WEEK 14 - EMBEDDED NETWORKING AND COMMUNICATIONS

INTRODUCTION

STEPS PERFORMED:

• 1 x FR1 (Copper PCB Board).
• 1 x 1/64 inch end mill bit.
• 1 x 1/32 inch end mill bit.
• 1 x double tape.
• 1 x Modela MDX-20 (More about the Machine can be found in THIS LINK
• 1 x Soldering Station.
• soldering wire
• AVO multimeter
• Electronic Components (for each board, notice that we will need 2 boards. One to send and one to receive) Including:
• 1 x ATTiny45-SSU.
• 1 x (2x3) pin header for AVRISP
• 2 x Female (1x6)pinheader for Rx,Tx,VCC,GND and for the HC-05
• 1 x 1 uF Capacitor.
• 1 x LED.
• 1 x 499 Resistor.
• 1 x HC-05.

• I decided to use Autodesk Eagle as a CAD tool to design the circuit, I followed the same steps that I performed in WEEK 7 electronic design assignment.
• I opened EAGLE: I created a new project then I created a new a new schematic and I [erformed the following] :
• I added the ATTINY45, LED, 1 Micro Farad Capacitor, headers and 499 Ohm Resistor.
• I connected the components as shown below.

• I then switched to the board view by going to the top menu > File > switch to board. The board view will open up and components we just added will appear
• Use "move" to move each component around and "route" to route each trace. The wire will turn red as you route it into place.
• Keep moving and adjusting the wires and components till you reach the final desired layout as shown below.

• After I finished the orientation and wiring the components in the board view I started to do the design check also known as DRC. the main purpose of te DRC is to ensure that the used 1/64 inch mill-bit tool will have enough clearance to mill around the traces and in-between them.
• a mill-bit with the diameter of 1/46 inch (~16 mil) is used; So I opened the DRC from The "Tools" menu. Then in the "Clearance" tab, I wrote "16mil" to all the fields there.

• Finally I started to export the circuit to PNG image and I edited them using GIMP to create the TRACES PNG FILE and BORDERS PNG FILE and I performed the following steps:
• I opened GIMP, I opened the file I exported from Eagle and then I used the "Rectangle Select" tool, I selected the inner border of the dimension rectangle and then right-click->Image->Crop To Selection.
• To add a border, I clicked Image->Canvas Size and added 20px to width and height and the clicked on the "Center" button. Then to make the border white, I clicked Image->Flatten Image. Then saved the image.
• I created a new layer and I copied to it all the through-hole circles.
• In the main layer I used the "Bucket Fill Tool", I blackened all the traces so that I'm left with only a white border and I inverted the color to get white borders.
• I went back to the layer where I created through-hole circle and I colored them whith black color.
• I exported the created files as PNG, Now we are ready for milling.

• I started milling the circuit PCB board on the Modela MDX-20 using Fabmodules and soldering the components follwoing the same principles we learned in WEEK 5

• For milling the traces:
• I used the 1/64 inch diameter end mill
• cutting depth = 0.25 mm
• number of offsets = 4
• For milling the borders:
• I used the 1/32 inch diameter end mill
• cutting depth = 0.25 mm
• cutting depth = 0.6 mm

• I then started the milling as shown in hte video below

• When I created my board, I soldered the electronic components in the PCB circuit as shown below

• To add the MASTER and SLAVE configuration to the HC-05 modules, you need to enter in AT command
• I connected the HC-05 module to the ARDUINO UNO board as shown below.

• I performed the following steps to Enter the "AT MODE":
• Disconnect the +5v line from the modules end.
• Press and hold the small button on the bottom right of the HC-05 board (DO NOT RELEASE IT!)
• Reconnect the +5v connection
• Now Release the switch. Notice that the led on the module starts blinking once every two seconds, slower than normal disconnected mode.
• Upload the code below to the Arduino.

• Open up the terminal hit AT and check if the module echos back OK!.
• I executed the following AT commands to change the HC-05 default configuration:
• AT+RMAAD : Clears any previously paired devices
• AT+ROLE=0 : Sets the device to slave mode.
• AT+RESET : Resets the module, required after changing the previous settings.
• After this reset, your module may revert from AT command mode, so you will need to go through the process to set it in command mode again.
• AT+CMODE=1 : Sets the CMODE to allow connection to any device.
• AT+PSWD=1234 : Sets the password to 1234 which should be set the same on the slave device
• AT+INIT: Start Serial Port Profile, it may return error(17) which just means it’s already loaded
• AT+ADDR?:we will get back the address of the Bluetooth module and it should looks something like this: 98d3:34:905d3f.

