Week 15: Networking and communications

1. Board design and fabrication
I examined the communication method. I decided to connect with I2C method. I referred to the sample board.


Since the board of Bridge has no circuit-like change, it was used in the circuit as it was. The board of Node considered the final project and changed from LED to servo motor. Cutting data was prepared as shown in the figure.


2. Board preparation
I put a boat loader on each board and succeeded. Next I wrote the servo program on Bridge's board. But it did not work. I confirmed the ATtiny 45 pin and found that the PWM signal for servo control must be connected to pin 6. Since the pattern could not be connected, it was connected with a jumper wire.



I wrote the program used during production of the output board. I was able to confirm that it works like a video.

I also made a board for LEDs to confirm the second connection. I could confirm that I write a blinking program of LED for operation confirmation.


3. Board connection
I connected two boards.I2C's program referred to Onodera's page in 2016. I used TinyWire (Donald Blake) as a library for i2c.

#include <TinyWireM.h> #include <USI_TWI_Master.h> #define SLAVE1_ADDR 1 // i2c slave address #define SLAVE2_ADDR 2 // i2c slave address #include <SoftwareSerial.h> SoftwareSerial mySerial(3, 4); // RX, TX int led_number = 0; void setup(){ TinyWireM.begin(); // init I2C Master mode, PC pinMode(3, INPUT); pinMode(4, OUTPUT); mySerial.begin(9600); mySerial.println("Hello!"); } void loop(){ if(mySerial.available() > 0){ char chr = mySerial.read(); if (chr =='t'){ mySerial.println("Tokyo Tower!!!"); TinyWireM.beginTransmission(SLAVE1_ADDR); TinyWireM.send(5); TinyWireM.endTransmission(); // Send 1 byte to the slave TinyWireM.requestFrom(SLAVE1_ADDR, 1); // Request 1 byte from slave led_number = TinyWireM.receive(); } else if (chr =='s'){ mySerial.println("Sky Tree!!!"); TinyWireM.beginTransmission(SLAVE2_ADDR); TinyWireM.send(5); TinyWireM.endTransmission(); // Send 1 byte to the slave TinyWireM.requestFrom(SLAVE2_ADDR, 1); // Request 1 byte from slave led_number = TinyWireM.receive(); } else { mySerial.println("hmm...?"); } } }

#include <TinyWireS.h> #include <usiTwiSlave.h> #include <SoftwareServo.h> #define I2C_SLAVE_ADDR 1 // i2c slave address // #define LED1_PIN 4 // ATtiny Pin 4 SoftwareServo myservo; // create servo object to control a servo int pos = 0; // variable to store the servo position int led_sta = 0; void setup(){ // pinMode(LED1_PIN,OUTPUT); // // Blink(LED1_PIN,3); // show it's alive Blink(LED1_PIN,2); // show it's alive TinyWireS.begin(I2C_SLAVE_ADDR); // init I2C Slave mode myservo.attach(1); // attaches the servo on pin 1 to the servo object } void loop(){ byte byteRcvd = 0; if (TinyWireS.available()){ // got I2C input! byteRcvd = TinyWireS.receive(); // get the byte from master Blink(LED1_PIN,byteRcvd); TinyWireS.send(byteRcvd); // send it back to master } } void Blink(byte led, byte times){ // poor man's display if(led_sta == 0){ myservo.write(0); delay(500); SoftwareServo::refresh(); myservo.write(180); delay(500); SoftwareServo::refresh(); // digitalWrite(led,HIGH); // led = 1; }else{ SoftwareServo::refresh(); delay(500); // digitalWrite(led,LOW); // led = 0; } }

As a result of the execution, it was confirmed that the character returned on the master side. However, the slave side could not write sketches due to compilation error. Onodera's page did not confirm the correspondence of the error.


4.Improve Program
Therefore, I searched for example using i2c by ATtiny45. As a result, I decided to refer to Yogi Kulkarni's page.
Quotation: Yogi Kulkarni (2016) http://archive.fabacademy.org/2016/fablabtrivandrum/students/424/w16-networking.html

On this page, I used Arudino UNO as a master. Similarly, I wrote a sketch on the master side using Arudino UNO. On the slave side, the LED flashes when communication is sent. By referring to the above page, the number of data reply counts is also counted.

master for Arudino UNO
// for Arudino UNO #include <Wire.h> void setup() { Wire.begin(); // join i2c bus (address optional for master) Serial.begin(9600); // start serial for output } void loop() { Serial.println("Requesting"); Wire.requestFrom(4, 1); // request 1 byte from slave device address 4 while (Wire.available()) // slave may send less than requested { int i = Wire.read(); // receive a byte as character Serial.println(i); // print the character } delay(1000); }

slave for ATtiny45
// Code for the ATtiny45 #define I2C_SLAVE_ADDRESS 0x4 // Address of the slave #include <TinyWireS.h> int i=0; void setup() { TinyWireS.begin(I2C_SLAVE_ADDRESS); // join i2c network TinyWireS.onRequest(requestEvent); pinMode(1, OUTPUT); pinMode(4, OUTPUT); digitalWrite(1, HIGH); } void loop() { // This needs to be here TinyWireS_stop_check(); } // Gets called when the ATtiny receives an i2c request void requestEvent() { digitalWrite(4, HIGH);�@//LED ON TinyWireS.send(i); //Count up i++; delay(2000); digitalWrite(4, LOW); }

I could communicate like the video below, and it was confirmed that the number of data transmission has been counted up. When connected to the slave side and executed it, it was confirmed that the LED flashes with count up of data transmission like video. I also tried a servo board, but it did not work. I can not analyze the cause.




Next, I changed the microcomputer on the master side to ATtiny 45 I made from Arudino UNO. A trouble occurred here. The LED board used on the slave side broke down while repeating writing. Sketch can not be written properly. Therefore, the wiring of the servo motor control board was changed so that the LED lights up.


Modified the master's program with reference to Onodera's page and Kulkarni's page. I confirmed that it works the same as when using Arudino UNO.

master for ATtiny45
#include <TinyWireM.h> #include <SoftwareSerial.h> SoftwareSerial mySerial(3, 4); // RX, TX int led_number = 0; void setup(){ TinyWireM.begin(); // init I2C Master mode, PC pinMode(3, INPUT); pinMode(4, OUTPUT); mySerial.begin(9600); mySerial.println("Hello!"); } void loop(){ mySerial.println("Requesting"); TinyWireM.requestFrom(4, 1); // Request 1 byte from slave while (TinyWireM.available()) // slave may send less than requested { int i = TinyWireM.read(); // receive a byte as character mySerial.println(i); // print the character } delay(50); }




Archive
-board circuit data (Eagle)
-servo board data (png)
-Arudino sketch (3 programs) (UNO,ATtiny45)

This week's assignment is over.