This is my second version of the curling training stopwatch. The major improvements in comparison to the older version are: better power management, stable software and new control function.
The new system has two photocells, where the master of the system is the stop one. The start photocell is a slave, like the other module. There are two ways to show the information from the system: first one with a smartphone connected via Bluetooth to the Stop photocell. The second one is a dedicated slave module (like the Start photocell) where the communication between modules is made with a nRF24l01 (I use the version with pa+lna). In my redesign I only updated the software of my old display module but I didn’t do any other change because I chose to develop a better Android app to show the information.
Communication between photocells
The first version of my code used the TMRh20 RF24 library for Arduino. That was OK but the communication between more than 2 elements is more complicated. So I decided to use on top of this library another library to simplify the read and write between elements. The second library is the RF24G, it manages and simplifies the communication between up to 6 nodes. Now you don’t need to open/close the pipes before writing/reading.