User AT Commands
AT+USERRAM: Operate user’s free RAM.
AT+USEROTA: Upgrade the firmware according to the specified URL.
AT+USERDOCS: Query the ESP-AT user guide for current firmware.
AT+USERRAM: Operate user’s free RAM
Query Command
Function:
Query the current available user’s RAM size.
Command:
AT+USERRAM?
Response:
+USERRAM:<size>
OK
Set Command
Function:
Operate user’s free RAM
Command:
AT+USERRAM=<operation>,<size>[,<offset>]
Response:
+USERRAM:<length>,<data> // esp-at returns this response only when the operator is ``read``
OK
Parameters
<operation>:
0: release user’s RAM
1: malloc user’s RAM
2: write user’s RAM
3: read user’s RAM
4: clear user’s RAM
<size>: the size to malloc/read/write
<offset>: the offset to read/write. Default: 0
Notes
Please malloc the RAM size before you perform any other operations.
If the operator is
write
, wrap return>
after the write command, then you can send the data that you want to write. The length should be parameter<length>
.If the operator is
read
and the length is bigger than 1024, ESP-AT will reply multiple times in the same format, each reply can carry up to 1024 bytes of data, and eventually end up with\r\nOK\r\n
.
Example
// malloc 1 KB user's RAM
AT+USERRAM=1,1024
// write 500 bytes to RAM (offset: 0)
AT+USERRAM=2,500
// read 64 bytes from RAM offset 100
AT+USERRAM=3,64,100
// free the user's RAM
AT+USERRAM=0
AT+USEROTA: Upgrade the Firmware According to the Specified URL
ESP-AT upgrades firmware at runtime by downloading the new firmware from a specific URL.
Set Command
Function:
Upgrade to the firmware version specified by the URL.
Command:
AT+USEROTA=<url len>
Response:
OK
>
This response indicates that AT is ready for receiving URL. You should enter the URL, and when the URL length reaches the <url len>
value, the system returns:
Recv <url len> bytes
After AT outputs the above information, the upgrade process starts. If the upgrade process is complete, the system return:
OK
If the parameter is wrong or firmware upgrades fails, the system returns:
ERROR
Parameters
<url len>: URL length. Maximum: 8192 bytes.
Note
The speed of the upgrade depends on the network status.
If the upgrade fails due to unfavorable network conditions, AT will return
ERROR
. Please wait for some time before retrying.After you upgrade the AT firmware, you are suggested to call the command AT+RESTORE to restore the factory default settings.
AT+USEROTA
supportsHTTP
andHTTPS
.After AT outputs the
>
character, the special characters in the URL does not need to be escaped through the escape character, and it does not need to end with a new line(CR-LF).When the URL is
HTTPS
, SSL verification is not recommended. If SSL verification is required, you need to generate your own PKI files and download them into the corresponding partition, and then load the certificates in the code implemented by theAT+USEROTA
command. Please refer to How to Generate PKI Files for PKI files. ForAT+USEROTA
command, ESP-AT project provides an example of USEROTA.Please refer to How to Implement OTA Upgrade for more OTA commands.
Example
AT+USEROTA=36
OK
>
Recv 36 bytes
OK
AT+USERDOCS: Query the ESP-AT User Guide for Current Firmware
Query Command
Function:
Query the ESP-AT English and Chinese user guide for current running firmware.
Command:
AT+USERDOCS?
Response:
+USERDOCS:<"en url">
+USERDOCS:<"cn url">
OK
Parameters
<”en url”>: the URL for English document
<”cn url”>: the URL for Chinese document
Example
AT+USERDOCS?
+USERDOCS:"https://docs.espressif.com/projects/esp-at/en/latest/esp32/index.html"
+USERDOCS:"https://docs.espressif.com/projects/esp-at/zh_CN/latest/esp32/index.html"
OK