PLAYER Schematics
COACH Schematics
The COACH side included a 'C32, a PIC16F690, and a XBee24 radio module. The 'C32 handled all of the COACH I/O, while the PIC communicated via UART with the XBee24 radio module. The 'C32 forwarded information to the PIC via SPI. The SPI network consisted of one master ('C32) and two slaves (the radio PIC and an output shift register that controlled the energy status and pairing LEDs).
We also used a 3-axis accelerometer module from Modern Device. We mounted it in the guitar such that the Z-axis was perpendicular to gravity and connected the X- and Y- accelerometer outputs to A/D pins. After calibrating on start-up, we were able to detect angular deviations from an equilibrium position and translated those angles into appropriate turning values that we then sent to our PLAYER. By using both the X and Y values of the accelerometer, we were able to make the angle detection more robust to calibration location and noise.
COACH Design Calculations
We decided to run our COACH off of a single 7.2V 1800 mAh NiCd battery. If we want to run untethered for 8 hours before recharging (as was called for in the project description), we need to limit our continuous current consumption to (1800 mAh / 8h) = 225 mA.
CURRENT SOURCES:
CURRENT SOURCES:
- XBee - 50 mA (peak, when transmitting)
- 74HC595 - <<1 mA
- ULN2003 - <1.25 mA
- Energy Store LEDs - 87.5 mA ( 7*(5V-2.5V)/200 )
- Pair LED - 20 mA ( (5V-3V)/100 )
- Team Color LED - 12.5 mA ( (5V-2.5V)/200 )
- Accelerometer - 0.4 mA
- Radio PIC - <1 mA
- 'C32 - 40 mA (continuous)
- LM7805 - <10 mA (8 mA quiescent current + ~0.5-1 mA under load)
- total current from all other devices (buttons, switches, etc.) averages out to less than 1 mA