Arduino ESP8266 AP join error troubleshoot for Cactus Micro

This article related to Cactus Micro's Arduino Mini + ESP8266 combined module.

http://wiki.aprbrother.com/wiki/Cactus_Micro

Open Arduino IDE and choose board "LilyPad USB" to start

arduino base board and ESP8266 was connected via SoftwareSerial.

Arduino	ESP8266
11 (rx)	tx
12 (tx)	rx
13 (Digtal Out)	CH_PD

to make ESP8266 activate, CH_PD should be HIGH (LOW is Firmware Upgrade mode)

Using Hardware Serial to Software Serial bypass code, PC serial monitor program access the ESP8266 directly.

<SerialBypss.ino file attached here>

SerialBypass.ino

Don't missed make Pin #13 to be HIGH to make ESP8266 working normal mode.

recommend "CoolTerm" program (most robust program ever I used)

Don't missed add "CR"+"LF" at the end of each command.

ESP8266 can understand (parsing) command when received "CR","LF" byte.

[if check this option, whenever you key-in "enter"key, it automatically trasmit "CR,"LF"]

my ESP8266 factory setting as 9600baud speed. firmware version 0.21.0.0

ESP8266 AT COMMAND guide

Reset	AT+RST
version check	AT+GMR
operation mode	AT+CWMODE=1	1:station(client) 2:AP(server) 3:Both
AP(Access Point) Search	AT+CWLAP
Connect(Join) to AP	AT+CWJAP="SSID_NAME","PASSWORD"

There is a problem occured!!

when I try to connect AP, there is response like below

+resp:4

FAIL

There is no error message explain manual!!

I found +resp:2 means "wrong password"

SOLUTION for "+resp:4"

change your AP's access mode to "WPA-PSK" "AES" then it works!!

not working for : "WPA2-PSK"+"AES" or "WPA2-PSK"+"TKIP" or "WPA-PSK"+"TKIP"

If I upgrad my ESP8266 modle, then may it can be fixed. BUT to upgrad module, hardware rework needed!

How to change the serial port for Cactus Micro

[above link is manual : its software serial port (arduino 11,12) to Hardware Serial (arduino 0,1)]