The purpose of this assignment was created networking between computer and boards using the example of serial bus. The bridge board was connected to a computer via a FTDI cable. The two node boards were connected to the bridge board using a connector.

For this example I used two node boards, but was possible to connect multiple nodes.

I used 1 hello.bus.45.bridge and 2 hello.bus.45.node. Components for each board:

- 6 pin header

- 4 pin header

- FTDI header ( just for the Bridge Board to connect to computer)

- Resistor 10 K

- Resistor 1 K

- Capacitor 1 uf

- Microcontroller Attiny45

- LEDs

I downloaded and used the hello.bus.45.c code ( and makefile) proposed in the schedule of Fab Academy week. Each board was programmed individually, to do this I modified the C code for each board:

- Each node needs to have a different node ID number (0, 1, 2, 3, etc). The "bridge" board is also a "node".

- In the C code, I changed the line:#define node_id '0' and I saved the file.

- I connected the bridge board to computer with the FTDI header and I programmed it using the FabISP, I flashed the bridge board as node 0: sudo make -f hello.bus.45.make program-usbtiny

- Next, I modified again the C code and changed the node ID to 1:#define node_id '1' and I saved the file.

- I used the bridge board to power node boards and connect them to TX and RX. Then I flashed the node board as node 1: sudo make -f hello.bus.45.make program-usbtiny

I Repeated this process for node 2.

After flashing boards whit 3 different node numbers:

- I Plugged the bridge Board into computer (FTDI cable);

- I Connected the nodes with 4 pin header (Tx,Rx,Vcc,Gnd);

- Open a Arduino IDE and the serial monitor;

- Make sure the baud rate is set to 9600;

- Enter number of a note (pick a number) into serial monitor - press the key or the "send" button on the serial monitor;

- The LEDs on all the boards lighted up once;

- After all the boards lighted up, the board with the number entered into the serial monitor lighted up again;

- The node name (node 0, node1, node2) also was displayed on the serial monitor.

The first time I programmed the boards at low speed (I tried to 1 Mhz), but in the serial monitor I could not read anything. I increased the programming speed at 8 MHz and I fixed it.

To read better the lighted up of LEDs, I changed the delay in the C code from 100 ms to 1000 ms: #define led_delay() _delay_ms(1000) , I saved the file and re-programmed all the boards.

I had a lot problems with noise of node 2 . When I used the Arduino serial monitor the node name displayed was “strange” and each time different. I controlled the board and solder, I changed the connector and rolled the wires to reduce the interference, but I just reduced the noise. I could not fixed completely this problem.

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