SD Class Implementation

The SD class currently provides a partial interface for SD card operations. This issue tracks the work needed to fully implement and validate the SD storage functionality used across the device.

Goals

• Expand the SD class to include complete, reliable SD card interaction features.
• Review all methods defined in SD_TC (C++ implementation) and determine which should be included or updated.
• Confirm compatibility with the target hardware environment and the SdFat library.

Reference: SD_TC Public Operations (from header file)

writeToDataLog()
appendToLog()
countFiles()
exists()
format()
getRemoteLogContents()
listRootToBuffer()
mkdir()
open()
printRootDirectory()
remove()
todaysDataFileName()
writeToRemoteLog()

Internal/Private Helper Methods

- appendStringToPath()
- iterateOnFiles()
- updateRemoteFileSize()
- incrementFileCount()
- listFile()

Additional Items for Review & Refinement

• File-stack depth management (MAX_DEPTH)
• Buffer management for file listing and log retrieval
• Use of PROGMEM for remoteFileName
• Error-state tracking via hasHadError
• Proper singleton lifecycle management (instance() / deleteInstance())

Start by comparing the partial SD class with the SD_TC C++ implementation and its listed public and private operations. Review the SdFat usage, MAX_DEPTH, buffers, PROGMEM handling, error tracking, and singleton lifecycle against the target Raspberry Pi Pico environment. Done means the required operations are implemented or updated and the SD functionality is validated for hardware compatibility.