https://devzone.nordicsemi.com/f/nordic-q-a/34245/sending-commands-to-peripheral-in-nrf-toolbox-appHi all, I&#39;m currently learning on how to build bluetooth connections with a device from an app. For that I downloaded the iOS version of the nerf Toolbox app, as my chip is also from nRF. There I want to send some String to the peripheral with the lineen-USTelligent Community 13Mon, 14 May 2018 08:17:11 GMThttps://devzone.nordicsemi.com/thread/131806?ContentTypeID=1Mon, 14 May 2018 08:17:11 GMT137ad170-7792-4731-bb38-c0d22fbe4515:5879e518-0df1-47cc-bc1a-917611e10edcMostafa Berg<p>It&#39;s quite tricky to find out what went wrong here as we don&#39;t know how your peripheral works exactly, but the easiest way is to compile nRF Toolbox on your computer, and have a breakpoint at the point where we send the data to the characteristic, and compare&nbsp;the value of the `NSData` object being sent to the value your app is sending, this will show us at least if you&#39;re sending the correct data or not.<br /><br />Another thing to look out for is that you&#39;ve enabled notification on the characteristic too so you&#39;ll be able to receive data. maybe you&#39;ve forgotten that ?</p><div style="clear:both;"></div>