Category Archives: microcontrollers

microcontrollers, programming

How To Directly Program An Inexpensive ESP8266 WiFi Module

The ESP8266 is the answer to “I want something with Wifi.” Surprisingly, there are a number of engineers and hobbyists who have not heard of this chip or have heard of it but don’t really understand what it is. It’s basically the answer to everything IoT to so many engineering problems that have plagued the hobbyist and commercial world alike.

The chip is a processor with integrated RAM, some ROM, and a WiFi radio, and the only external components you will need are 4 capacitors, a crystal and an external flash! It’s CHEAP, like $4/ea cheap! Or $5 if you want it on a nice, convenient carrier board that includes all these components. The power consumption is reasonable (~200mA)1, the range is insane ~300m2 without directional equipment, and a PCB trace antenna and ~4km if you want to be ridiculous.

The processor by default runs at 80 MHz but can go up to 160 MHz, it has ~80kB DRAM (Data RAM), and ~35kB of high speed IRAM (Instruction RAM).4 Yes, that means it uses a Harvard architecture. The IRAM is loaded at boot with whatever the user wants to keep on-processor, though the processor can run code directly off of the external flash at a lower speed.

Source: How To Directly Program An Inexpensive ESP8266 WiFi Module | Hackaday

arduino, ESP32, microcontrollers

ESP8266 – AT Command Reference · room-15

ESP8266 – AT Command Reference

ESP8266, in it’s default configuration, boots up into the serial modem mode. In this mode you can communicate with it using a set of AT commands.  AT commands that ESP8266 supports, explain what they do and how to use them.

Historically AT commands are based on the Hayes Command Set and these are no different.

AT Commands

Index of all known AT commands

Basic WiFI layer TCPIP Layer
AT AT+CWMODE AT+CIPSTATUS
AT+RST AT+CWJAP AT+CIPSTART
AT+GMR AT+CWLAP AT+CIPSEND
AT+GSLP AT+CWQAP AT+CIPCLOSE
ATE AT+CWSAP AT+CIFSR
AT+CWLIF AT+CIPMUX
AT+CWDHCP AT+CIPSERVER
AT+CIPSTAMAC AT+CIPMODE
AT+CIPAPMAC AT+CIPSTO
AT+CIPSTA AT+CIUPDATE
AT+CIPAP +IPD

Line termination

ESP8266 expects <CR><LF> or CarriageReturn and LineFeed at the end of each command, but just<CR> seems to work too.

Command variants

Each command can have up to 4 variants changing the function of it. You can chose between them by appending one of four possible values to the end of the root command itself. These four appendices can have the following values "",=<parameter|[parameters]>,"?",=?

Type Example Description
Test AT+CIPSTART=? Query the range of values (So far only AT+CWMODE=? uses it)
Query AT+CMD? Returns the current value of the parameter.
Set AT+CMD=Parameter Set the value of user-defined parameters in commands and run.
Execute AT+CMD Runs commands with no user-defined parameters.
Note:
  • Not all AT commands support all 4 variants.
  • [] = default value, not required or may not appear.
  • String values require double quotation marks, for example: AT+CWSAP="ESP756190","21030826",1,4.
  • Baud rate = 115200
  • AT instruction ends with “\r\n”

Commands

AT – Test AT startup

Variant Command Response Function
Execute AT OK Test if AT system works correctly

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AT+RST – Restart module

Variant Command Response Function
Execute AT+RST OK Reset the module

ESP-01 Output after reset:

 ets Jan  8 2013,rst cause:4, boot mode:(3,7)

wdt reset
load 0x40100000, len 24444, room 16
tail 12
chksum 0xe0
ho 0 tail 12 room 4
load 0x3ffe8000, len 3168, room 12
tail 4
chksum 0x93
load 0x3ffe8c60, len 4956, room 4
tail 8
chksum 0xbd
csum 0xbd

ready

ESP-12 Output after reset:

