More advanced Raspberry Pi Pico (rp2040) Scope and Logic Analzes functions.

While the rp2040 processors are nothing special (ESP-32 benchmarks are faster) the PIO circuits, programmed a bit like FPGAs, can offload timing critical functions from the processors. Applications of the original logic analyzer sample code can sample a signal at 125 Mega samples per second (more with overclocking).  Those $8 analysers' 16 MSPS are just OK for ancient Arduino chips.

An aside:

       Eben Upton notes the complementary capabilities of the rp2040 and the PIO vs the Linux Pi's:

       Has better "deterministic latency" vs the big Pi.  ( chip design cost: £3–4 million )

     ( First of a 12 video series on programming the rp2040 PIO )

The first generation of example projects capture data to a .csv file to be read by the Sigrok PulseView waveform analysis application, this workflow didn't quite suite me. (I briefly glanced at the ideal of emulating one of the devices that already has a sigrok driver)

A hackster.io wite-up of the original 'save to csv' approach: (Google cache shows their complete content)

Using a Raspberry Pi Pico as a Logic Analyzer with PulseView

Raspberry Pi Forum Discussions


Two second generation examples:

 

            This HackaDay article discusses a new Pulseview driver that communicates with the rp2040.


 Specs show:  21 digital channels with up to 120 MHz capture speed, 3 ADC channels at up to 500 KHz, and hardware-based triggers.  It's recommended to add current limiting resistors to help the rp2040 survive slightly out of range voltages.  A logic level shifting chip should be an easy addition for examining 5V signals.

Compiling the sigrok driver is not trivial, the author apparently is waiting for sigrok to add it to their easy to use driver library. (I will be waiting for that)

(I would line to make a compact Dongle-like Logic Analyzer using the tiny (20x17.5mm) Seeed XIAO RP2040. I believe it it provides 8 contiguous ports allowing the PIO to read 8 inputs simultaneously in a byte.) $5.40 when Digikey has stock.



 

Here's an introduction to using PulseView with cheap Chinese box

Using the (Cheap) USB Logic Analyzer with sigrok PulseView
 


- - - - - - - 

 

Scoopy

If you just want to put together a quick box without messing around with code, there is a clever oscilloscope application that uses an Arduino phone to display the waveform.  The Pi Pico code comes in an up-loadable binary, there is a small $3 in app purchase required to enable all? of the app. capabilities.

Specs are mediocre: capturing a maximum of 100 kpts at a speed of 500 kS/s on 2 channels

HackaDay Scoopy write-up: Raspberry Pi Pico Oscilloscope

Binary Pi Pico Source Code  -  Docs  -  Pre-compiled Uf2 binary here

Google Play:  Scoppy - Oscilloscope and Logic Analyzer
 Using the Android App.

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