llevola

The hardness of calcite aka limestone (CaCO3) on Mohs scale is 3, same as copper.

The default for power mode in HM-10 is already not to auto-sleep, so that should not be a factor. I noticed that the Android app does not really make the bluetooth connection, but the iOS app does. This is despite both initially finding it and then reading "chronograph disconnected". The connection was evident from the HM-10 status led and it notifying OK+CONN through UART once I configured it to do so. I was able to send commands to chrono from terminal program on PC via wired UART and from Android serial terminal app via Bluetooth. But I noticed now that I don't get responses from chrono, so that might be something. Something with the wirings... HM-10 is Bluetooth LE aka Bluetooth Smart (introduced with BT 4.0) that is a requirement for function with iOS as it lacks the Serial Port Profile. I believe the connection profile in LE is Generic Access Profile. I must say I am not a professional with the BT stack, so if somebody knows more, please fill me in. I am wondering if the app expects that some attributes, UUIDs or what-not's are defined for the peripheral. So, bobdirt, the app and chrono are fully functional for you with HM-06 and Android app, is that correct?

I get the App to initially find the HM-10 bluetooth module (after named "Digital Link") on both Android and iOS. But then after going forward to the Shots list, the bottom of the screen reads "Chronograph disconnected". Baud rate was successfully changed also. What am I missing?