ESP8266 returns whatever is sent through Arduino serial

Question

I am a newbie and working on a kind of WiFi-controlled vehicle (car or maybe hovercraft later). My ESP8266 repeats the commands I send. For example, AT gives AT, AT+GWR gives AT+GWR, dabdabik gives dabdabik, etc.

I am using an Arduino Uno to send commands, as I don't have FTDI related stuff (USB to Serial Converter). I use AA cells for power supply (1.5v*2=3v). I don't even have 3.3 volt direct supply. I am using the Arduino IDE Serial Monitor. I connected the Arduino's TX to the ESP8266's RX via a voltage divider (1.66K Ohm(TX) and 1.66K Ohm (GND)->3.29 Ohm(RX)).

My connections are:

ESP8266----------------Arduino Uno
TX---Voltage divider---RX(d0)
RX---------------------TX(d1)
GND--------------------GND
VCC-------**3V**
CH_PD-----**3V**

Sometimes it gives garbage otherwise it just repeats (weird). Garbage ONLY changes if baud rate is changed.

I flashed it (it seems) with the AT 9.5.2 firmware. Flashing works rarely ONLY with TX to TX connected directly without a voltage divider.

I tried as much as I could after searching the web and ESP8266 forum but still couldn't solve problem.

Please help. I am a student in a small town (Manipal) in Southern India so no good stores nearby and I don't want to buy FTDI or anything online. I am a bit new to electronics, but I am a C++ programmer and student.

UPDATE: I noticed after some resets that it gives full garbage to longer commands most of the time, whereas two-letter commands give partial garbage. For example AT gives IT,TT,OT,etc.

There is no coding. I am sending the commands directly via Arduino hardware serial pins (rx,tx) and a bare minimum program.

Answer 1

I noticed when testing my ESP8266 using the Arduino IDE serial console that ending with a CR repeated what was sent, a NL executed the command and combination of the two yielded a combination of the two behaviours. This could have just been the firmware on mine (it seemed to be non-standard), but it is possible that the behaviour is similar on yours. If you are using CR & NL, it would explain repetition. However, I can't explain commands not executing, or executing abnormally.

Answer 2

When I recieved my first ESP I struggled for weeks trying to get it working. First, the voltage divider is a good thing for its longevity but I got it working without it.

Next about baudrate, mine sent some data at startup on 76800 baud then would work on 9600 baud. You might want to check that out for the garbage you're seeing.

Finally, it might be related to a power draw problem. The ESP has 400mA peaks, this is high for an Arduino and even for a 3.3v USB serial programmer. I had to use a 1A breadboard power supply to actually get it to work. Before buying anything you should try putting a big (220µF or more) capacitor in parallel on the 3.3V power.

Answer 3

1. AT commands must end with '\r\n'.
2. 'ATE'commands can enable/disable echo. (ATE0: disable, ATE1: enable)
3. AT commands documentation: http://espressif.com/sites/default/files/documentation/4a-esp8266_at_instruction_set_en.pdf