Partitions

FireFly Controller uses a custom board, typically using the ESP32 WROVER-E Module featuring 16MB flash storage (ESP32-WROVER-E-N16R8).

The partition table is defined per hardware model in devices.yaml and generated automatically at build time — there is no static partitions.csv committed to the repository. Partition sizes can differ between hardware models; the table below reflects the layout used by all current active hardware variants.

Name	Type	SubType	Offset	Size (Hex)	Size (Human)	Flags
nvs	data	nvs	0x9000	0x5000	20KB
otadata	data	ota	0xe000	0x2000	8KB
app0	app	ota_0	0x10000	0x640000	6.25MB
app1	app	ota_1	0x650000	0x640000	6.25MB
config	data	spiffs	0xC90000	0x80000	512KB
ui	data	spiffs	0xD10000	0x2E0000	2.875MB
coredump	data	coredump	0xFF0000	0x10000	64KB

Note: The spiffs SubType label is an ESP32 toolchain partition type identifier. The config and ui partitions both use the LittleFS filesystem, not SPIFFS.

How the partition table is created and updated

The partition layout for each hardware model lives in devices.yaml under each device's partition_scheme list. Each entry specifies the partition label, type, subtype, offset, and size.

At build time, the CI workflow generates a partitions.csv for the specific device being compiled by querying devices.yaml using yq and jq. The generated file is written into the application directory before Arduino CLI compiles the firmware, so each hardware variant receives its own correctly-sized partition table binary.

devices.yaml also contains a per-device bootloader_addr field that specifies the flash address of the bootloader (e.g. 0x1000 for Xtensa LX6-based ESP32 variants). This value is written into the build manifest and propagated to the FireFly Cloud flash UI, so a new chip family can be supported by updating only devices.yaml.

To update or add a partition for a hardware model, edit the partition_scheme for that device in devices.yaml. The next build will automatically produce the correct partitions.csv — no other files need to be changed.

config partition

Data stored within this partition contains configuration data for the controller itself, such as:

• OTA Update Service configuration
• Certificates
• I/O and action configuration

It should only be formatted and flashed by the Hardware Registration and Configuration application.

🚫 It is ineligible to receive OTA updates via the OTA Update Service, nor via a forced OTA update.

This protection is enforced at two levels:

• Library level — the OTA library only permits writes to data filesystem partition types (LittleFS/SPIFFS or FAT). App, NVS, coredump, and other partition types are unreachable regardless of what the update server requests.
• Firmware level — the config partition is explicitly blocked by name in the application firmware. Removing it from the block list requires shipping a firmware update first, making accidental overwrites a deliberate two-step process.

The partition size is 512KB.

ui partition

Files stored on this partition are used for web user interface or other blobs of data.

✅ It is eligible for OTA updates, and therefore data stored on this partition will be lost during an OTA update of the partition.

The partition size is 2.875MB.