Introduction - Arduino-Mega platform

In this page we explain:

The main Arduino customization is based on Terra NET flavor for the Mega2560 platform using the NRF24L01+ radio board. Currently we tested Terra in two boards:

You will find in this page detailed information about TerraIno specific events and functions.

Installing Terra Ino in a Linux Box

Pre-requisites

Installation Steps

Install, if necessary, the following packages.

Open a command terminal and execute the following commands.

sudo apt-get update
sudo apt-get install git lua5.1 lua-lpeg nescc gcc-avr avr-libc avrdude

Adjust USB access permission for your user:

sudo usermod -a -G dialout $USER

Note: You must logout and login again to validate this new permission.

Get Terra source code from the repository

Clone Terra repository into home directory.

Open a command terminal, change to home directory, and download Terra repository.

cd ~
git clone https://github.com/afbranco/Terra

The next time use the command git pull from the new Terra dir to get last update

Create environment definitions

Open a command terminal and change to HOME directory

cd ~

Open the file .bashrc in the editor.

gedit .bashrc

Insert following lines at the end of the file.

# Export Terra paths
export TERRADIR=$HOME/Terra
export CLASSPATH=$TERRADIR/TerraControl/tinyos.jar:.$CLASSPATH

# Tools alias
alias terrac='$TERRADIR/terrac/terrac -I$TERRADIR/TerraVM/src/TerraDefs'
alias ttool='java -jar $TERRADIR/TerraControl/TControl.jar'
alias sf='java net.tinyos.sf.SerialForwarder'

Open a new command terminal to get the new environment.

Compiling and flashing

After a successful installation, you can generate a compiled file and flash it into an Arduino Mega board.

Terra development environment uses a Make system to build and install the firmware. You must change to the $HOME/Terra/TerraVM/src directory and execute make mega command with additional parameters.

The follow command is an example of Terra compilation for Arduino Mega board:

make mega TYPE:BOTH VM:NET MOD:MSGQ USB:/dev/ttyACM0 BS_BAUD:19200 install.4

Attention points

We must pay attention for some details when compiling and installing Terra for Arduino Mega.

The TYPE:type parameter indicates if your node will communicate via USB interface (BOTH) or not (NOBS). Usually one node, acting as BaseStation or sink node, is connected to a computer via USB interface when the all nodes communicate via radio. Hybrid networks may create a bridge connecting two node with different radios via serial/USB interface.

The BS_BAUD:value configures the USB baud rate for Terra operation. (This does not change the firmware flashing baud rate that is configured internally in the system.)

The INSTAL.n parameter indicates to flash the compiled file. The n is the unique node identifier for its network.

The real node address is the combination of the Network ID and the unique node identifier. For example, the default Network Id for the NRF24 network is the number 3. The node address, considering the unique ID 1, will be (3*2048)+1 = 6145.

The USB:path identifies the USB connected to flash the Mega Board. This value is usually /dev/ttyACM0 or /dev/ttyUSB0, this depends on the FDDI chip used in the board. But its number may change if the previous connection is already allocated. Use the command ls /dev/ttyA* or ls /dev/ttyU* to find the correct port.

The INO_RADIO:radio defines the radio board used in the node. Only the NRF24 value was fully tested in the last Terra version. Use the option NO_RADIO in the case you are not using a radio board, i.e. your Arduino Mega communicates only by the USB interface.

The INO_TOOLS_PATH: defines which avr-gcc installation will be used. In general you don't need to use this option, the default value points to the GNU/AVR installation. If you desires or needs to use the Arduino installation compiler, you have two options:

Terra compilation parameters

These are the allowed parameters when compiling for Arduino Mega board. The command make help mega will show an updated definition.

Compiling a Terra script

Terra scripts rely on a definition file targeting a specific customization. In the case of Arduino, the TerraIno.defs file is the the basic customization. This file must be referenced in the beginning of your script code as #include "TerraIno.defs".

Use the terrac command to compile your script. Assuming that the name of your script file is myScript.terra, type the following command:

terrac myScript.terra

This command will generate a bytecode file named myScript.vmx

Loading a Terra Script into network

Considering that you already have a script compiled with terrac compiler, you need to load the script bytecode into the Terra network nodes. Two tools must be started to that: The TinyOS SerialForwarder application and the Terra Control tool.

The use of the Terra Control tool was explained in the Terra tutorial at Terra Site. The tool can be started by the ttool command. After started, the tool waits for the SerialForwarder to connect to the USB.

The SerialForwarder is started by sf -comm serial@path:baud command, where path is the path to the USB interface and baud is the baud rate indicated in the BS_BAUD parameter. 

sf -comm serial@/dev/ttyACM0:19200

Connecting NRF24L01+ to Mega Board

The next figure shows the NRF24L01+ pin-out and the table shows the connections for Arduino Mega and MegaCore.

NRF24L01+ image
NRF24 Arduino Mega MegaCore
1 - GND GND GND
2 - VCC 3.3v 3.3v 3.3v (external)
3 - CE Digital pin 11 PB5
4 - CS Digital pin 10 PB4
5 - SCK Digital pin 52 PB1
6 - MOSI Digital pin 51 PB2
7 - MISO Digital pin 50 PB3
8 - IRQ Digital pin 2 PE4