21 March 2014 @ 20:27 
This race that lasts a thousand years
Will soon be done.
Hello World!
Yesterday and today, I kept on working with my nRF51822. On Wednesday, I had managed to do some advertising. Now I wanted to add a custom service.
First, I found a very useful and detailed PDF in the nRF51822 documentation, explaining how to build a simple LedButton service. Another device can write a characteristic to switch on or off the led, and the board notifies the other device when the button is pressed. Quite simple it looks! However this basic service requires a lot of code to work. So today I finished a first complete version, which has the good property to be compilable!!
But the hardest part was to actually test the program. I needed another BLE device to display the list of the services, and to read or write some characteristics. Unfortunately, I couldn’t make the Bluetooth dongle work on Linux (I tried everything Yann explained later in his post, but without success). I also tried to use a BLE scanner app on Lauriane’s Nexus 4, but the behaviour was a little unpredictable (it’s a kind of magic…): for example, I had to restart the phone in order to refresh the service list… Then I tried my program with a Nexus 5 (thanks Thomas!). Unfortunately, the behavior was also kind of magic: this time, I managed to get a notification from the board, but it happens once out of ten tries. So tomorrow I will try with another device, perhaps a Windows computer with the Nordic debug software installed on it (yeah I’m hopeless…).
May the force be with you!
Have you tried nRF Master Control Panel on Android?
Yes this is the app I used on the Nexus 5. This is the one that worked the best (I managed to get a notification with it), however there are often “Gatt Error” and I don’t know yet if it comes from my program or the Android BLE stack. That’s why I would like to try with another device.