Error Code Catalog
Catalog of common DRC issues with causes, severity, and fix patterns for fast troubleshooting.
This page is a quick-reference catalog of the most common Design Rule Check (DRC) issues you will encounter in Protoboard. For each issue you will find its severity, what causes it, and how to fix it.
Connection Errors
Protocol Type Mismatch
Severity
Error
State
INCOMPATIBLE
Description
Two interfaces are linked but their protocol.type values do not match.
Common Cause
Manually linking an I2C interface to an SPI interface, or using a custom protocol name that does not match the other part.
Fix
Remove the link and connect interfaces with matching protocol types. If the parts should be compatible, check whether one of them uses a non-standard protocol name (e.g., "serial" instead of "uart") and update the definition.
Role Incompatibility
Severity
Error
State
INCOMPATIBLE
Description
Both sides of the link have the same role (e.g., both master) or roles that are not a recognized compatible pair.
Common Cause
Connecting two microcontrollers via I2C where both are defined as master, or connecting two sensors that are both slave.
Fix
One side must play the complementary role. For I2C, one part must be master and the other slave. For power, one must be output and the other input. Check the role compatibility table for valid pairings.
Voltage Domain Mismatch
Severity
Error
State
INCOMPATIBLE
Description
The interface has requires_matching_voltage_domain: true but the power domains on each side have non-overlapping voltage ranges.
Common Cause
Connecting a 3.3V-only sensor directly to a 12V logic output without level shifting.
Fix
Either add a level shifter between the parts, power the sensor from a compatible voltage rail, or verify that the part definition's power domain ranges are correct.
Allocation Errors
Missing Resource Allocation
Severity
Error
State
PARTIALLY_CONFIGURED or NOT_CONFIGURED
Description
An interface link exists but one or more required functions have no resource allocated to them.
Common Cause
The harness was created and interfaces were linked, but resource allocation was not completed, either automatically (because no resource provides the needed function) or manually.
Fix
Open the harness detail and allocate resources for each unbound function. If no suitable resource exists, the part definition may be missing a resource with that function name.
Resource Over-Allocation
Severity
Error
State
INCOMPATIBLE
Description
The same resource has been claimed by two or more exclusive interfaces simultaneously.
Common Cause
A pin that serves as both I2C SDA and analog input is allocated to an I2C interface and an analog interface at the same time, but shareable_with does not allow this.
Fix
Deallocate one of the conflicting interfaces and choose a different resource for it. If the resource genuinely supports both uses simultaneously, add shareable_with to the resource's function definitions.
Capacity Exceeded
Severity
Error
State
INCOMPATIBLE
Description
An interface instance has more connections than its max_connections constraint allows.
Common Cause
Connecting 12 I2C slaves to a bus that has max_connections: 8, or daisy-chaining too many devices off a single power output.
Fix
Reduce the number of connections to this interface instance. For I2C, split devices across multiple buses. For power, add additional power outputs or use a distribution board.
Max Instances Exceeded
Severity
Error
State
INCOMPATIBLE
Description
More interface instances have been created than the max_instances field allows.
Common Cause
A microcontroller with max_instances: 1 on its I2C master interface, but the design tries to create two I2C bus connections.
Fix
Reduce the number of instances to the limit, or use a different part that supports more instances of the protocol.
Incomplete Configuration Warnings
Unlinked Interface in Harness
Severity
Warning
State
NOT_CONFIGURED
Description
A harness exists between two parts but contains interface pairs that were discovered as compatible yet have not been linked.
Common Cause
Auto-linking was not triggered, or the user explicitly chose not to link certain interfaces.
Fix
Open the harness and review the available interface pairs. Link any that should be connected, or dismiss the warning if the unlinking is intentional.
Incomplete Function Linking
Severity
Warning
State
PARTIALLY_CONFIGURED
Description
An interface link is active but not all of its required functions have been allocated to resources.
Common Cause
An SPI interface requires MOSI, MISO, SCK, and SS, but only three of the four have been allocated, perhaps because the SS pin is already claimed by another interface.
Fix
Complete the allocation by assigning resources to the remaining functions. If the needed resource is already taken, resolve the conflict first.
Unconnected Part
Severity
Warning
State
N/A (part-level)
Description
A part is placed on the canvas but has no harnesses connecting it to any other part.
Common Cause
The part was placed for planning purposes but has not been wired yet, or a harness was accidentally deleted.
Fix
Connect the part to the relevant parts in your design, or remove it if it was placed in error.
Design Rule Violations
Part Design Rule Triggered
Severity
Warning (may escalate to Error for safety-critical rules)
State
N/A (part-level)
Description
A rule from the part's design_rules array is flagged based on the current configuration.
Examples
"Maximum 40mA per I/O pin" when a high-draw device is connected to a GPIO. "VIN must be 7-12V when using external power" when the supply voltage range does not overlap.
Fix
Review the design rule text and adjust your design accordingly. These rules come from the part's datasheet and represent real hardware limitations.
Power Budget Exceeded
Severity
Error
State
N/A (part-level or board-level)
Description
The total current draw from a power domain or power output exceeds its max_current_mA rating.
Common Cause
Too many high-draw devices connected to a single regulated output (e.g., 6 servos on a 500 mA 5V rail).
Fix
Reduce the load, add an external power supply, or use a power distribution board. Check each connected device's current requirements and ensure the sum stays within budget.
Quick Diagnosis Table
Red edge on canvas
INCOMPATIBLE link: protocol, role, or constraint mismatch
Board Review > Errors
Yellow edge on canvas
PARTIALLY_CONFIGURED: incomplete allocation
Harness detail panel
Gray edge on canvas
NOT_CONFIGURED: no allocation performed
Harness detail panel
Part has error badge
Design rule or power budget violation
Board Review > By Part
"No compatible interfaces" message
Protocol or role mismatch between parts
Check both part definitions
Auto-link did not fire
Resources unavailable or already allocated
Check resource utilization
Troubleshooting Checklist
Check role compatibility
Roles must form a recognized pair. Use the compatibility table to verify.
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