The WiStick by Sigalabs
What is WiStick?
read their blog text.
The WiStick is a microcontroller board based on ATMEGA32u4, runs at 3.3V and 8MHz.
It has 14 digital input/output pins, 6 analog inputs, a hardware serial port (UART), a USB interface, working independent from the serial port (we use this for programming and debugging purposes), mounting holes for pin headers and screws.
It has a Li-Po JST 2-pin battery connector that you can use to power the board and a very sophisticated charging IC with auto power source selector.
Best of all, we will load it with Arduino bootloader so you can start working with it in a familiar way!
Sophisticated charging circuit
This is a new generation of charging IC’s that is a great choice if you want the battery to work as a backup power source to your system. Let’s say you have an external voltage connected to the board, the charger will disconnect the battery from the main system and charge it.
The board will be powered from the external power source without wasting the battery’s energy and life. That means no charging cycles are spent. If the system need’s instantly more power than the external source can provide it will automatically balance it taking both power from battery and the external source to satisfy the board needs. Also if the external power is cut-off it will automatically switch to battery use.
All these procedures leads to a simple result, to keep the board up and running all the time and extend the battery life and charging cycles to the maximum.
Of course a connection to the battery is not required, we can only work it on external power all the time!
Wireless Communication Interface
What will be WiStick without the “Wi” thing, right? We want the board to have minimum cost and maximum functionality, so we have chosen the most popular, available, low cost and trusty RF module existing today. This is the Nordic nRF24L01+ !
Yeap, you have seen it around and yes it’s as good as they say!
Now you may ask, why it is not integrated on the board but we are using a nasty header instead?
Well i can give you two good reasons; firstly, the cost of a small RF module based on nRF24L01+ shipped from China is unbeatable! The Mouser, a major distributor in EU, have these for 3 euros each, without calculating the cost for RF antenna and RF optimization.
Secondly, we want to make this board as modular as possible, so if in the future there is a better RF module or if you want to choose between a low cost PCB antenna module or a long-range high power with external SMA connector, you can have this extensibility easily.