QR Barcode readers with PIC16f877A (Updated)

Hey all ,
I hope you are doing well and staying safe during this pandemic,

I have posted before that I'm working on a Door Lock system project with RFID module and key pad using Pic16f877a and I want to add QR to my project .
after a saw the answers I did not know actually what to do for that I started to search on internet about how could add QR reading future to my project and i finally got those choses

1.using ESP-32 CAM
-issue : how can I store many of QR codes on it ?

2.Using a QR reader with UART
-issue : but I have already used my UART ports to interface the RFID module is their any way to use the UART ports for 2 modules ?
and in this way how I can store my QR codes ? can I use external memory ?

3. using Zbar library with any Webcam
-issue : I found this open-source library but I do not know how can I use it with my project which is a library to read the QR code with normal web cam
I liked this library and I want to use it may you please guide me about how I can use this library with Pic16f877a or with any another MCU and also how can I store the QR codes in the project .

I attached my circuit diagram which shows the connections with my microcontroller to show you which ports I used and which ports are free.

I write my code on MicroC.


I'm looking forward for your advice

Thanks,

The 877 is not really big enough to do what you want but can do it. I think you need a hardware solution. I'd go with the QR reader using a software UART on D6 & D7. To store your codes, use an I²C memory (24C1024 is 131k) on RC3 (SDA) and RC4 (SCL) - move your LEDs to port A. An alternative method is to have the QR code contain a 64 bit number along with other stuff, check the other stuff is correct and then check the 64 bit number against your database - only 8 locations per record required.

Mike.

I would suggest this as a better way to connect your components:

I would also connect the R/W line of the LCD as this greatly speeds up the LCD routines. I'm not sure that sharing of I/O lines is needed with so many unused pins. Plus, if an I²C memory is decided upon then RC3 & 4 are required for hardware I²C.

Mike.

Pommie said:

The 877 is not really big enough to do what you want but can do it. I think you need a hardware solution. I'd go with the QR reader using a software UART on D6 & D7. To store your codes, use an I²C memory (24C1024 is 131k) on RC3 (SDA) and RC4 (SCL) - move your LEDs to port A. An alternative method is to have the QR code contain a 64 bit number along with other stuff, check the other stuff is correct and then check the 64 bit number against your database - only 8 locations per record required.

Mike.

Click to expand...

Thank you for your hrlpfull answer,
I started to learn how to read and write on I²C memory as you said but I actually using RFID with The TX RX UART ports but you said that I can connect any QR reader with D6 and D7 , it's possible to send data via D ports ?
If possible which is the cheapest QR reader with UART outputs would you recommended to me ?

Respectfully,
Abdo.

Dan Soze said:

I would suggest this as a better way to connect your components:

View attachment 131246

Click to expand...

Thank you for your effort ,
Does D4,D5,D6 and D7 LCD inputs are connecting with the keypad A, B,C and D inputs ? If that , is it will work core ttly without any problems ?
Abdo.

Pommie said:

I would also connect the R/W line of the LCD as this greatly speeds up the LCD routines. I'm not sure that sharing of I/O lines is needed with so many unused pins. Plus, if an I²C memory is decided upon then RC3 & 4 are required for hardware I²C.

Mike.

Click to expand...

Thank you again I appreciate your effort ot thinking to help me
But I did not understand what you said here
May you explain more clearly (),
Abdo

You have the R/W line of the LCD connected to ground so can't read from the LCD. The LCD has a busy flag that you can read to check if the LCD is ready to accept the next command/data.

Mike.