Using serial communication without pc

You're a bit confusing, serial communication means sending data on a single communication channel bit by bit, hence it's name. Usb also does serial communication as rs232 but at a way faster rates and using different protocols. You want your robot to be controlled from a computer or from a remote control? If you want to get rid of your arduino's and just use the microcontrollers (atmega328), well you can either way (pc or remote), you just have to adapt the software on both microcontrollers and setup the fuses for external clock to use without arduino boards. Here's a useful link Arduino - ArduinoToBreadboard

Thank you sir, the link was helpful. I wanted to use my arduino as remote control and receiver on the car which works without a computer. I want my robot to be controlled by a remote control. Sorry for the confusion with the serial communication, I just wanted to tell about the Serial.print and Serial.read commands.

the code i'm using is found on the adarfuit fingerprint repository library :

#include <Adafruit_Fingerprint.h>

#include <SoftwareSerial.h>

int getFingerprintIDez();

// pin #2 is IN from sensor (GREEN wire)

// pin #3 is OUT from arduino  (WHITE wire)

SoftwareSerial mySerial(2, 3); 

Adafruit_Fingerprint finger = Adafruit_Fingerprint(&mySerial);

On Leonardo/Micro or others with hardware serial, use those! #0 is green wire, #1 is white

//Adafruit_Fingerprint finger = Adafruit_Fingerprint(&Serial1);

void setup() 

{

  while (!Serial);  // For Yun/Leo/Micro/Zero/...

  Serial.begin(9600);

  Serial.println("Adafruit finger detect test");

  // set the data rate for the sensor serial port

  finger.begin(57600);

  if (finger.verifyPassword()) {

    Serial.println("Found fingerprint sensor!");

  } else {

    Serial.println("Did not find fingerprint sensor :(");

    while (1);

  }

  Serial.println("Waiting for valid finger...");

}

void loop()                     // run over and over again

{

  getFingerprintIDez();

  delay(50);            //don't ned to run this at full speed.

}

uint8_t getFingerprintID() {

  uint8_t p = finger.getImage();

  switch (p) {

    case FINGERPRINT_OK:

      Serial.println("Image taken");

      break;

    case FINGERPRINT_NOFINGER:

      Serial.println("No finger detected");

      return p;

    case FINGERPRINT_PACKETRECIEVEERR:

      Serial.println("Communication error");

      return p;

    case FINGERPRINT_IMAGEFAIL:

      Serial.println("Imaging error");

      return p;

    default:

      Serial.println("Unknown error");

      return p;

  }

  // OK success!

  p = finger.image2Tz();

  switch (p) {

    case FINGERPRINT_OK:

      Serial.println("Image converted");

      break;

    case FINGERPRINT_IMAGEMESS:

      Serial.println("Image too messy");

      return p;

    case FINGERPRINT_PACKETRECIEVEERR:

      Serial.println("Communication error");

      return p;

    case FINGERPRINT_FEATUREFAIL:

      Serial.println("Could not find fingerprint features");

      return p;

    case FINGERPRINT_INVALIDIMAGE:

      Serial.println("Could not find fingerprint features");

      return p;

    default:

      Serial.println("Unknown error");

      return p;

  }

  // OK converted!

  p = finger.fingerFastSearch();

  if (p == FINGERPRINT_OK) {

    Serial.println("Found a print match!");

  } else if (p == FINGERPRINT_PACKETRECIEVEERR) {

    Serial.println("Communication error");

    return p;

  } else if (p == FINGERPRINT_NOTFOUND) {

    Serial.println("Did not find a match");

    return p;

  } else {

    Serial.println("Unknown error");

    return p;

  }  

  // found a match!

