Arduino | Sony Arouje

Posts Tagged ‘Arduino’

Digital I/O Expander for Arduino

When we work with processor like Amega328 or ATTiny85 we will come to a situation like we are running short of GPIO pins. One option is to go for 40pin processors like Atmega16/32/324, etc. But there are some cons with 16/32, these chips doesn’t have PCINT (Pin change interrupt) and we cant use software serial. If we are not dealing with Software serial then we can use these MC’s without any issues. Some of the experiments I am doing, deals with Software serial, so I decided to use Atmega328. But I need more Digital I/O pins. To get more IO we can pair Atmega328 with GPIO expanders like MCP23017 or MCP23S17.

Keep in mind that MCP23017 talks via I2C and MCP23S17 talks via SPI. I prefer I2C as it uses two pins of my Arduino, SCL and SDA. SPI needs 4 pins, MISO, MOSI, SCK and RESET. Also in my system there are several other chips connected to I2C bus and thus deals with only one type of communication.

Lets see how to connect MCP23017 to Arduino

MCP23017 Pinout

As you can see we have 16 GPIO’s in MCP23017, 1-8 and 21 to 28.

Connection

5v to pin 9
GND to 10.
Arduino SCL to pin 12
Arduino SDA to pin 13.
MCS23017 RESET pin to pin9 with a 1k Resistor.

Now we need to set the I2C address of this pin. You can connect upto 8 MCP23017 by changing connection to A0 to A2 (pin 15 to 17). For e.g. connect all three pins to GND will get an address of 0, connect A0 to VCC and A1 and A2 to GND will give an address of 1 and so on.

Here I am connecting all the pins to GND and I get an address of 0.

Schematic

Here I am not detailed the connection to Atmega328. I focused on the connectivity between 328 and MCP23017. To see how to run an Atmega in standalone mode, check this post.

Edit: As Anon suggested in comments sections, I added a pullup resistor to SDA and SCL lines. I2C is open drain and without a pullup resistor the system will not work.

Arduino Sketch

I used Adafruit library to interact with MCP23017, you also can directly interact with expander by just using wire library. There is a good post explaining how to write data to MCP23017 without any library.

#include <Wire.h>
#include "Adafruit_MCP23017.h"


Adafruit_MCP23017 mcp;
void setup() {
  mcp.begin(0);
  mcp.pinMode(1, OUTPUT);
}

void loop() {
  delay(1000);
  mcp.digitalWrite(0, HIGH);
  delay(1000);
  mcp.digitalWrite(0, LOW);
}

Here port 0 is referring to pin 21.

Here I talks about I2C connectivity but you can also use SPI using MCP23S17.

These expanders are not limited to Atmegas we can use it with Raspberry pi’s or any other processors that supports I2C or SPI communication.

Happy hacking…

Written by Sony Arouje

June 14, 2016 at 10:41 am

Posted in Arduino

Tagged with Arduino, GPIO Expander, MCP23017

Control AC/DC devices using Arduino

Connect Arduino to external EEPROM

Bluetooth Communication with Arduino

Farm Automation system based on Arduino and Raspberrypi

with 3 comments

Last two weeks, in my free time, I was working on a system to automate Green house or an open field. The system designed using Arduino Nano and Raspberry Pi. The Arduino is used to read sensors and control devices and the Raspberry pi is the brain that decides what to do when an event detected by Arduino. All the systems communicates wirelessly via XBee.

In normal scenario in a farm we have to

Switch on the drip irrigation pump when the soil humidity is low.
Switch off when the soil is wet.
Switch on the Main motor that connects to a water source when the reservoir level goes down.
Switch off the main motor when the reservoir is full.
If it’s a Green house then monitor the humidity and control devices to increase or decrease the humidity. Also need to control temperature.

Below is a very ugly drawing I could come up : ), to explain the system.

Arduino based nodes

The nodes are connected to different Sensors like Soil Humidity, Temperature, Air Humidity, etc. Also the nodes can also switch on/Off drip irrigation motor, switch on/off Reservoir’s Solenoid valves, or control any hardware needed in the field.

Raspberry pi Brain

I developed this central/brain system in Nodejs. The system is very much generic and run based on configurations. So nothing is hardcoded. The XBee connected to the pi act as the coordinator and receive periodic sensor inputs from Ardunio connected in the field. This system can issue command to control devices based on the sensor inputs.

Let’s go through some of the scenarios to see how the system works.

Watering the plants: From the above picture you can see, there are 5 Arduino’s in the field sensing different parameters. For now lets think that they all reads the soil humidity. Say soil humidity value range from 0 to 100, where 0 is dry and 100 is fully wet. We need to switch on the drip irrigation motor when any of the sensor value is less than 20. Once all the sensor give a humidity value greater than 90 we need to switch off the motor.

