SIMPLE_FS

Simple file system for application of sensoric data. Support fast append to file operation. More...

Collaboration diagram for SIMPLE_FS:

Modules
	Format_specification
	Definition of internal structures with format definitions.
	SFS_API
	API function of simpleFileSystem The API functions are divided in:
	Memory_interface
	low level interface to specific types of used memories
	Sensor_specification
	Definition of sensoric/data modules in simple FS.

Detailed Description

Simple file system for application of sensoric data. Support fast append to file operation.

Type of FS: RA (Read-Append). Optimized for FLASH-like types of memories, where write/erase operation is much time consuming that reading.

Parts in simple FS:

• PREAMBLE: first 32 bytes, system information start at address 0, size: 32B
• HEADER: contains list of files, each record is 32B long Size of HEAD area: 1024B, support up to 31 files start at address 32, the begining of file table Start address: 0
• META: contains list of sensors for one file. Each record is 512B long each sensor contains of 11B: 8B for ID and 3B for meta information one meta record (one file) can contain 46 sensors (46*11B = 506B). Start address: 1024 Size of META area: 11264 B (12Kb - 1 kb header)
• DATA: Start address: 12288

Memory map

Area	Start address	Size
PREAMBLE	0x0	32B (0x20B)
HEADER	FILE_HEADER_ADDRESS - 32 (0x20)	32B - 704 B
META	FILE_META_ADDRESS	48 - 11088 B
DATA	FILE_DATA_ADDRESS	up to memory capacity

Used data structures

PREAMBLE

Structure: FS_Header_t

typedef struct {
   uint8_t version;
   uint8_t manufacturer;
   uint8_t memory_type;
   uint8_t memory_capacity;
   uint8_t memory_id[8];
} FS_Header_t;

Mapping

0	1	2	3	4	5	6	7	8 - 15	16	17	18	19 - 32
's'	'F'	'S'	'1'	M	T	C	0	sFS_ID	CC	MF	MS	NOT_USED

• bits 0..4: "sFS1"
• bit 3: version of sFS
• M - manufacturer code
• T - Memory type code
• C - Capacity code
• sFS_ID - 8B hardware ID
• CC - Size variant
• MF - Max files in sFS
• MS - max sensors/columns in one file.

HEADER

• start address 32
• contains records of length FILE_DESCRIPTOR_SIZE (32B). (FileDescriptor_t) Each record contains of:
  • FILE_ID 1B - ID of file
  • META_ADDRESS 4B - address of meta file description (list of sensors)
  • DATA_ADDRESS 4B - address of file beginning
  • FILE_NAME 16B - filename (ASCII)
  • NUM_PARTS 1B - number parts in one record (one measure form all sensors)
  • RECORD_LENGTH 2B - Length of one record in file in bytes.
• FILE_FORMAT 3B for each sensor in file. Number of these parts is NUM_PARTS. (RecordDescriptor_t) It contains of:
  • SENSOR_TYPE 1B - enumerate sensor type (SensorType_t)
  • VALUE_TYPE 2B - contains format for stored value (RecordTypeValue_t)

Mapping (FileDescriptor_t)

FILE_ID	META_ADDRESS	DATA_ADDRESS	FILE_NAME	NUM_PARTS	RECORD_LENGTH	not used
1B	4B	4B	16B	1B	2B	4B

Capacity of HEADER area:

• Single file occupied 32B in HEADER area.

Used data structure combine HEADER data and META data of file:

 typedef struct {
    uint8_t ID;
    uint32_t meta_address;
    uint32_t data_address;
    uint8_t name[FILENAME_LENGTH];
    uint8_t num_parts;
    RecordDescriptor_t format[MAXIMUM_FS_SENSORS_PER_FILE];
    uint16_t record_length;
    uint16_t recordAddressMap[MAXIMUM_FS_SENSORS_PER_FILE];
} FileDescriptor_t;

META

• start address: FILE_META_ADDRESS
• length: 48B - 11088B (depending on selected variant)
• Size of 1 meta block is: META_RECORD_LENGTH (48-504B)
  • this block contains fixed sized block of size 12B
    • SENSOR_ID maximum 8B
    • SENSOR_TYPE 1B enumerate type of sensor
    • SENSOR_VALUE_FORMAT 3B enumerate value format of sensor value
• Number of columns/sensors in file: META_RECORD_LENGTH/12

Mapping (RecordDescriptor_t)

SENSOR_ID	SENSOR_TYPE	VALUE_FORMAT
8B	1B	3B

Used data structure combine HEADER data and META data of file:

 typedef struct {
    uint8_t sensor_id[8];
    SensorType_t sensor_type;
    RecordTypeValue_t value_format;
} RecordDescriptor_t;

VALUE_FORMAT is data structure with definition:

typedef struct {
      ValueFormatMetaFmt_t meta_format;
      ValueFormatMetaLength_t meta_length;
      RecordTypeQ_t Q;
} RecordTypeValue_t;

Mapping (RecordDescriptor_t)

META_FORMAT | META_LENGTH	Q
1B, details in: RecordTypeValue_t	2B (RecordTypeQ_t)

DATA

• contains file content
• starting address: FILE_DATA_ADDRESS
• file contains of fixed size records (or rows). The size of single row is defined by RECORD_LENGTH

Datastructure:

typedef struct {
    uint8_t *value;
    SensorType_t type;
    uint8_t data_length;
}SensorValue_t;