I'm trying to connect my Arduino Uno to an ESP-01 module, but I can't get it to start correctly. All I can get out from the ESP-01 is an "invalid" message when it is enabled. Can anyone please help? Additional information can be found below.
Here's my configuration:
- Arduino connected to a computer via USB cable (serial connection working)
- ESP-01 connected to the same UART connection, TX from Arduino is lowered to 3,3V with resistors
- ESP-01 powered with external battery + capacitor to ensure sufficient current
- I've tried all different configurations with GPIO0 and GPIO2 connecting them to ground and 3,3V, with and without resistors.
- I've tried 3 different ESP modules
Here's how things work:
- Arduino sends back every received UART transmission so that I can monitor the whole thing.
- I can send messages to Arduino from a terminal on the PC and Arduino responds.
- I can send messages from Arduino by pressing a button and the messages can be seen on the terminal.
- When I send AT\r\n from Arduino I can read it on the terminal but nothing happens on the ESP-01.
- When I send exactly the same message from the terminal, the blue light on ESP flashes but there is no response from the ESP. Arduino sends that message back to terminal of course.
- When I connect CH_PD to 3,3V the ESP gives a message: Ai-Thinker Technology Co. Ltd. invalid
- The baud rate is correct (115200) since I can only read that invalid message on this rate
