Quad Expansion board for the Mercury System

• Mercury Connectors #1 #2 #3 #4: to interface the board with the other boards of the Mercury family.
• BB Program&Debug Connector: PicKit 3 Microchip programmer / debugger connector. It connects directly to the debug port of the microcontroller on the BB (Base Board), to allow advanced debugging and programming functions.
• Buses Expansion: expansion connectors for the power supply and for the I2C and UART connection.
• Comm. Connector: I2C and UART communication bus connector.

The set of boards that makes up the Mercury System is made of the following “families”:

• Base Board (BB): It is the “brain” of the whole Mercury System and holds the main logic unit, several communication buses and the connectors used to interface the slaves. It also holds a simple power supply system and a charging unit for a single LiPo cell (able to meet the power requirements of simpler systems). It can exist in several variants, depending on the microcontroller unit used.

• Modem Board (MB): this is the board that provides network connectivity. It can exist in several variants, depending on the network interface (GSM / GPRS, Wi-Fi, BT, Radio …). It is interfaced to the base board with a dedicated serial line.

• Power Board (PB): this is the board that meets the particular power needs of the system, when they have to be met. They can differ according to the particular power need to be covered (high power, solar harvesting, piezoelectric harvesting, etc.).

• Slave Board (SB): these are the peripherals of the system and they vary according to the specific sensor or actuator fitted. Typical examples are SBs with relays, temperature sensors, RGB LED controllers, servo controllers, accelerometers, etc. They talk to the BB over I2C or UART with a dedicated command set.

• Expansion Board (EB): these are the boards that allow the planar connection of the Mercury boards. There are variants that can carry displays, a battery holder, etc.

• Brain-Less Board (BL): these are the boards without a controller. In general they carry really simple sensors or actuators that do not need the bus interface. They are an alternative to the slave boards for applications that have to keep costs down.

The Slave Boards and the Modem Boards come pre-programmed with firmware that implements a dedicated command set for high-level management, while the Base Boards come with a software framework that provides all the low-level services (operating system, peripheral drivers, system services, etc.), leaving the user only the development of the application-level logic.

HAL (Hardware Abstraction Layer): the purpose of this layer is to abstract the hardware dependencies away from the upper layers.
SML (System Management Layer): the purpose of this layer is to provide services for managing the communication buses (I2C, UART) and for managing the Modem Board (WiFi, BT, GSM / GPRS). It also provides a set of system services, such as System Power Management, RTCC, USB terminal, etc.
It is divided into two main components:

OSL (Operative System Layer): this layer consists of a lightweight RTOS that provides basic services to the system, such as the scheduling tables for the various tasks, events, SW timers, alarms, etc.

There are several sub-families of Slave Board:

• Sensor Slave Board
• Actuator Slave Board
• Communication Slave Board
• Interface Slave Board
• Special Slave Boards

The table below gives some examples for each sub-family:

• Mercury System Getting Started Guide IoT and Connectivity Made Simple
• MS_EB111_Datasheet
• MS_EB111_Schematic: the circuit diagram of the board.