16×2 Display Expansion Board for the Mercury System

• Mercury Connectors #1 #2: to interface the board with the other boards in the Mercury family
• Address Dip Switch: Dip switch to set the address of the board within the Mercury system.
• EB Programmer Connector: PicKit 3 Microchip programmer / debugger connector. It plugs straight into the debug MCU port of the EB (Expansion Board), for advanced debugging and programming.
• BB Program&Debug Connector: PicKit 3 Microchip programmer / debugger connector. It plugs straight into the debug MCU port of the BB (Base Board), for advanced debugging and programming.
• Display Contrast Reg.: potentiometer to adjust the contrast.
• Buses Expansion: expansion connectors for the power supply and for the I2C and UART links.

• ADC: 12 ch, 10-bit
• Comparators: 2
• Temperature range: -40°C ~ 125°C
• Operating voltage: 1.8~5.5 V
• Pin Count: 20
• XLP: yes

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

• Base Board (BB): It is the “brain” of the whole Mercury System and it carries the main logic unit, several communication buses and the connectors for interfacing the slaves. It also carries a simple power supply and a charger for a single LiPo cell (enough to meet the power requirements of simpler systems). It comes in several variants, depending on the microcontroller unit used.

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

• Power Board (PB): this is the board that meets the particular power needs of the system, when they arise. They vary according to the particular power need to be met (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 drivers, accelerometers and so on. 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 and so on.

• 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 control, while the Base Boards come with a software framework that provides all the low-level services (operating system, peripheral drivers, system services and so on), leaving the user only the application-level logic to write.

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

• PML: peripheral management layer
• SSL: system services layer

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 and so on.

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 a few examples for each sub-family:

• Mercury System Getting Started Guide IoT and Connectivity Made Simple
• MS_EB210_Datasheet
• MS_EB210_Schematic