Source: https://mokxi.com/docs/editor/logic-analyzer Updated: 2026-11-08 The editor # The logic analyzer tab Capture the digital edges on four probes, trigger on an edge or a pattern, decode UART, I2C, SPI, 1-Wire and WS2812, and export the capture. Open the editor All the docs ### Contents Start here The editor The sidebar and the editor's pages Placing parts Wiring Sticky notes Drawing on the canvas Tidying up Pinned comments Frames Schematic view PCB view Reusable blocks Chips made from parts Custom chips written in C The code editor and compiling Writing assembly Show an image on a MicroPython display Run and the serial monitor The serial plotter Operating point, sweeps and frequency response The logic analyzer tab The debugger Mokxi AI, Mokxi's helper The AI Builder WiFi, simulated Real internet Blynk, simulated Bluetooth, simulated ESP-NOW between boards The properties panel Undo, copy and paste Keyboard shortcuts Customize: code themes, colors and the toolbar Saving and autosave Sharing a project Embedding a circuit on another site Export and download Send a program to a real board VS Code and GitHub with Mokxi Run a prebuilt firmware SPICE netlists in Mokxi Working on a phone Install it as an app Boards Parts Accounts and plans Live collaboration Classrooms Lessons and the learning game Hobby builds Troubleshooting Reference Docs / The editor / The logic analyzer tab Mokxi team ยท The editor The logic analyzer part on the canvas is the instrument: four probes, D0 to D3, and a ground clip. Its face shows the newest few milliseconds. The Logic tab is the bench analyzer behind it, full size, with a trigger, protocol decoders and files you can open in PulseView, GTKWave or a spreadsheet. The part itself, its face and its properties are in the logic analyzer. ## Capture a signal - Add a logic analyzer from the parts panel and clip D0 to D3 to the nets you want to watch. Wire its ground clip to the circuit's ground. - Press Run. - Press Logic in the bar above the serial monitor. On a phone it is under More in the bottom sheet. - Press Start. With no trigger set, the capture starts at once. Press Stop to end it. With more than one analyzer in the circuit, a list at the top picks which one the tab reads. ## Channels One row per probe: a box to show or hide the trace, its color, a name of your own (SCL reads better than D0), and the net it is wired to, or not connected. The names carry through to the trigger, the decoders and the exported files. ## Trigger Trigger chooses when a capture starts: - None (start now): as soon as you press Start. - Rising edge, Falling edge or Either edge on the channel you pick under On. - Pattern: each channel set to X (any), 0 or 1, and the capture starts when all four match. Before, ms keeps that much from before the trigger, and After, ms how much to capture after it. Mode is Repeat, which arms again as soon as a capture ends, or Single, which stops after one. Edge limit fixes the memory when the capture is armed: 64 k, 256 k or 1 M edges. It never grows however long the circuit runs, and a capture that hits it says it was cut short. The status line under the screen says what the analyzer is doing: waiting for the trigger, capturing, or stopped, with how much time and how many edges the capture holds. ## Decoders Add a decoder offers UART, I2C, SPI, 1-Wire and WS2812 (NeoPixel). Each one is drawn as rows of labels under the traces and listed in a Decoded table of time, row and value. Decoder You set UART RX and TX channels, Auto baud or a Baud, Inverted, a Spike filter I2C SCL and SDA, a Spike filter SPI SCK, MOSI, MISO, CS, the Mode (0 to 3), bit Order, Word bits, CS active high 1-Wire the Line WS2812 the Data in channel and its timing Remove takes a decoder off. The table shows the first rows of a long capture; the Decoded (CSV) file has them all. ## Reading the screen Wheel or pinch to zoom and drag to pan, or use the -, + and Fit buttons. From the keyboard, with the screen focused: Key Does Arrow keys pan + and - zoom Home show the whole capture T go to the trigger [ and ] step the cursor from edge to edge , and . step through the decoded rows The screen is drawn a pixel column at a time, so a capture of a million edges costs no more to look at than one of a hundred. A column with several edges in it shows as a block of activity until you zoom in. ## Export Four buttons take the capture out: - VCD, for GTKWave and most waveform viewers; - sigrok (.sr), a session for PulseView; - Edges (CSV), one row per change; - Decoded (CSV), every decoded row. The same files are in the editor's Export menu while the tab holds a capture. ## What is saved Nothing in this tab is saved with the circuit: a trigger is how you look, not part of what you built. Your setup for each analyzer is remembered in this browser for the next visit. The window and the decode setting on the part's face are properties, and those are saved with the circuit. ## If it does not work - No logic analyzer in this circuit. The tab says so until one is on the canvas. - Start is grayed out. There is no analyzer in the circuit to read. - The capture never starts. The trigger has not happened. Check the channel under On, or set the trigger to None (start now). - A channel is drawn down the middle. Its probe is on a net nothing drives, or on nothing at all. - A decoder shows nothing. Check that its channels match the probes, and for UART that the baud rate is right, or tick Auto baud. ## Related - The logic analyzer part - The oscilloscope, for a waveform rather than a sequence - The bench instruments - Operating point, sweeps and frequency response - The serial plotter Previous: Operating point, sweeps and frequency response Next: The debugger ### On this page Capture a signal Channels Trigger Decoders Reading the screen Export What is saved If it does not work Related ### Other guides The debugger Stop a board on a line of your own code, look at what it was doing, and step through it while the circuit stays exactly where the halt found it. Mokxi AI, Mokxi's helper Mokxi AI answers questions about your circuit and code, explains build errors, and fixes them with a change that compiles first. The AI Builder Describe a project in your own words and Mokxi AI picks the parts, wires them, writes the code and tests it before it opens.