reused in a round-robin fashion (no samples must be lost or disregarded in this phase). When a trigger condition is met, post fetch will start and at the end all sampled data will be presented with the trigger point centered on the display. Unfortunately this is not the way 2.5e and prior versions work. The approach taken with the DSO Nano is the simplistic single buffer capture followed by trigger search. This makes it more or less useless for digital analysis (e.g. SPI, I2C, serial) and also of limited use for signals like electronic ignition (narrow, infrequent pulses) and many (if not most) other real life measuring and fault finding challenges.
Thanks to SeedStudio however, the current software is open source and based on the most recent 2.5e source release I’ve rewritten it to fix the more fundamental issues. This includes the following fixes:
• Proper three phase sampling (pre-fetch, trigger-fetch, post-fetch) guaranteed never to miss infrequent events
• More efficient screen update (10-100 times faster than current version)
• Eliminate all flickering and stuck pixels
• Code is re-written to allow full compile time optimization (much faster and compact code all over)
• A bug in Vrms calculation is fixed (Vrms is incorrect in 2.5e)
• A number of overflow bugs have been fixed (calculations for large time/div settings)
• Scan has been replaced with a proper continues real-time scan mode
• Configuration can be saved to /restored from SD card or flash (default power on settings).
• Wave data (reference signals) can be saved/restored from SD
• Screen capture can be saved to SD files
• A number of issues with incorrect SD file handling in 2.5e have been fixed
• FIT mode is implemented as a function
• A captured signal can be panned left right for further inspection
• A more relevant collection of data is selected for display on screen
• A more relevant selection of measurements
• Use proper ISO abbreviations (e.g. milliseconds is “ms” not “mS”)
• A completely redesigned user interface (no annoying blinking or color abuse)
All menu items are available from the right hand side of the display. These are organized in the following groups:
VD - Voltage/Div
TD - Time/Div
YA - Y-axis options
XA - X-axis options
TR - Trigger options
ME - Measurements
FI - File options
FR - Frequency out
OT - Other
Use arrow up/down to move between groups. Moving past upper/lower wraps around to other side. Within each group there are one or more sub-commands. As an example YA (Y-axis) have sub commands for V1 Cursor, V2 Cursor and Gnd position. Use the “M” button to display a popup window with supported sub-commands, up-down to change selection and M to close the popup.
Use left/right to change the setting of the active command within the currently selected group. Use either the B button (new version of Nano) or a long press of M to show/hide cursors or save/load files.
Choose Trigger Mode (in TR group) and press B (or long M) to activate the FIT function.
Choose Time/Div greater or equal to 100ms to activate real.-time scan mode (use Auto trigger for test).
For those who want to try the extended and updated version, you need to upload the attached version (use together with LIB version 2.2).
Most of the time when changing time/div the waveform disappears and it doesn’t look like a drawing bug because the frequency counter changes to “freq” too. The freq popup shows --.- or something like that. And I can’t get rid of that reference waveform 