Stopwatch, Counter & Morse Code Encoder

Background: Here are three main projects from my Embedded Systems class using the PIC16F833. They all took more than 10 hours per week each to make them work, but I learned a lot!

Counter

Specifications:

• Only use the PIC as the microcontroller.

• Count from 0 to 99.

• Overflows and underflows at 99 and 00 respectively.

• Code from scratch.

• Interrupt-based routine.

• Use time division multiplexing for controlling displays.

• Make the code easily modifiable for different wirings of 7-segment displays.

Results:

This was the circuit that we had:

Our code was structured as follows:

And a video of it working:

Stopwatch

Specifications:

• Counts from 0.0 seconds to up to 99 seconds.

• For the first 10 seconds, show 0.1 s increments.

• From the tenth second and beyond, show 1 s increments.

• Make it as accurate as possible when compared with a normal stopwatch.

• One pushbutton should be able to start/pause.

• A second pushbutton should be able to reset the timer.

• Use interrupts for the buttons.

• Use time divison multiplexing for controlling displays.

Results:

We used the same circuit as above:

Our software architecture for this one was as follows:

And this is a video of it working:

Morse Code Decoder

Specifications:

• Decode the duration of input waves as dashes or dots.

• Form symbols by detecting input waves using the diagram below between each pause.

• Minimum detectable length of an input is 100 μs.

• A dot is a high input with duration of 30 ms - 200 ms.

• A dash is a high input with duration 200 ms - 400 ms.

• A space is a low input with duration 30 ms - 400 ms.

• A pause is a low input with duration greater than 400 ms.

• The tolerance for the duration limits are of 50 μs.

• Not use __delay_ms calls in the code.

• Waiting state should have the display off.

• A symbol should be displayed for 2 seconds.

• If a character is not in the character set, show a dot in the display.

Results:

This is our circuit (deja vu):

This is our software architecture for this project:

And... this is a video of it working:

In the video, you can see it show "CE459" which is the part of ECE459 that I was able to capture in the video.

Unfortunately, I did not have a video documentation for another project in this class that involved writing BLE communication over a IEEE 802.15.4 protocol to communicate two nodes composed of mbeds and two Microchip MRF24J40MA radio. Our goal was to pass a message between these two nodes and get it back clearly. I learned many details about BLE and it was great to have more exposure to wireless communication.