Can't template file compare with SEN0188

[DNTM2802]

I want to store a fingerprint template in a file, and then compare it with one newly obtained with the sensor. For that I'm using the code in the example you provided (examples/fingerprint_tempalte_file_compare.py).

Im getting the following error:

Traceback (most recent call last):
  File "/home/pi/biometrics/tests/fingerprint_compare_files.py", line 200, in <module>
    fingerprint_check_file()
  File "/home/pi/biometrics/tests/fingerprint_compare_files.py", line 72, in fingerprint_check_file
    i = finger.compare_templates()
  File "/usr/local/lib/python3.9/dist-packages/adafruit_fingerprint.py", line 324, in compare_templates
    self.confidence = struct.unpack(">H", bytes(r[1:3]))
struct.error: unpack requires a buffer of 2 bytes

Which is relted to this function:

def compare_templates(self) -> int:
    self._send_packet([_COMPARE])
    r = self._get_packet(14)
    self.confidence = struct.unpack(">H", bytes(r[1:3]))
    self._print_debug("compare_templates confidence:", self.confidence)
    return r[0]

The value of r after r = self._get_packet(14) is [1], which is the code for PACKETRECIEVEERR.
So what is happening? The sensor is unable to make the comparison? The problem is the _COMPARE instruction or it may be the data that was sended before?
Note that everything works for the flash memory option (examples/fingerprint_simpletest_rpi.py).

Thank you.

[decentralMind]

Hi, I'm facing similar issue with R307 fingerprint sensor. Did you solved the problem?

[ajiekurniawansaputra]

Hi guys, I have solved the problem, it's in the _send_data function, the checksum should concatenate ENDDATAPACKET on the last send. I have request pull on the main branch, I hope they accept my request.