I have a hc-05 module. A module tinysine without button and the same one has pin NC already saw different tutorials and counties of how to enter in AT mode and I can not do it. Many tutorials demonstrate enable or key pin but this module only has the NC pin which I do not know what it does because in the datasheet it does not say what it is for anyway the module comes with an EN pin.
NC usually mean No Connection
If you need more information post links to the datasheet(s) for your module(s).
His other post about the same topic http://forum.arduino.cc/index.php?topic=535965.0 just 16 minutes before this one !
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You need to be more forthcoming about what you have. I'm not aware of a Tinysine HC-05, and I think it is an HM-10. This would explain the absence of the button as the HM-10 does not use one. It is in AT mode by defauilt and stays that way until you make a bluetooth connection. Some HM-10s come on a ZS-040 board with six pins of which EN is just decoration, and possibly the STATE pin as well.
Yep, not an HC-05, hence no button.