As you can see the system need to take action based on the values coming from the sensor. Depending upon the crops these values can be changed. That’s where the Central Node js system comes into play.

In the central system, we can group the Sensor nodes and configure the triggering points. Also we can configure what to do when the triggering points reach. For e.g. in the above case we can say when the soil humidity of any sensor goes below 20, then send the Motor switch on command to the node sitting next to the Reservoir motor. To switch off the motor, the system needs approval from all the sensors, that means the motor will get switched off if all the nodes reported value is greater than 90.

Failover: What happens when a sensor node dies without sending soil humidity greater than 90 value, will the motor run whole day? No, the central system can be configured for that too, while configuring we can set up a timeout period. If the central system is not receiving high water level after a configured time, it automatically sends a Switch off command to the desired Arduino node to switch off the motor.

Filling Reservoir: From the above diagram, we can see there are two reservoirs and one Main motor. The main motor need to switch on to fill the Reservoir. Each reservoir is equipped with sensors to detect the High and Low water level. Also each water input is equipped with a solenoid valve. If the reservoir is high then the solenoid valve will close the input thus protect the reservoir from overflowing. Once all the reservoir get filled the system will switch off the Main motor before closing the last solenoid, other wise the pressure increase and can damage the Main motor.

The Arduino node will send a Water low when the water go down below a desired level. Then the central system will open the Solenoid before switching on the Main motor. The valve will open only for the reservoir where the water is low, rest all the valves will be closed.

If more than one Reservoir’s water is low then those valves will be open and the main pump will work until all the reservoir’s are filled. For e.g. say Reservoir A and B’s water level is low then both the valves will be open and switch on the main pump. A get filled and B is still not full then A’s valve will get closed. Once B is full the system will send Main pump switch off command then sends the command to close B’s valve.

System design

All the above scenarios are based on certain rules and all these rules are configurable. The central system is not aware of any rules. Based on the fields condition we need to configure it.

User can also see the activities in the farm via a dashboard. I haven’t designed any Dashboard UI yet.

Happy farming…

Written by Sony Arouje

February 17, 2016 at 6:16 pm

Posted in Arduino, Raspberry Pi

Tagged with Arduino, Farm Automation, raspberry pi, XBee

Communication between Raspberry Pi and Arduino using XBee

with 18 comments

Recently I was doing some experiments to establish a wireless communication between a Raspberry pi and Arduino. To establish wireless communication I used XBee Pro Series 2 from Digi International. The idea behind this test setup is to test, whether I can control devices like motor or read different sensors remotely.

One of the biggest advantage of using XBee is, you can find a lot of tutorials and libraries for any kind of system and programming languages. For this test app, I used Node js in RPi and C in Arduino.

Test Setup

XBee: I configured two xbee, one as Coordinator and another as Router. Both in API mode 2 (AP =2). I used XCTU to configure both the device. Only reason to choose API 2 is because the Arduino library I used only support API mode 2.

Raspberry pi: connected Coordinator XBee to one of my RPi. You can see more about the connection in one of my earlier post.

Arduino Uno: connected the Router xbee to one of my Arduino. The connection is pretty simple as below.

XBee Rx –> Arduino Tx
XBee Tx -> Arduino Rx
XBee 3.3v-> Arduino 3.3v
XBee Gnd –>Arduino Gnd

Raspberry Pi Node js code

Modules used

xbee-api: npm install xbee-api
serialport: npm install serialport

var util = require('util');
var SerialPort = require('serialport').SerialPort;
var xbee_api = require('xbee-api');

var C = xbee_api.constants;

var xbeeAPI = new xbee_api.XBeeAPI({
    api_mode: 2
});

var serialport = new SerialPort("/dev/ttyAMA0", {
    baudrate: 9600,
    parser: xbeeAPI.rawParser()
});

var frame_obj = {
    type: 0x10,
    id: 0x01,
    destination64: "0013A200407A25AB",
    broadcastRadius: 0x00,
    options: 0x00,
    data: "MTON"
 };

serialport.on("open", function () {
    serialport.write(xbeeAPI.buildFrame(frame_obj));
    console.log('Sent to serial port.');
});

// All frames parsed by the XBee will be emitted here
xbeeAPI.on("frame_object", function (frame) {
    console.log(">>", frame);

    if(frame.data!== undefined)
       console.log(frame.data.toString('utf8'));
});

Arduino Sketch

This sketch uses a XBee library, to add the library, goto Sketch->Include Library->Manage Libraries. From the window search for XBee and install the library. I am using Arduino IDE 1.6.7.

