Star Trek Communicator Badge

Horray! Now that the Teensy issues are solved I have been making super progress!

• The Accelerometer is working. I have it configured as a tap detector. I had to modify some libraries :( which will make code reuse a little pain, but it works!
• The microphone is working better than I expected. Actually, it is so sensitive, it is easy to overdrive it just by yelling while the badge is on your chest. Here's a screenshot of me humming a tone, while looking forward with the badge on my chest.

Hooray,

Thanks to some helpful guidance from Paul on the PRJC forum and I found a missing trace on one of the USB lines. I repaired it and am now talking with the Teensy. A huge step forward!

NOTE: the new version of the board does NOT have this mistake.

Next step, start talking with the accelerometer and microphone!

Hi Project followers! Do you have a good eye for soldering mistakes? I have posted detailed photos of the current board that is not working.

https://forum.pjrc.com/threads/41994-Custom-Teensy-LC-with-MK02-accepts-bootloader-but-no-USB?p=134651

If you spot a smoking gun I will forever be in gratitude!

Well, still no luck getting the current PCB up and running with the Teensy. I have decided to try making a new one.

• I improved the oscillator grounding
• I moved things around to make it a little easier to debug
• I have made the SMD pads to the teensy longer to make it easier to do hand touch-up soldering.

The main challenge I think is that I am trying to go straight from breadboarding to miniaturization. This makes it a bit harder to debug, not to mention solder. Right now I am not using a stencil which makes the solder paste application very tedious and error prone. Hopefully these improvements will make it a bit easier. You can find the new board on oshpark here:

Order Board Version 2.1 from Osh Park

I am having trouble getting my custom Teensy LC to boot up properly. The teensy is getting programmed by the bootloader chip and I see the crystal oscillator start running, but I am not getting any USB comms whatsoever. If anyone has any ideas, you can see more details and post a reply on the prjc forum here: https://forum.pjrc.com/threads/41994-Custom-Teensy-LC-with-MK02-accepts-bootloader-but-no-USB?p=132921

Before manufacturing a fully miniaturized system it is always wise to prototype at a larger scale first. This will help find bugs that will reduce the likelyhood of having to do a board respin later. In my case, must of the components I wanted to work with could easily be bought on Adafruit of Sparkfun with easily breadboardable headers.

In this breadboard prototype, I connected two Teensy LC micro-controllers to two wireless transceivers, microphones, speakers, etc. I wrote some code to configure one as a transmitter and one as a receiver to test the communications protocol/procedure, bitrates, and the system as a whole. Here are some of the lessons I learned:

1. The 3.3V regulator on the teensy is not powerful enough to power the receiver and speaker at the same time. I needed to have an external, higher-power regulator.
2. The Arduino library for the RF transceiver doesn't support the high-data-rate mode so it had to be modified for this application.
3. Any mic used needs high gain in order to be able to hear a human voice while attached to a lapel. Because a mic amplifier takes up valuable space and power I have found a mic that has an internal low-power amplifier. In addition, the teensy has an internal amplifier than can be used if additional gain is needed.
4. I thought the RF module had built features that made it simple to operate ( such as a power-on-reset feature) but it has been proven that it doesn't. Therefore, I have found that additional pins need to be connected to support all the modes I need.
5. Some times the Teensy doesn't play well with the RF library, therefore a manual reset button is a must and board space must be used.
6. The speaker amplifier consumes considerable power so it is necessary that I choose an amplifier that has a shutdown mode.