Each Satellite has 15 digital I/O pins and 4 analog inputs. 13 digital I/O pins are usable on the Gateway. The maximum number of Satellites is 26: this means a total of 390 bidirectional I/O ports and 104 analog inputs (plus the ports on the Gateway).
Only four pins of the RPI’s GPIO port P1 are used: two for the serial port and two for the power supply.
The dialogue between the Raspberry and the Gateway is based on human-friendly ASCII strings. This very simple protocol allows the users to write their own applications in virtually any programming language.
Some of the available I/O pins can be dedicated to special functions: a pulse-counter input (for use with an energy-meter), a serial output (on the Satellites only) and 2 PWM outputs. SWiTh is also ready for temperature and relative-humidity measurements using a SHT11 or SHT15 sensor. These extra functions can be disabled, if not needed.
The Gatewy offers 13 digital I/O pins and 4 analog inputs.
Two on-board LEDs can be used to monitor the wireless communications. SWiTh can be upgraded using the built-in ICSP port.
SWiTh is a personal project. It is not open-source.
A user-guide is available upon request (mail to firstname.lastname@example.org).
Any inquiries are welcome and any suggestions will be appreciated.
SWiTh can be used with any ordinary PC.