Author: jpedraza

I spent this week looking at different approaches to interface between the modules and the Arduino.

Module Pins

As a team we decided that each module would get Vcc and Gnd, 3 pins to identify the module, and up to 2 data pins per module. Using the identification pins instead of unique data pins per module allows us to reduce the total number of pins used which is beneficial since the Pogo pins we’re using can be expensive. This also reduces the total number of single points of failure. Each module will therefore have a unique 3-bit identification code. They will be wired as shown, with Vcc and Gnd driving the ID pins:

 

Debouncing

I also considered the problem of debouncing. We don’t want a single button press to be registered as many presses in a short period of time. I compared software solutions with hardware solutions and landed on a few different approaches. For the button-press module, a simple RC filter with a Schmitt trigger should work:

 

The RC filter smoothes the transition from LOW to HIGH and the Schmitt trigger replaces the single threshold voltage with two separate LOW/HIGH threshold voltages. This ensures that any oscillations near threshold voltages do not result in an oscillating output.

Progress

My progress is slightly behind since we just recently settled on the schematics and electronic components so I haven’t made the initial module prototypes. To catch up, we will place the remaining component orders soon and work with what we’ve got for the simpler modules.

Deliverables for next week

Since our Arduinos have shipped, I hope to have some working code that interfaces with hardware components by next week. Ideally we’ll be able to see a physical button press register in Unity software. I also hope to place the orders for the remaining electronic components so we can build all of the remaining modules.

This week I researched ways to connect the modules to the panels and communicate between the modules and the Arduino.

Connecting modules to panel/controller

Players must be able to quickly connect and disconnect the modules without pausing gameplay and shifting their focus. This immediately rules out any connector that requires precise positioning, such as pin headers and sockets, USB connectors, audio jack style connectors, etc.

One viable option is a combination of pogo pins and magnets. Magnets will help guide the modules to the right position and the pogo pins can make a good connection without needing perfect alignment. They are also typically rated for tens of thousands of cycles (or more), which is important since the core of our game is switching modules around. These connectors are expensive, but worth it for us due to their importance.

Sending signals from the modules to the Arduino

I looked at a few different options for how modules can communicate with the pins of a microcontroller (e.g. Arduino). The simplest option would be a module that is just a button with passive electronic components.

 

I also looked at different debouncing techniques. For our MVP, a simple RC circuit might work but I also considered the possibility of incorporating a Schmitt trigger. We’ll make the decision later after more testing.

Progress and next week’s deliverables

My progress is on schedule. By next week I hope to have some working hardware that is ready to communicate with a microcontroller. It should provide reliable, noise-free signals based on user input. I will probably start with a simple module like the push-button, but will also work on more dynamic modules that involve more electronic components.