This App Note describes how to implement a web temperature dashboard for Arduino Ethernet. It is intended to show you how the Memory-Map concept works in the practice and the way in which it can help you to improve your Arduino projects with some few simple modifications.
The system shown consists of an Arduino with a temperature sensor (eg. a LM134 lineal temperature sensor IC) connected to the NearBus Connector through internet to display the temperature value in a graphical way using the Google Spreadsheet Web App (as shown below).
How does it work?
As detailed in the overview section the NearBus system has two working modes, the VMCU (virtual microcontroller unit) mode and the TRNSP (transparent) mode. In this example we are going to use the TRNSP mode.
Under the TRNSP mode the NearBus system works replicating two groups of 8 registers each (Reg_A and Reg_B) in a periodic way :
Reg_A: Data sent from Microcontroller to the Cloud.
Reg_B: Data received in the Microcontroller from the Cloud.
In others words, the TRNSP mode can be understood as a RPC (Remote Procedure Call) or function call, that you make in your Arduino code to execute it in the cloud (as a spreadsheet formula or script), obtaining a result, and then using it in your Arduino code.
The most powerful feature of NearBus is the extremely easy way in which this complex process can be achieved. Including a single line in your code (a function call) you will be able to synchronize the register blocks (8+8) with the Google Cloud and then access them from a simple spreadsheet table (2 rows 8 cells).
So, under the TRNSP mode, changing a value in the spreadsheet replicates this value in the Arduino's memory (and vice versa) in a periodic way.