A website for automating the grading process of embedded systems assignments with microcontrollers. Implements communication between the website and a microcontroller.
This system uses mBed's LPC1768 and NUCLEO F746ZG development boards. The student programs the NUCLEO board, while the LPC1768 records data from the NUCLEO and reports data back to the website.
Currently the only supported assignment. The student codes the NUCLEO board to interpret signals from the LPC1768 as binary numbers representing a period and duty cycle for a PWM wave and generates the waves. The LPC1768 records the time between rises and falls and sends the timestamps back to the website, which processes the data.
In order to communicate with the website, the LPC1768 must be set up as a USB device. See here for information on how to do that.
Communication between the two boards uses GPIO pins. The pin assignments for the boards can be found in their instruction files, located in the mbed_Board_Code directory, but a table has also been provided below. Check out the pin map for the NUCLEO and LPC1768 for the locations of these pins.
Period Pins, ordered from most significant to least significant bit
| LPC1768 | NUCLEO |
|---|---|
| p5 | PB_10 |
| p6 | PE_15 |
| p7 | PE_14 |
| p8 | PE_12 |
| p9 | PE_10 |
Duty Cycle Pins, ordered from most significant to least significant bit
| LPC1768 | NUCLEO |
|---|---|
| p11 | PE_7 |
| p12 | PE_8 |
| p13 | PG_9 |
| p14 | PG_14 |
| p15 | PF_15 |
| p16 | PE_13 |
| p17 | PF_14 |
Other Pins
| LPC1768 | NUCLEO |
|---|---|
| p21 | PE_0 |
| p25 | PC_10 |
| p27 | PC_8 |
The period is interpreted as (binary number + 1)*10 in ms (range of 10-320), while the duty cycle is the binary number as a percentage.
The library for communication between the board and the browser has been provided on the github page as the LPC1768_Library directory. Import it to the mBed online compiler when compiling the instructions for the LPC1768. This library is not needed for the NUCLEO board. The website uses the plotly.js library to graph the PWM waveforms, as well as Google Chrome's WebUSB API to communicate with the LPC1768. Google Chrome is the only supported browser for this reason.
Visit the website and use the select device button to connect the LPC1768. The send button allows you to send your own custom period and duty cycle to the LPC1768, while the Graph all test cases button uses 5 hard-coded test cases. Currently, the website does not save or store data.
WebUSB DFU by Devan Lai
empirikit-controller by larsgk
Autograder 1.0 by UCLA's NESL