modelLogicAnalyzer

Information

Probe of a logic analyser: connect its channels CH0…CH7 to lines of the circuit (a UART link, the SCL/SDA lines of an I2C bus, the clock and data lines of an HX711, a PWM output...) and its GND to the ground of the circuit, as with the clips of a real analyser (or uncheck useGroundPin, "Electrical" tab: the pin disappears and the probe is referenced to the simulation ground, 0 V). Each channel has a very high input impedance (GIn, 1 GΩ to ground): the circuit behaves the same with or without the probe.

Each channel has its own tab (CH0…CH7): a name and a kind (Interfaces.ChannelKind):

• Off: not recorded, costs nothing, and its pin disappears from the icon. By default, CH0…CH3 are Logic and CH4…CH7 are Off: give a kind to a channel to make its pin appear. The names of the active channels are shown in green on the icon;
• Logic: logic level only — also the kind of a clock line;
• Uart: serial link decoded with the format of the tab (speed, data bits, parity, stop bits, bit order);
• I2cSda: SDA line of an I2C bus, whose SCL line is the channel clockChannel;
• SyncData: data of a synchronous serial link (HX711, simplified SPI), read on an edge of the channel clockChannel, in words of wordBits bits.

At the end of the simulation, the probe writes in the simulation folder, named after the component unless fileName is given (full paths in the log):

• a text file (writeText), opened in Notepad if openText is set: the decoded bytes of each channel in hexadecimal + ASCII (UART bursts, I2C transactions, synchronous words, summary of the logic channels), then an ASCII timing diagram of the channels, with the bits and bytes under each decoded waveform. The "Text file" tab chooses the sections, the frames on separate lines, the silences not drawn, the resolution and the width;
• a VCD file (writeVcd, Value Change Dump), opened in PulseView (free software of the sigrok project, with its own protocol decoders) if openPulseView is set; GTKWave also reads it. Next to it, a PulseView session (writePulseViewSession, <base>.pvs) that PulseView loads by itself with the VCD file: its UART, I2C and SPI decoders are already set up from the channels (a SyncData channel is decoded as SPI).

With pulseViewPath empty (the default), the probe looks for PulseView in this order: the environment variable MICROPYTHONMCU_PULSEVIEW (path of pulseview.exe or of its folder, e.g. a copy on a network share), the portable copy fetched by get_pulseview.cmd into the PulseView folder next to the library, then the folder of the sigrok installer (C:/Program Files/sigrok/PulseView).

A level change is detected halfway between VIL and VIH; a level that changes and changes back at the same simulated instant is not recorded. Cost: one threshold-crossing function per channel that is not Off; on lines that already change at events of the model (outputs of the microcontroller or of a device), the probe adds no event of its own. The text file is written from the level changes kept in memory, without any extra event.

Parameters

Connectors