Hardware Senslab gateway
The gateway main functionality is to get an Ethernet or Wifi communication with the Node Handler. This is done via a Digi Connect EM module (Ethernet version), or a Digi Connect Wi-EM for the Wifi version. Exact Digi references are DC-EM-02T-NC and DC-WEM-02T-C. These 2 references are pin-to-pin compatibles, allowing only one unique board design, with either an Ethernet or a Wifi module on it.
These modules embed an ARM7-based module plus Ethernet or Wifi specialized chips. 2 UARTs and 5 GPIOs are available. They are used for UART communication with the WSN430 boards, as well as Bootstrap Loader communications (msp430 firmware update).
UART multiplexing Each WSN430 board needs to be connected to two 2-wires UARTs. The first UART is the standard UART0 for msp430 communication. The second one is used for BSL operations (firmware update). Since the Digi modules have only 2 UARTs available, they are multiplexed with a simple analog mux, which is controlled by Digi module GPIO5.
Open node supply The open node can be powered either by main or battery supply. Both "supply lines" are controlled by the control node with the K1 and K2 relays. Note that the control node is continuously power supplied by the SensLAB gateway board and equipped to measure the current and voltage. 1 ohm precision resistors are used for the shunt, and measures are done with TI INA209 chips. Expected measure precision is 10uA, and power sampling around 1kHz. These INA209 chips are configured and controlled from the control node with an I2C bus.
Connectors The SensLAB gateway has five connectors :
- two 26 pins connects for connection with the 2 WSN430 boards
- one RJ45 connector (Ethernet)
- one jack connector for external power supply (if no PoE)
- one Jst connector for the open node battery