Mock Device for Testing

Overview

The cr-mock tool simulates a CurrentRanger R3 device over a virtual serial port (PTY). It responds to all firmware commands identically and generates configurable current waveforms.

Running

# From the project root
just mock                      # auto-creates PTY, launches TUI
just mock-port /dev/ttyUSB0    # use a specific serial port
just mock-release              # optimized build
just dev-with-mock             # app + mock in tmux split panes

TUI Controls

The mock runs an interactive terminal UI where you can configure the simulated waveform in real-time.

Key	Action
Tab / Shift+Tab	Cycle fields: Waveform, Range, Base, Min, Max
Up/Down	Select waveform or adjust value
Left/Right	Cycle range (mA/uA/nA) or adjust value
Shift+Up/Down	10x larger step for value fields
1-9, 0, a, b	Quick-select waveform by number
q / Ctrl-C	Quit

Waveforms

#	Name	Description
1	Steady DC	Constant value at base
2	Sine Wave	0.5 Hz sine between min and max
3	Pulse	1 Hz, 10% duty cycle
4	Sawtooth	0.5 Hz ramp from min to max
5	Brownian Noise	Random walk within min/max
6	Sleep/Wake	4-second period: 75% at min, 25% at max
7	Random	Uniform random per sample
8	Step Up	Staircase min to max, then reset
9	Step Down	Staircase max to min, then reset
0	Step Ping-Pong	Triangle staircase min-max-min
a	Exp Decay	Exponential decay from max to min
b	Burst	Random short spikes on idle baseline

Parameters

Range (mA/uA/nA): Sets the display units and default step sizes
Base: The center/DC value for steady and noise waveforms
Min: Lower bound for waveforms that sweep a range
Max: Upper bound

How It Works

The mock creates a POSIX pseudo-terminal (PTY) and writes the slave path to /tmp/cr-mock.port. The CurrentRanger app reads this file during port enumeration and adds it to the port list as “CurrentRanger Mock”.

The mock implements the full firmware serial command protocol, including the USB logging bootstrap handshake.