Fingerprint

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attilio
 
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Fingerprint

Post by attilio »

Hello,

when I power up the fingerprint sensor it just flash and then nothing happen

5 v + gnd power supply
pin 0 and 1 on arduino uno R3 (green on 0)
stable contact
empty sketc


software demo do not recognize the sensor

Question:

when the sensor is simply powered it should be lit (red) or not. ?

Thanks

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Franklin97355
 
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Re: Fingerprint

Post by Franklin97355 »

You should follow the tutorial first https://learn.adafruit.com/adafruit-opt ... r/overview it does not show connecting to pins 0 and 1.

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attilio
 
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Re: Fingerprint

Post by attilio »

Hi,

you are right but I red that to test the sensor with windows SW you have to
- connect the power supply
- connect pin 0 and 1 to use the arduino USB/serial adapter to communicate
-run an empty program on arduino
-start the demo sw
-search for a device

but again the question is
- to see the red led lit is it enough to power up the sensor or other init procedure and command must to be send to the sensor

Just to understand how it works !

Thanks for your help

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Franklin97355
 
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Re: Fingerprint

Post by Franklin97355 »

From what I've seen yes it should be red when powered. When did you purchase this? Are you connecting to a breadboard like in the demo or have you seperated the wires and are connecting directly to the Arduino?

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attilio
 
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Re: Fingerprint

Post by attilio »

franklin97355 wrote:From what I've seen yes it should be red when powered. When did you purchase this? Are you connecting to a breadboard like in the demo or have you seperated the wires and are connecting directly to the Arduino?
Hi Franklin,
after a few hours here you are my consideration (this is my first time with Arduino):
1- When you power up the sensor without any sw loaded it just blink (the sensor is working)
2-the sensor red light is on when you call getimage function
3-when you try to use the enroll sw there is a bad input routine (you have to press the id number, a char and send button, I rewrote the function
4- in the examples you have a function that return the number of image stored in the device. Here you have a bug on return value. Change in packet[3] will fix the problem
5-the arduino function Serial.available should return the number of the characters in the buffer to be read. normally the function work well but if you read 2 char string at very high speed the function sometime return 1 instead of 2. I fix this problem by adding a little delay of 100 ms after the function call to slow down the sw a bit. this seem to work well. I would check the library sw to try to understand why (but I have only the week-end to play.

Apart this the sensor work well.

Waiting for your opinion.

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adafruit_support_rick
 
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Re: Fingerprint

Post by adafruit_support_rick »

I'll check on the bugs you reported.

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attilio
 
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Re: Fingerprint

Post by attilio »

Hi Rick, have you found the bug or is my mistake?

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adafruit_support_rick
 
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Re: Fingerprint

Post by adafruit_support_rick »

attilio wrote:3-when you try to use the enroll sw there is a bad input routine (you have to press the id number, a char and send button, I rewrote the function
You mean this function?

Code: Select all

  while (true) {
    while (! Serial.available());
    char c = Serial.read();
    if (! isdigit(c)) break;
    id *= 10;
    id += c - '0';
  }
It will break on a newline, which is what you want. You may have your Serial Monitor configured to not send newlines automatically.
attilio wrote:4- in the examples you have a function that return the number of image stored in the device. Here you have a bug on return value. Change in packet[3] will fix the problem
I didn't see this one. Where is it, exactly?
attilio wrote:5-the arduino function Serial.available should return the number of the characters in the buffer to be read. normally the function work well but if you read 2 char string at very high speed the function sometime return 1 instead of 2. I fix this problem by adding a little delay of 100 ms after the function call to slow down the sw a bit. this seem to work well. I would check the library sw to try to understand why (but I have only the week-end to play.
This is normal behavior. You are simply seeing the result for calling available() before the second character has been received. At 9600 baud, it takes nearly 1ms to transmit a character, which is a very long time in microprocessor terms.

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