storage

Zephyr Storage

Implement reliable persistent data handling using Zephyr's storage subsystem and flash management utilities.

Core Workflows

1. NVS Storage

Utilize Non-Volatile Storage (NVS) for efficient, wear-leveled data persistence.

• Reference: nvs_storage.md
• Key Tools: nvs_mount(), nvs_read(), nvs_write().

2. Flash Management

Configure and manage flash partitions and hardware page layouts.

• Reference: flash_management.md
• Key Tools: fixed-partitions, FLASH_MAP, flash_get_page_info_by_offs().

Quick Start (NVS Write)

#include <zephyr/storage/nvs/nvs.h>

void save_data(struct nvs_fs *fs, uint16_t id, void *data, size_t len) {
    nvs_write(fs, id, data, len);
}

Professional Patterns (Reliability)

• Settings Integration: Use NVS as the backend for the settings subsystem for a standard key-value configuration experience.
• Collision Prevention: Define NVS Entry IDs in a centralized header file to prevent accidental overwrites across modules.
• Runtime Layout Checks: Always query the flash controller for page sizes (flash_get_page_layout) rather than assuming hardcoded sector sizes.

Automation Tools

• nvs_id_lint.py: Detect duplicate NVS_ID_* macro values across source/header files.

Examples & Templates

• partition_overlay_template.overlay: Starter fixed-partitions overlay for app + storage.

Validation Checklist

• nvs_mount() succeeds on boot for the configured storage partition.
• Written values survive reset and read back with matching length and content.
• Partition layout in DTS matches runtime flash-map queries.
• Repeated write cycles do not produce mount/read corruption errors.

Resources

• References:
  • nvs_storage.md: Using NVS for data blobs and integers.
  • flash_management.md: Devicetree partitions and page information.
• Scripts:
  • nvs_id_lint.py: Duplicate ID detector for NVS namespaces.
• Assets:
  • partition_overlay_template.overlay: Flash partitioning template.