ESP-01 connection with Arduino UNO
I have just been working on a project involving Arduino (Nano) and an ESP.
A few notes from my experience:
* The ESP-01 has a bit delicate pinouts. I had multiple times when I had thought there is something wrong with the module and it was all OK after I pressed the pinouts with my fingers (on the soldered side).
* I highly recommend to reset the module with the reset pin (connect it to one of the Arduino's pins, set the pin to LOW and then HIGH again).
* You can definitely use UNO with it with the following adaptations:
A - Connect ESP TX pin to UNO directly
B - Connect ESP RX pin to UNO with a voltage splitter (using 3 identical resistors)
C - Use SoftwareSerial and define the appropriate pins as RX/TX. Do note that using SoftwareSerial limits the bit rate one can use. I recommend using 9600bps.
D - Don't forget to define the module's working bitrate to 9600bps too. The right AT command changes from FW to FW, try using AT+BAUD or AT+CIOBAUD
E - Connect the Vcc pin to the UNO's 3v3 pin. You can connect it to an external power supply, just make sure the ground is shared between the module, UNO and power supply.
* In order for you to be able to debug this properly I would suggest the following setups:
A - Communicating with the module via FTDI to usb converter
B - Communicating with the module via Arduino with a simple sketch that only transfer the commands from UNO's serial to the ESP software serial (and back)
C - Using your own sketch
This way, whenever there is a problem you can easily figure out whether it's a hardware or software problem.
For any additional help feel free to send me a message.
http://nicuflorica.blogspot.ro/2015/03/modulul-de-retea-uairles-esp8266-05-si.html