\0x04B1\0x85 \0xff\0x13:'\0xe0;\0xcc;!G\0xfa\0x11\0xa9R\0xc6\0x83\0x01\0xd9\0x81
[Vendor:www.ai-thinker.com Version:0.9.2.4]

ready

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AT+GMR – View version info

Variant Command Response Function
Execute AT+GMR version, OK Print firmware version
Parameters:
  • version: firmware version number
ESP-01 output:
00160901
ESP-12 output:
0018000902-AI03

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AT+GSLP – Enter deep-sleep mode

Variant Command Response Function
set AT+GSLP=time time OK Enter deep sleep mode for time milliseconds
parameters:
  • time: Time to sleep in milliseconds
Example：

AT+GSLP=1500

Note:

Hardware has to support deep-sleep wake up (Reset pin has to be High).

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ATE – Enable / Disable echo

Variant Command Response Function
Execute ATE0 OK Disable echo (Doesn’t send back received command)
Execute ATE1 OK Enable echo (Sends back received command before response)
Note:

I haven’t had any luck with this command yet. Both ATE0 and ATE1 return no this fun.
ATE returns OK
This changed with ESP-12 where the command functions exactly as expected!

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AT+CWMODE – WIFI mode（station, AP, station + AP）

Variant Command Response Function
Test AT+CWMODE=? +CWMODE:(1-3) OK List valid modes
Query AT+CWMODE? +CWMODE:mode OK Query AP’s info which is connect by ESP8266.
Execute AT+CWMODE=mode OK Set AP’s info which will be connect by ESP8266.
Parameters:
  • mode： An integer designating the mode of operation either 1, 2, or 3.
    1 = Station mode (client)
    2 = AP mode (host)
    3 = AP + Station mode (Yes, ESP8266 has a dual mode!)
Notes:

ESP-12 came configured as host with ssid set to ESP_A0A3F2, no password, channel 1 You can use AT+CWSAP? to find the current settings.

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AT+CWJAP – Connect to AP

Variant Command Response Function
Query AT+CWJAP? + CWJAP:ssid OK Prints the SSID of Access Point ESP8266 is connected to.
Execute AT+CWJAP=ssid,pwd OK Commands ESP8266 to connect a SSID with supplied password.
Parameters:
  • ssid：String, AP’s SSID
  • pwd：String, not longer than 64 characters
Example：
AT+CWJAP="my-test-wifi","1234test"
Example AT+CWJAP?：
+CWJAP:"my-test-wifi"

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AT+CWLAP – Lists available APs

Variant Command Response Function
Set AT+CWLAP=ssid,mac,ch +CWLAP:ecn,ssid,rssi,mac OK Search available APs with specific conditions.
Execute AT+CWLAP AT+CWLAP:ecn,ssid,rssi,mac OK Lists available Access Points.
Parameters:
  • ecn:
    • 0 = OPEN
    • 1 = WEP
    • 2 = WPA_PSK
    • 3 = WPA2_PSK
    • 4 = WPA_WPA2_PSK
  • ssid: String, SSID of AP
  • rssi: signal strength
  • mac: String, MAC address
Note:

On ESP-01 I have had no luck with the set version of this command (AT+CWLAP=...). If you know what it does please let me know.
On ESP-12, the Set version of the command allows to see if a certain SSID, with certain MAC on certain channel exists. If it doesit is returned as one line of the Execute version of this command.

