After two weeks of working on the project, we realized that our project might be too complex to complete in the given time frame. In order to make the project more manageable, we proposed that the criminal database portion of the project be dropped. This was decide upon because the two main functionalities of the project, the fingerprint scanner and the SD card reader/sound production, have been taking a considerable amount of time thus far and still need large amounts of addition effort to complete. In addition, we could run into difficult down the road with transferring and comparing fingerprint files on the PIC as the details of this have not yet been worked out. Instead, we’d like to have the fingerprint scanner handle all fingerprint comparisons for the time being. This way, the focus of the project could be redirected to the two main elements. The terms of the project were renegotiated with the professor, and he accepted the exclusion of the criminal database.

I attempted to set up UART communication with the fingerprint scanner. This is being done with the aid of a pre-made code on GitHut in C++ for an Arduino. According to the fingerprint scanner datasheet, the scanner takes 12 bytes of data for every command packet, so twelve bytes are sent from the PIC to the fingerprint scanner per action. It has been verified on the scope that this data is being transmitted correctly. At the moment, the fingerprint scanner is having trouble receiving the data. The signal, for some reason, is being pulled down when the TX from the PIC is pulled into the RX of the fingerprint scanner. It was thought that the fingerprint scanner needed more power, but after supplying 5V to the power supply of the scanner instead of 3.3V, it was clear that this was not the case. Further troubling shooting will be completed in lab.

Plans for this coming week include getting the fingerprint scanner to communicate properly and creating methods to carry out the necessary communications between the PIC and fingerprint scanner.

This week, I focused on creating a TCP client using the TCP/IP stack that Microchip supplies in their MPLAB Harmony package. I have not yet been able to send data from the PIC32 client to a server on my personal laptop, but I’m nearly certain the problem just lies with the code and not how the hardware is connected. Unfortunately, my efforts will be redirected to the Fingerprint Scanner and Interface for the time being. I hope that we resolve the issue with the Fingerprint Scanner so that we could potentially re-implement the TCP client/server.
Over Thanksgiving, I will try to work on a control interface for our system. The interface will display components such as who has recently used the fingerprint scanner and at what time they used it. After break, I will work on the Fingerprint Scanner with Joe. I will initially help decode the C++ library that Joe started using for the Fingerprint Scanner.

A lot of time was spent working on the SD card and FAT32 interface. Both are now complete. A few weird bugs were discovered while working on reading the SD card, one of which took hours to resolve and still does not have a solution, but has been worked around. Once the SD card interface was deemed satisfactory, work was started on accessing the FAT file system of the SD card. Most of the libraries for FAT were very lengthy (at least 1000 lines) and were difficult to understand for someone who is fairly new to C. A fairly simple FAT16 library was used as a guideline for creating our own FAT32 accessing code. The code can interpret the boot sector, go to the root directory, then read data one sector at a time and follow cluster chains. WinHex, a memory viewing software, was very useful for verifying what data should be read at certain data locations.

The next step is to work on using DMA to output buffered data to the DAC in parallel to reading new data. Timing may be an issue because the data has to be read and formatted for the DAC before a DMA transfer finishes. Also a 12 bit DAC is being used for 16 bit data samples, so the sound quality will be decreased in downsizing. If the quality sounds poor, we may need to upgrade to a 16 bit DAC.

This week, my goal was to create a TCP server that could open a socket and listen on a specified port. It needs to be able to accept multiple types of data. The server will distinguish what the data is via op-codes sent by the client. Types of data the server must be able to receive: time of fingerprint, if the authentication was successful or not, and if yes, who’s fingerprint it is.

Status- Server is works fully, all operations work as intended. Mock client can connect to server, send multiple data types (and receive data too, if necessary), control certain functions of server, and disconnect from the server. Server side code implemented in Rust. I don’t believe there would be a problem have the server in Rust and the client in C/C++, but I’ll need to implement a client using Microchip’s PIC32 TCP stack in order to test.

Goals for next week- Implement the TCP client using Microchip’s TCP stack.

Week 1 mostly consisted of figuring out the steps needed to interface with an SD card from the PIC. Multiple sources were found that discussed and gave example code about SPI transfer and the inner workings of the file system on the card (FAT32). Initially a C++ library was going to be used for interfacing with the SD card peripheral, but this was dropped in favor of a simpler C library. The C library is currently being adapted to work with the PIC32 and the SDHC card being used. The SPI module was the first area looked at and was successfully modified to work with our devices. There was a troublesome reading issue with the PIC where the SD card would send a signal and the PIC would not accept it into the SPI receiver buffer. This was due to an overflow flag, which prevented new information from entering the buffer. The overflow register was reset before every read event in order to fix the error.

For this week, my goals were to make the schematic diagram for the system as well as to do research on how the fingerprint scanner will interface with the PIC. I’ve completed the schematic which is included below. This involved looking up how each device will communicate with the PIC and detailing what pins would be used for each device. It has been arranged so that the SD card reader and the Ethernet Module are on one SPI channel, and the LCD and the DAC are on the second SPI channel. The fingerprint scanner will communication via UART connection. In addition, I’ve found a library for the fingerprint scanner on Github.com which is in C++. I also soldered wires to the SD card reader so that it could be plugged into the breadboard and taught Phil how to solder while doing so. For next week, I will be working on converting this library to C and setting up the fingerprint scanner.