  Serial.print("Found ID #"); Serial.print(finger.fingerID);

  Serial.print(" with confidence of "); Serial.println(finger.confidence);

}

// returns -1 if failed, otherwise returns ID #

int getFingerprintIDez() {

  uint8_t p = finger.getImage();

  if (p != FINGERPRINT_OK)  return -1;

  p = finger.image2Tz();

  if (p != FINGERPRINT_OK)  return -1;

  p = finger.fingerFastSearch();

  if (p != FINGERPRINT_OK)  return -1;

  // found a match!

  Serial.print("Found ID #"); Serial.print(finger.fingerID);

  Serial.print(" with confidence of "); Serial.println(finger.confidence);

  return finger.fingerID;

#include <Adafruit_Fingerprint.h>

#include <SoftwareSerial.h>

int getFingerprintIDez();

// pin #2 is IN from sensor (GREEN wire)

// pin #3 is OUT from arduino  (WHITE wire)

SoftwareSerial mySerial(2, 3);

Adafruit_Fingerprint finger = Adafruit_Fingerprint(&mySerial);

On Leonardo/Micro or others with hardware serial, use those! #0 is green wire, #1 is white

//Adafruit_Fingerprint finger = Adafruit_Fingerprint(&Serial1);

void setup() 

{

  while (!Serial);  // For Yun/Leo/Micro/Zero/...

  Serial.begin(9600);

  Serial.println("Adafruit finger detect test");

  // set the data rate for the sensor serial port

  finger.begin(57600);

  if (finger.verifyPassword()) {

    Serial.println("Found fingerprint sensor!");

  } else {

    Serial.println("Did not find fingerprint sensor :(");

    while (1);

  }

  Serial.println("Waiting for valid finger...");

}

void loop()                     // run over and over again

{

  getFingerprintIDez();

  delay(50);            //don't ned to run this at full speed.

}

uint8_t getFingerprintID() {

  uint8_t p = finger.getImage();

  switch (p) {

    case FINGERPRINT_OK:

      Serial.println("Image taken");

      break;

    case FINGERPRINT_NOFINGER:

      Serial.println("No finger detected");

      return p;

    case FINGERPRINT_PACKETRECIEVEERR:

      Serial.println("Communication error");

      return p;

    case FINGERPRINT_IMAGEFAIL:

      Serial.println("Imaging error");

      return p;

    default:

      Serial.println("Unknown error");

      return p;

  }

  // OK success!

  p = finger.image2Tz();

  switch (p) {

    case FINGERPRINT_OK:

      Serial.println("Image converted");

      break;

    case FINGERPRINT_IMAGEMESS:

      Serial.println("Image too messy");

      return p;

    case FINGERPRINT_PACKETRECIEVEERR:

      Serial.println("Communication error");

      return p;

    case FINGERPRINT_FEATUREFAIL:

      Serial.println("Could not find fingerprint features");

      return p;

    case FINGERPRINT_INVALIDIMAGE:

      Serial.println("Could not find fingerprint features");

      return p;

    default:

      Serial.println("Unknown error");

      return p;

  }

  // OK converted!

  p = finger.fingerFastSearch();

  if (p == FINGERPRINT_OK) {

    Serial.println("Found a print match!");

  } else if (p == FINGERPRINT_PACKETRECIEVEERR) {

    Serial.println("Communication error");

    return p;

  } else if (p == FINGERPRINT_NOTFOUND) {

    Serial.println("Did not find a match");

    return p;

  } else {

    Serial.println("Unknown error");

    return p;

  }  

  // found a match!

  Serial.print("Found ID #"); Serial.print(finger.fingerID);

  Serial.print(" with confidence of "); Serial.println(finger.confidence);

}

// returns -1 if failed, otherwise returns ID #

int getFingerprintIDez() {

  uint8_t p = finger.getImage();

  if (p != FINGERPRINT_OK)  return -1;

  p = finger.image2Tz();

  if (p != FINGERPRINT_OK)  return -1;

  p = finger.fingerFastSearch();

  if (p != FINGERPRINT_OK)  return -1;

  // found a match!