Example AT+CWLAP:
+CWLAP:(3,"CVBJB",-71,"f8:e4:fb:5b:a9:5a",1)
+CWLAP:(3,"HT_00d02d638ac3",-90,"04:f0:21:0f:1f:61",1)
+CWLAP:(3,"CLDRM",-69,"22:c9:d0:1a:f6:54",1)
+CWLAP:(2,"AllSaints",-88,"c4:01:7c:3b:08:48",1)
+CWLAP:(0,"AllSaints-Guest",-83,"c4:01:7c:7b:08:48",1)
+CWLAP:(0,"AllSaints-Guest",-83,"c4:01:7c:7b:05:08",6)
+CWLAP:(4,"C7FU24",-27,"e8:94:f6:90:f9:d7",6)
+CWLAP:(2,"AllSaints",-82,"c4:01:7c:3b:05:08",6)
+CWLAP:(3,"QGJTL",-87,"f8:e4:fb:b5:6b:b4",6)
+CWLAP:(4,"50EFA8",-78,"74:44:01:50:ef:a7",6)
+CWLAP:(0,"optimumwifi",-78,"76:44:01:50:ef:a8",6)
+CWLAP:(3,"BHQH4",-95,"18:1b:eb:1a:af:5b",6)
+CWLAP:(3,"NETGEAR49",-86,"84:1b:5e:e0:28:03",7)
+CWLAP:(3,"ngHub_319332NW00047",-56,"20:e5:2a:79:b1:2f",11)
+CWLAP:(3,"BFZR4",-73,"18:1b:eb:1d:c3:91",11)
+CWLAP:(1,"5FFVL",-82,"00:26:b8:b5:c0:f2",11)
+CWLAP:(3,"59G6D",-77,"00:7f:28:6d:91:7b",11)
+CWLAP:(3,"N16FU",-53,"20:cf:30:ce:60:fe",11)
+CWLAP:(3,"ITS",-82,"90:72:40:21:5f:76",11)
+CWLAP:(3,"ITS",-79,"24:a2:e1:f0:04:e4",11)
Example AT+CWLAP="N16FU","20:cf:30:ce:60:fe",11:
+CWLAP:(3,"N16FU",-53,"20:cf:30:ce:60:fe",11)

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AT+CWQAP – Disconnect from AP

Variant Command Response Function
Execute AT+CWQAP OK Disconnect ESP8266 from the AP is currently connected to.
Note:

After running this command, if you run AT+CWJAP? it still shows the AP you were connected to before. Back to Index

AT+CWSAP – Configuration of softAP mode

Variant Command Response Function
Query AT+CWSAP? +CWSAP:ssid,pwd,ch,ecn OK Query configuration of ESP8266 softAP mode.
Set AT+CWSAP=ssid,pwd,ch,ecn OK Set configuration of softAP mode.
Parameters:
  • ssid: String, ESP8266’s softAP SSID
  • pwd: String, Password, no longer than 64 characters
  • ch: channel id
  • ecn:
    • 0 = OPEN
    • 2 = WPA_PSK
    • 3 = WPA2_PSK
    • 4 = WPA_WPA2_PSK

Example
AT+CWSAP="esp_123","1234test",5,3
AT+CWSAP? => +CWSAP:"esp_123","1234test",5,3

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AT+CWLIF – List clients connected to ESP8266 softAP

Variant Command Response Function
Execute AT+CWLIF [ip,other] OK List information on of connected clients.
Parameters:

ip: IP address of a client connected to the ESP8266 softAP other: Other info, look at example. I don’t know what it means yet.

Example (ESP-01):
AT+CWLIF

192.168.4.100,3fff50b4:3fff50ba:3fff50c0:3fff50c6:3fff50cc:3fff50d2

OK
Example (ESP-12):
AT+CWLIF

192.168.4.100,c0:ee:fb:25:33:ec

OK

I ran the command after connecting to the ESP8266 with my cellphone.

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AT+CWDHCP – Enable/Disable DHCP

Variant Command Response Function
Set AT+CWDHCP=mode,en OK Enable or disable DHCP for selected mode
Parameters:
  • mode:
    • 0 : set ESP8266 as a softAP
    • 1 : set ESP8266 as a station
    • 2 : set both ESP8266 to both softAP and a station
  • en:
    • 0 : Enable DHCP
    • 1 : Disable DHCP
Note:

This command doesn’t seem to work on firmware 00160901 (ESP-01) nor 0018000902-AI03 (ESP-12).

