Troubleshooting Guide #

Solutions to the most common problems in Breadpad.

Simulation won’t run #

“No DC path to ground” #

Every node needs a DC path to the ground reference.

• Connect your voltage source’s negative terminal to ground.
• Make sure no node is left floating.
• Add a high-value resistor (e.g. 1 GΩ) from a floating node to ground.
• If a capacitor blocks every DC path around a node, add a parallel resistor.

No source #

SPICE needs at least one source. Add a voltage source, make sure it’s connected, and check its value isn’t 0 V. AC analysis needs an AC source.

Nothing is connected #

Components must be electrically connected. Use the Wire tool to join terminals, and check that wires land on the intended tie points.

Convergence failures #

“Timestep too small” or “Convergence failed” means the solver can’t find a stable solution. Common causes and fixes:

• Ideal sources in a loop — add a small series resistor (e.g. 0.01 Ω).
• Unrealistic values — avoid exact 0 Ω or infinite values; use small finite ones (0.001 Ω, 1 fF).
• Pure inductors — add a little series resistance.
• Capacitor-only nodes — add a large parallel resistor for a DC path.

Debug by halving the problem: remove reactive components and use DC sources first; if that converges, add components back one at a time until the culprit appears, then add series/parallel resistance or fix its value.

For finer control, use the SPICE Shell to set ngspice options:

.options reltol=0.01
.options abstol=1n
.options itl1=300

Component placement #

A component won’t place if it would overlap an existing chip, voltage source, or transmission line, or if its tie points are out of bounds. Move it to a clear area. If a component seems to vanish, it was likely deleted — undo with ⌘Z (or shake-to-undo on iPhone).

Editing values #

Tap a placed component to open its editor. If a parameter is greyed out, it’s a Premium parameter (e.g. tolerance, TC1/TC2). See Pricing.

Performance #

If simulation is slow: shorten the transient time window, reduce the number of probes, simplify the circuit, or use a coarser time step. Restarting the app and freeing storage can help if the app feels sluggish.

Results don’t match expectations #

• Check values and prefixes — 10k vs 10M is a 1000× error.
• Check the model — default device models may differ from a specific part.
• Check probe placement — confirm you’re measuring the intended node.
• Check the analysis mode — Operating Point ignores reactive dynamics; use Transient for time-domain behavior and AC for frequency response.

File & sync #

Circuits sync through iCloud Drive when every device uses the same Apple ID with iCloud Drive enabled. If changes aren’t syncing, confirm that setup, give it a moment, and check your iCloud storage quota.

Importing netlists #

Breadpad imports SPICE3-compatible netlists (.spice, .cir). If an import fails, remove vendor-specific or unsupported directives, make sure every .model/.subckt is defined before it’s used, and simplify the netlist to isolate the problem.

Common error messages #

Gamepad #

See Gamepad Troubleshooting.

Still stuck? #

Report it from the app: Settings → Send Feedback. Include your device and OS version, the steps to reproduce, and the exact error text.