  Serial.print("Found ID #"); Serial.print(finger.fingerID);

  Serial.print(" with confidence of "); Serial.println(finger.confidence);

  return finger.fingerID;

It should make no difference if the PC is connected or not, the hardware serial (Pin 0 and 1) will still flicker one of the LEDs as it will still transmit to the USB controller. it just won't receive serial data from the PC or ultimately send serial to the PC from the USB interface. For the fingerprint reader you're using a software serial on separate pins (2, 3)

What is my first thought is that the power is affecting it. When the PC is connected your providing 5V nominal through the USB port and everything is working from this

What is the battery voltage and where are you connecting it, you should be connecting something like 6-9 V on the barrel connector, 5V via a USB lead or the 5V pin on the headers. or 6-9V via the header pin marked Vin.

Please provide this info

Hi Mr. Oakes,

The problem is that neither of the led lights signalling Rx and Tx communication flicker when the system is not connected to a laptop.

I think thats the part I'm having most trouble figuring out.

With the voltage supply, I have tried both the barrel connector for the 9v battery as well as connecting the 9v battery supply into the Vin pin. I get the same response from both.

I also tried checking to see if the battery was supplying enough voltage as per the fingerprint scanner requirement.

Using a multi meter, I established that the fingerprint scanner was indeed receiving between its allowed range of 3.66- 6 V.

It was on these grounds that I ruled out a problem with the electrical set up.

What are your thoughts?

Do you think it could still be a problem with the power supply?

I just checked with a sketch

The serial lights TX or RX do not flicker when the USB is not connected, you can see that the USB Controller knows when the USB is connected and also that the lights are controlled by the USB controller, not the ATMEGA328

SO this is not a worry.

Back to your sketch, what makes you think it is not working (Aside from the TX/RX LEDS not doing what you expect.)

Hi Mr. Oakes,

Okay, that helps clear some things for me. Thank you

Actually, I wouldn't know then.

The thing is, the lights of the scanner behave very differently the second they are disconnected from computer. They are slightly dimmer and more often.

I spoke to someone from technical support, who mentioned that the lights on the scanner are dictated by certain commands in the code.

Would you have any idea in mind as to how I could check the functionality of the fingerprint scanner without the serial monitor?

Again, I really appreciate your help here. It was heartening to note that there are very nice people out there to help out!

To add on, ( not sure if i mentioned already )the lights are dimmer and its flickers more often when the system is connected in the absence of the computer.

Also when the enrolled finger is placed, there is no change in the blinking activity, as it did when it was connected to the laptop

Would that be an indication of crippled functionality?

Or do you think it might be working, but required a bit of tweaking to the code.

I tried using leds as an indicator to idenitfy what was happening along the way.

I placed the digitalwrite (led, HIGH) command after the conversion process. I then turned out the led after the fingerprint was matched

this worked perfectly with my code.

But when I disconnected it from the laptop, the leds didnt work anymore either. So i'm guessing nothing is really happening inside?

How were yo planning on using the scanner in the original design without the PC ?

Suggestions would be

LCD Display either attached via I2C or even via the hardware serial port but connected to pins 0,1 (You would need to disconnect during programming only. (A NExtion Display here would work great , see my video here:- https://www.youtube.com/watch?v=3AT92tZ4knU for an example

LED display

What was your plan ?

This may be too simplistic, but t sounds as if your Arduino is struggling/failing to operate on your external PSU.

Try uploading the "Blink" sketch and see if that will run when the Arduino is connected to USB and then when connected to your external PSU.

Hope this helps

Neil

This may be too simplistic, but t sounds as if your Arduino is struggling/failing to operate on your external PSU.

Try uploading the "Blink" sketch and see if that will run when the Arduino is connected to USB and then when connected to your external PSU.

Hope this helps

Neil

hi Neil,

you were spot on. I think I've been using a battery of insufficient amperage. Should be sorted now.

Thanks a ton, man!

Hi Elizabeth

Glad to help!

Please mark my reply as Helpful or Correct Answer - thanks

Neil