PID Class Implementation

The PID class provides a wrapper around the Arduino PID_v1 library. This issue outlines the work needed to complete functionality, improve maintainability, and ensure correct behavior across the device.

Goals

• Fully validate and refine PID functionality provided by PID_TC.
• Ensure proper handling of tunings, modes, and computation flow.
• Confirm compatibility with the Arduino PID_v1 library and target MCU constraints (e.g., 4-byte double on Mega2560).
• Review singleton implementation details for correctness and safety.

Reference: PID_TC Public Operations

computeOutput()
getKd()
getKi()
getKp()
getMode()
logToSerial()
setKd()
setKi()
setKp()
setTunings()

Singleton lifecycle:

instance()
reset()

Internal/Private Components for Review

• Constructor / destructor correctness
• input, output, and set_point variable handling
• PID window size management (WINDOW_SIZE)
• Proper initialization and ownership of the PID* pPID instance
• Type limitations on AVR (double being 4 bytes) and impact on tuning precision

Additional Items for Refinement

• Ensure computeOutput() correctly updates input, set_point, and output before/after PID calculation
• Validate PID mode transitions (Automatic vs. Manual)
• Evaluate logging strategy in logToSerial()
• Confirm singleton memory handling and test behavior (reset() vs. destructor)

Start with the PID_TC public operations and its PID_v1 integration, then trace computeOutput(), tuning and mode methods, and the instance()/reset() lifecycle. Review the constructor, destructor, PID* ownership, window sizing, and AVR numeric constraints. Done means the listed operations and singleton lifecycle are validated across the stated modes, calculations, memory behavior, and target MCU constraints.