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AT+CIPSTAMAC – Set MAC address of ESP8266 station

Variant Command Response Function
Query AT+CIPSTAMAC? +CIPSTAMAC:mac OK Print current MAC ESP8266’s address.
Execute AT+CIPSTAMAC=mac OK Set ESP8266’s MAC address.
Parameters:
  • mac： String, MAC address of the ESP8266 station.
Example:

AT+CIPSTAMAC="18:aa:35:97:d4:7b"

Note:

This command doesn’t seem to work on firmware 00160901

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AT+CIPAPMAC – Set MAC address of ESP8266 softAP

Variant Command Response Function
Query AT+CIPAPMAC? +CIPAPMAC:mac OK Get MAC address of ESP8266 softAP.
Execute AT+CIPAPMAC=mac OK Set mac of ESP8266 softAP.
Parameters:
  • mac： String, MAC address of the ESP8266 softAP.
Example:

AT+CIPAPMAC=”2c:aa:35:97:d4:7b”

Note:

This command doesn’t seem to work on firmware 00160901

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AT+CIPSTA – Set IP address of ESP8266 station

Variant Command Response Function
Query AT+CIPSTA? +CIPSTA:ip OK Get IP address of ESP8266 station.
Execute AT+CIPSTA=ip OK Set ip addr of ESP8266 station.
Parameters:
  • ip： String, ip address of the ESP8266 station.
Example:

AT+CIPSTA=”192.168.101.108”

Note:

This command doesn’t seem to work on firmware 00160901

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AT+CIPAP – Set ip address of ESP8266 softAP

Variant Command Response Function
Query AT+CIPAP? +CIPAP:ip OK Get ip address of ESP8266 softAP.
Execute AT+CIPAP=ip OK Set ip addr of ESP8266 softAP.
Parameters:
  • ip： String, ip address of ESP8266 softAP.
Example:
AT+CIPAP="192.168.5.1"
Note:

This command doesn’t seem to work on firmware 00160901

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AT+CIPSTATUS – Information about connection

Variant Command Response Function
Test AT+CIPSTATUS=? OK
Execute AT+CIPSTATUS STATUS:status +CIPSTATUS:id,type,addr,port,tetype OK Get information about connection.
Parameters:
  • status：
    • 2: Got IP
    • 3: Connected
    • 4: Disconnected
  • id： id of the connection (0~4), for multi-connect
  • type： String, “TCP” or “UDP”
  • addr： String, IP address.
  • port： port number
  • tetype：
    • 0 = ESP8266 runs as a client
    • 1 = ESP8266 runs as a server
Note:

On ESP-01 this command returns STATUS:1 instead (no extra info, but status changes) On 0018000902-AI03 this command returns STATUS:2 instead (no extra info, but status changes)

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AT+CIPSTART – Establish TCP connection or register UDP port and start a connection

Variant Command Response Function
Set AT+CIPSTART=type,addr,port OK Start a connection as client. (Single connection mode)
Set AT+CIPSTART=id,type,addr,port OK Start a connection as client. (Multiple connection mode)
Test AT+CIPSTART=? [+CIPSTART:(id)(“type”),(“ip address”),(port)] OK List possible command variations)
Parameters:
  • id: 0-4, id of connection
  • type: String, “TCP” or “UDP”
  • addr: String, remote IP
  • port: String, remote port

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AT+CIPSEND – Send data

Variant Command Response Function
Test AT+CIPSEND=? OK
Set AT+CIPSEND=length SEND OK Set length of the data that will be sent. For normal send (single connection).
Set AT+CIPSEND=id,length SEND OK Set length of the data that will be sent. For normal send (multiple connection).
Execute AT+CIPSEND Send data. For unvarnished transmission mode.

Normal Mode

Parameters:
  • id: ID no. of transmit connection
  • length: data length, MAX 2048 bytes

Unvarnished Transmission Mode

Wrap return “>” after execute command. Enters unvarnished transmission, 20ms interval between each packet, maximum 2048 bytes per packet. When single packet containing “+++” is received, it returns to command mode.

