1. Txt Msg DJ PCB Layout Design Narrative
Team 22
John Doherty
The Text Message DJ allows party guests the opportunity to choose which songs they want to hear. Guests can text the name of the sing they want and the Text message DJ streams the song from the internet. Other features include a voting process, strobing lights, and blacklists
Everyone wants to dance to their favorite songs at a party, but rarely do guests have much say in song selections and playlists. The Text Message DJ aims to make song selection at a party a more democratic process. The Text Message DJ is a standalone unit that creates and maintains a party playlist based on song requests sent from party guests via SMS. Guests can send text messages containing song names and the Text Message DJ will automatically parse messages, sort requests, and play the most popular. In addition to playing the song audio, the Text Message DJ will strobe lights in sync with the beat of the currently playing song.

2. Block Diagram

3. PCB Considerations

4. PCB Considerations Overall Layout: GSM near side for antenna
Sockets and power source must plug into back
GSM near SIM to reduce potential to corrupt signal.
Critical signals near micro (Reset, JTAG)
Sensitive, fast switching digital logic signals separated
UART for GSM
UART for DMX
Equalizer signal
Separate digital com to micro do not cross
Separate units blocked off
All micro and gsm pins have headers

5. Micro Headers surround micro for easy access
Decoupling capacitors close to micro
Reset circuit close to micro
Easy to access JTAG pins

6. Power Supply Considerations
Three voltage requirements:
3.3V for micro and other digital logic
3.8V for GSM Module
5V for Raspberry Pi
GSM Module draws up to 2A:
This requires thicker traces
Must be careful to keep away form more sensitive signals
Add a ground pad to make wiring to ground easier
All components have decoupling capacitors close to component