By peetscholsem

I have a problem with a wifi shield v3.0.
The arduino romeo v2.2 send a command AT with serial1.println but the wifi not respond.
I place the oscilloscope on RX and i have not of respond.
Furthermore, i measure a voltage of 3.5V...? (not 5V?).
Do i put a resistor of pull-up?

Thank in advance,

Best regards
By peetscholsem
I connect the shield with USB on the PC and i receive nothing ! (I send "AT\r\n" or "AT\r" but not of reception)
The connections RX and TX is weld correctly. (check with multimeter)
By Leff
Hi peetscholsem,

Just pass-by and saw your post... you may check:

  1. can it be used on Uno, instead of Leonardo?
  2. <CR+LF>, i.e. \r\n, means Carriage-Return and Line-Feed, which is the same meaning with "Both NL & CR" in Arduino Serial monitor, do not include the string "<CR+LF>" itself.

could you post some pictures?

Maybe tomorrow I can test this module with Leonardo.
By peetscholsem
Hi Leff

A : I have not an uno but i have an arduino mini.
B : I have not to try with LF then CR. I can to try with "Serial.print("AT\n\r");" or "Serial.write("("AT\n\r");".

I have also to connect the wifi shield on the PC with a USB key and the UART connector. I can send any commands with "docklight".

Little precision, the Leds Power and Ready are lit.

What do you want as picture ?
By peetscholsem
There is news.
The connection with USB key receive the datas if i configure the wifi shield with the web page ( I connect me with my smartphone on the server of wifi shield. And i receive the datas in "Docklight". On the other side, the command AT always don't work ?!
By Leff

I found nothing talking about how to use AT command in the wiki. However, I found some notes in its user manual, here is the manual download link ... 20V2.4.pdf

And at page 53 and 54, it reads this:

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So I tried on UNO through Serial monitor, no problem as you could see:

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Also I wrote a simple code for Leonardo, after uploading, OPEN the Serial monitor, I could see I successfully entered AT mode and received responce.

the code:

Code: Select all
void setup() {
  while (!Serial) {
  Serial.println("Prepare to enter AT mode.");
  while (Serial1.available()) {
    char inData =;
    if ( inData == 'k') {
      Serial.println("Entered AT mode.");

void loop() {
  while (Serial1.available()) {

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By peetscholsem
Thank you very much.
I try this evening.
I don't watch correctly.
I have used an esp8266 and i had to send the commands AT...
It's strange to send "+++" but it's write in the datasheet !
By peetscholsem
Yes, of course !
I sent the commands of ESP and not of wifi shield...

I come to test your commands of wifi shield and it work !

Again thank. :D
By Leff
Aho, got it, so you sent the AT commands originally for ESP to this wifi shield...seems you are browsing many wifi modules.

Just a interesting question Id like to know, which module do you love the most? ;)