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AT+CIPCLOSE – Close TCP or UDP connection

Variant Command Response Function
Test AT+CIPCLOSE=? OK
Set AT+CIPCLOSE=id OK Close TCP or UDP connection.For multiply connection mode
Execute AT+CIPCLOSE OK Close TCP or UDP connection.For single connection mode
Parameters:
  • id： ID no. of connection to close, when id=5, all connections will be closed.
Note:

In server mode, id = 5 has no effect!

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AT+CIFSR – Get local IP address

Variant Command Response Function
Test AT+CIFSR=? OK
Execute AT+CIFSR +CIFSR:ip OK Get local IP address.
Parameters:
  • ip: IP address of the ESP8266 as an client.
Example AT+CIFSR:
10.101.10.134

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AT+CIPMUX – Enable multiple connections or not

Variant Command Response Function
Set AT+CIPMUX=mode OK Enable / disable multiplex mode (up to 4 conenctions)
Query AT+CIPMUX? +CIPMUX:mode OK Print current multiplex mode.
Parameters:
  • mode:
    • 0: Single connection
    • 1: Multiple connections (MAX 4)
NOTE:

This mode can only be changed after all connections are disconnected. If server is started, reboot is required.

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AT+CIPSERVER – Configure as server

Variant Command Response Function
Set AT+CIPSERVER=mode[,port] OK Configure ESP8266 as server
Parameters:
  • mode:
  • 0: Delete server (need to follow by restart)
  • 1: Create server
  • port: port number, default is 333
NOTE:
  1. Server can only be created when AT+CIPMUX=1
  2. Server monitor will automatically be created when Server is created.
  3. When a client is connected to the server, it will take up one connection，be gave an id.

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AT+CIPMODE – Set transfer mode

Variant Command Response Function
Query AT+CIPMODE? +CIPMODE:mode OK Set transfer mode,normal or transparent transmission.
Set AT+CIPMODE=mode OK Set transfer mode,normal or transparent transmission.
Parameters:
  • mode:
  • 0: normal mode
  • 1: unvarnished transmission mode

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AT+CIPSTO – Set server timeout

Variant Command Response Function
Query AT+CIPSTO? +CIPSTO:time Query server timeout.
Set AT+CIPSTO=time OK Set server timeout.
Parameters:
  • time: server timeout, range 0~7200 seconds

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AT+CIUPDATE – update through network

!!! Don’t run this unless you know what you’re doing !!!

!!! It will likely brick your device !!!

Attempts to self-update from the internet.

Variant Command Response Function
Execute AT+CIUPDATE +CIPUPDATE:n OK Start update through network
Parameters:

–n:

  • 1: found server
  • 2: connect server
  • 3: got edition
  • 4: start update
Example:
AT+CIUPDATE

+CIUPDATE: 1
+CIUPDATE: 2
+CIUPDATE: 3
+CIUPDATE: 4

\0x02\0x8cl\0x8el\0x8e\0x1cp\0x0c\0x8c\0xf2nn\0xee\0x00l\0x8c\0x8el`
\0x02\0x90\0x12\0x12nnl\0x8cl`\0x02\0x0e\0x02nr\0x8e\0x92\0x92n\0x0c\0x0c
\0x02\0x8c\0x92`\0x02`
\0xf2n\0x0c\0x0c\0x0c\0x9e\0xe0b\0x82nl\0x8c\0x0c\0x8c
\0xf2nn\0xee\0x00\0x0c\0x8e\0x0elp\0xf2n\0xe0\0x10\0x02\0x0c
\0x0cr\0x8c\0x9c\0x9c\0xe2\0xe0\0x0c\0x0c\0x0c
\0x0cb\0x0cn\0xe2|\0x02\0xec\0xecl\0x8c\0x0cb\0x8c\0xf2nn
...forever

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+IPD – Receive network data

Variant Command Response Function
Execute +IPD,len:data Receive network data from single connection.
Execute +IPD,id,len:data Receive network data from multiple connection.
Parameters:
  • id: id no. of connection
  • len: data length
  • data: data received
Note:

I have had no luck with this command so far.

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Sources

esp8266 GitHub Wiki

Source: ESP8266 – AT Command Reference · room-15