File System AT Commands

Note

The File System AT commands are enable by default and cannot be disabled.
AT+FS command performs corresponding operations in the AT directory of the file system.
AT+CERT and AT+CERTSET commands perform corresponding operations in the CERT directory of the file system.
AT+FSRGN command configures the file system region for the above command operations.
If you want to preload files, refer to Preload Example.
Prior to performing file write operations, validate both file system available capacity and dynamic memory free space to ensure sufficient resource allocation.

AT+FS

Function Description

Perform file system operations, including deleting files, reading files, writing files, getting file sizes, and listing files.

Command Format

AT+FS=<operation>[,<filename>,<offset>,<length>]

Response Format

Successful Response:

OK

Error Response:

ERROR: <error_no>

Parameters

<operation>:

File operation type

0: List files in directory
1: Delete file
2: Get file size
3: Read file
4: Write file

<filename>:

File name string

Length not exceeding 253 bytes

<offset>:

Starting position for reading or writing

<length>:

Length to read or write

Error Codes

1: Format error
2: Operation failed

Note

When <operation> is set to write, the system will enter Transparent Transmission (TT) Mode mode.

Examples

List files in the directory:
```
AT+FS=0

OK
```
Delete the file test.txt:
```
AT+FS=1,"test.txt"

OK
```
Get size of file data.bin:
```
AT+FS=2,"data.bin"
+FS: 1024

OK
```
Read 50 bytes from the file log.txt starting at offset 100:
```
AT+FS=3,"log.txt",100,50
+FS: <read data>

OK
```

Write 100 bytes of data to the file new.dat:

AT+FS=4,"new.dat",0,100
>>>
<send 100 bytes of data>

OK

AT+CERT

Function Description

Query the certificate components of the server or client

Command Format

AT+CERT=<role>,<index>

Response Format

Successful Response:

<Certificate name 1>
<Certificate content 1>

<Certificate name 2>
<Certificate content 2>

<Certificate name 3>
<Certificate content 3>

OK

Error Response:

ERROR: <error_no>

Parameters

<role>:

Certificate component type

0: Client
1: Server

<index>:

Certificate component index

Range: 1~10

Error Codes

1: Parameter error

AT+CERTSET

Function Description

Write the certificate components of the server or client

Command Format

AT+CERTSET=<role>,<type>,<index>,<length>

Response Format

Successful Response:

OK

Error Response:

ERROR: <error_no>

Parameters

<role>:

Certificate component type

0: Client
1: Server

<type>:

Certificate file type

0: CA certificate, saved as <role>_ca_<index>.crt
1: Certificate, saved as <role>_cert_<index>.crt
2: Private key, saved as <role>_key_<index>.key

Where <role> is client or server.

<index>:

Certificate component index

Range: 1~10

<length>:

Number of bytes to write

Range: 1~4096

Error Codes

1: Parameter error
2: Operation failed, for example, the file system region does not exist, memory is insufficient, or the transparent transmission is interrupted
3: Failed to open or write the file

Note

After executing this command, the system will enter Transparent Transmission (TT) Mode mode, and <length> bytes of certificate data need to be sent.
If the CERT directory does not exist, it will be created automatically. If the target file already exists, it will be overwritten.
After writing, use AT+CERT to query the certificate components.

Examples

Write a 1200-byte client CA certificate with index 1, saved as CERT/client_ca_1.crt:

AT+CERTSET=0,0,1,1200
>>>
<send 1200 bytes of certificate data>

OK

AT+FSRGN

Function Description

Configure the file system command operation region.

Command Format

AT+FSRGN=<vfs region>

Response Format

Successful Response:

OK

Error Response:

ERROR: <error_no>

Parameters

<vfs region>:

File system region

1: region 1
2: region 2
3: region 3
4: region 4

Error Codes

1: Parameter error