What does -1 return code from AT command mean?

I recently bought two “WiFi Serial Tranceiver Moudules” model 68Y0156. I have been trying to get one to work with a simple Arduino program that does nothing but send the module an AT command to it, and read the message returned from the module. According to the manual, if I send “AT” I should receive “OK” in return. But I actually get -1.

I used the diagram from here https://wiki.seeedstudio.com/WiFi_Serial_Transceiver_Module/ which shows how to connect the module to an Arduino. I’ve checked my wiring a dozen times, so I’m pretty sure it’s right. I’m using a Mega2560, and have connected the module to tx1/rx1 of the Mega so I am using hardware serial rather than the software serial option shown in the example on that page, but I think that should make no difference. Just in case it does I tried softserial as well, but got the same result.

I found another post that recommended using Serial.write (rather than Serial.println) but I couldn’t get it to work with a variable name, i.e. Serial.write(mystring); failed to compile, but Serial.write("AT+RST"); compiled okay, but still gave me the -1 return code.

What does return code -1 mean? What do I need to do to get this module to work?

All advice gratefully received.

ESP8266 needs to burn AT firmware to have AT serial port function. I found the ESP8266 AT firmware and documentation for you.
https://www.espressif.com/en/support/download/at

Hi @Baozhu and thank you for you response.

I am just an amateur hobbyist, so I am unsure which firmware I should be downloading. I haven’t used ESP8266 before (or WiFi). There are several different versions so I downloaded the latest one, called ESP8266 NonOS AT Bin V1.7.3. Is this the correct version? I’m just interested in using WiFi to communicate to other devices, not connecting to the net or the cloud or anything.

I also don’t know how to burn the software to the device. I explored your site but I have to confess I ended up more confused than ever! Can you please point me to the documentation or instructions on how to do it? I am using the Arduino IDE so far, with the device connected to an Arduino Mega2560. Can I use the same setup to burn the firmware to the device?

Thanks for you help.

Sorry, this is not a Seeed product. I can only search for your information on Google for you.

Isn’t it this one?

This is Seeed’s e-commerce site. We help our partners who don’t have e-commerce sites to sell their products. The maintenance and management of the product is actually the responsibility of the partner.

Hi @Baozhu, thanks for the explanation. I hope you understand my assumption that you would support the product as it is advertised on your site and you also have a tutorial about how to use it on your site too.

Could you please advise who the partner is so I can find the forum for their products and perhaps get help there?

Thanks, and I appreciate your help.

http://wiki.ai-thinker.com/_media/esp8266/esp8266_series_modules_user_manual_v1.1.pdf
https://docs.ai-thinker.com/esp8266