I use SoftwareSerial to establish serial communication with XBee, Pin 2 is Arduino Rx and Pin 3 is Arduino Tx.

#include <Printers.h>
#include <XBee.h>
#include <SoftwareSerial.h>


unsigned long previousMillis = 0;
const long interval = 4000;
// the interval in mS 
XBee xbee = XBee();
// XBee's DOUT (TX) is connected to pin 2 (Arduino's Software RX)
// XBee's DIN (RX) is connected to pin 3 (Arduino's Software TX)
SoftwareSerial soft(2,3);// RX, TX
Rx16Response rx16 = Rx16Response();
ZBRxResponse rx = ZBRxResponse();

XBeeAddress64 addr64 = XBeeAddress64(0x0013a200,0x407a25b5);

char Buffer[128];
char RecBuffer[200];
void setup() {
  // put your setup code here, to run once:
  soft.begin(9600);
  Serial.begin(9600);
  xbee.setSerial(soft);
}
void print8Bits(byte c){
  uint8_t nibble = (c >> 4);
  if (nibble <= 9)
    Serial.write(nibble + 0x30);
  else
    Serial.write(nibble + 0x37);

  nibble = (uint8_t) (c & 0x0F);
  if (nibble <= 9)
    Serial.write(nibble + 0x30);
  else
    Serial.write(nibble + 0x37);
}

void print32Bits(uint32_t dw){
  print16Bits(dw >> 16);
  print16Bits(dw & 0xFFFF);
}

void print16Bits(uint16_t w){
  print8Bits(w >> 8);
  print8Bits(w & 0x00FF);
}

void loop() {
  // put your main code here, to run repeatedly:
  
  xbee.readPacket();
  if (xbee.getResponse().isAvailable()) {
    if (xbee.getResponse().getApiId() == ZB_RX_RESPONSE) {
       xbee.getResponse().getZBRxResponse(rx);
       if (rx.getOption() == ZB_PACKET_ACKNOWLEDGED) {
            // the sender got an ACK
            Serial.println("got ACK");
        } else {
            // we got it (obviously) but sender didn't get an ACK
            Serial.println("not got ACK");
        }

        Serial.print("Got an rx packet from: ");
        XBeeAddress64 senderLongAddress = rx.getRemoteAddress64();
        print32Bits(senderLongAddress.getMsb());
        Serial.print(" ");
        print32Bits(senderLongAddress.getLsb());        
        Serial.println(' ');
        
        // this is the actual data you sent
        Serial.println("Received Data: ");
        for (int i = 0; i < rx.getDataLength(); i++) {
          print8Bits(rx.getData()[i]);
          Serial.print(' ');
        }
        
        //Received data as string to serial
        Serial.println(' ');
        Serial.println("In string format");
       for (int i = 0; i < rx.getDataLength(); i++) {
          if (iscntrl(rx.getData()[i]))
            RecBuffer[i] =' ';
          else
            RecBuffer[i]=rx.getData()[i];
        }
        Serial.println(RecBuffer);
        String myString = String((char *)RecBuffer);
        if(myString=="MTON"){
          Serial.println("Switching on Motor");
        }
        else if(myString=="MTOFF"){
          Serial.println("Switching off Motor");
        }
    }
    //clear the char array, other wise data remains in the 
    //buffer and creates unwanted results.
    memset(&RecBuffer[0], 0, sizeof(RecBuffer));
    memset(&Buffer[0], 0, sizeof(Buffer));
  }

  //Send a packet every 4 sec.
  unsigned long currentMillis = millis();
  if (currentMillis - previousMillis >= interval) {
    // save the last time you blinked the LED
    previousMillis = currentMillis;
    strcpy(Buffer,"RSLOW");
    uint8_t payload[20]= "RSLOW";

//  ZBTxRequest zbtx = ZBTxRequest(addr64,(uint8_t *)Buffer,sizeof(Buffer));
    ZBTxRequest zbtx = ZBTxRequest(addr64,payload,sizeof(payload));
    xbee.send(zbtx);
  }


}

Burn the sketch to Arduino.

Testing

Run node js code in RPi and you start receiving the frames from Arduino.

Happy coding….

Written by Sony Arouje

January 21, 2016 at 12:06 am

Posted in Arduino, JavaScript, Raspberry Pi

Tagged with Arduino, raspberry pi, Softserial, Wireless communication, XBee

Sony Arouje

Posts Tagged ‘Arduino’

Digital I/O Expander for Arduino

Control AC/DC devices using Arduino

Connect Arduino to external EEPROM

Bluetooth Communication with Arduino

Farm Automation system based on Arduino and Raspberrypi

Communication between Raspberry Pi and Arduino using XBee

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