• similarly, connect the master hc-05 and Open up the terminal hit AT and check if the module echos back OK!.
• I executed the following AT commands to change the HC-05 default configuration:
• AT+RMAAD : Clears any previously paired devices
• AT+ROLE=1 : Sets the device to master mode.
• AT+RESET : Resets the module, required after changing the previous settings.
• After this reset, your module may revert from AT command mode, so you will need to go through the process to set it in command mode again.
• AT+CMODE=0 : (To connect the module to the specified Bluetooth address and this Bluetooth address can be specified by the binding command).
• AT+BIND=xxxx,xx,xxxxxx : (Now, relace the XXXXXXXXX with your respective address to the slave. Note the commas instead of colons given by the slave module).
• AT+PSWD=1234 : Sets the password to 1234 which should be set the same on the slave device
• AT+INIT: Start Serial Port Profile, it may return error(17) which just means it’s already loaded

• For each of the MASTER and SLAVE: I connected the HC-05 to the Arduino as shown in the fiagram below and I uploaded the code below (same Code I used for the AT mode configuration)

• I connected each Arduino to a different laptop and I opened serial monitor in the ardiono IDE in each of them.
• Both the MASTER and SLAVE HC-05 boards LEDs started to blink rapidly then once they got paired the blinking started to be slower (almost 2 blinks 1 sec apart).
• I typed a digit in Serial monitor input in the laptop connected to the MASTER board -> The digit appears in the Serial monitor in the laptop connected to the SLAVE board.
• I typed a digit in Serial monitor input in the laptop connected to the SLAVE board -> The digit appears in the Serial monitor in the laptop connected to the MASTER board.
• This can be shown in the video below.

• Connect the FAB ISP pins to my board pins with each pin connected to its corresponding similar pin as follows:
• MISO (in FAB ISP) -> MISO (in Bluetooth Board)
• MOSI (in FAB ISP) -> MOSI (in Bluetooth Board)
• SCK (in FAB ISP) -> SCK (in Bluetooth Board)
• Vcc (in FAB ISP) -> Vcc (in Bluetooth Board)
• GND (in FAB ISP) -> GND (in Bluetooth Board)
• RST (in FAB ISP) -> RST (in Bluetooth Board)
• Connect the FAB ISP to the usb Port and ensure it is detected by the PC.
• Connect the FTDI Cable to the FTDI header in the FTDI pins in the Bluetooth Board.

• open arduino IDE then burn the BOOTLOADER.
• To burn the BOOTLOADER I followed the following steps:
• Select "USBTinyISP" under Tools > Programmer.
• Select ATtiny from Tools > Board.
• Select the specific ATtiny you are using (44/45/84/85) from Tools > Processor.
• Next select "16 MHz (INTERNAL)" from Tools > Clock.
• select "Burn Bootloader" under tools and wait till it complete.

• I looked at the ATTINY45 Datasheet and the PINOUT map in the diagram below to identify the ARDUINO mapping of the Attiny45 pins

• I assigned in each of the 2 boards the PINS as follows:
• Bluetooth RX -> PIN 1 (Physical ATTINY45 PIN 6) and Bluetooth TX -> PIN 2 (Physical ATTINY45 PIN 7)
• ATTINY45 LOCAL RX -> PIN 3 (Physical ATTINY45 PIN 2) and Bluetooth TX -> PIN 4 (Physical ATTINY45 PIN 3)
• LED PIN -> PIN 0 (PHysical ATTINY45 PIN 5)
• I connected each of the 2 boards to FTDI cable and HC-05 module as shown in the connection diagram below.

• I wrote the following code for the MASTER and below are few notes about the code:
• I initiated the code and I made the board write to the ATTINY Software Serial a sentenc to declare that this is the MASTER module.
• I programmed the board to listen to any input coming from the ATTINY Serial and Once a character is received to direct it / Write to the Bluetooth Software Serial (AKA in this code as EEBlue).

• I initiated the code and I made the board write to the ATTINY Software Serial a sentenc to declare that this is the SLAVE module.
• I programmed the board to listen to any input coming from the HC-05 Serial and Once a character is received, it checks the character value:
• If Value = 1 -> It print "1 Received" to acknowledge it received 1 and it Turn ON the LED
• If Value = 0 -> It print "0 Received" to acknowledge it received 0 and it Turn OFF the LED

• I compiled the code then I uploaded it.

• BOARD EAGLE SCHEMATIC FILE.
• BOARD EAGLE BOARD FILE.
• BOARD TRACES PNG FILE.
• BOARD OUTLINES PNG FILE.
• SKETCH TO SET AT COMMANDS.
• MASTER .INO FILE.
• SLAVE .INO FILE.