Living/Undead Controller (LUC)
The LUC receives analog control inputs (throttle, steering, fire) as well as team select information. Upon successful connection with the selected team, the LUC acts as an R/C controller, sending the analog steering data to the HZV via a shared software protocol adopted by the entire class.
A 16-position digital encoder is used for team selection, along with visual feedback from a tri-color LED driven by a 3-channel, 4-bit software PWM module. Each channel of the LED circuit supplies <20mA of current which is well within the specifications of the LED and MOSFETs.
The keyswitch has three positions: OFF, ON, and TEAMSELECT. It controls power to the LUC and its TEAMSELECT position is used to connect to an HZV and begin control. The RC circuit attached to Q1, the main power control MOSFET, prevents loss of power during the moments when the keyswitch is turned from the ON position to the TEAMSELECT position and mechanical contact is briefly lost.
The throttle is comprised of a pair of force-sensitive resistors (FSRs) that are buffered by LM324 op amps before sampling by the on-board ADC of the PIC. One FSR for forwards and one for backwards. One axis (Y-axis) of the 3-axis accelerometer also outputs an analog voltage that is sampled by the ADC to determine steering direction. Additionally, the accelerometer's vertical axis (X axis) is sampled to inform the LUC when the bottle has been inverted ("taking a swig") so that the popper mechanism can be triggered.
Again, an Xbee module provides the RF link to the HZV.
A 16-position digital encoder is used for team selection, along with visual feedback from a tri-color LED driven by a 3-channel, 4-bit software PWM module. Each channel of the LED circuit supplies <20mA of current which is well within the specifications of the LED and MOSFETs.
The keyswitch has three positions: OFF, ON, and TEAMSELECT. It controls power to the LUC and its TEAMSELECT position is used to connect to an HZV and begin control. The RC circuit attached to Q1, the main power control MOSFET, prevents loss of power during the moments when the keyswitch is turned from the ON position to the TEAMSELECT position and mechanical contact is briefly lost.
The throttle is comprised of a pair of force-sensitive resistors (FSRs) that are buffered by LM324 op amps before sampling by the on-board ADC of the PIC. One FSR for forwards and one for backwards. One axis (Y-axis) of the 3-axis accelerometer also outputs an analog voltage that is sampled by the ADC to determine steering direction. Additionally, the accelerometer's vertical axis (X axis) is sampled to inform the LUC when the bottle has been inverted ("taking a swig") so that the popper mechanism can be triggered.
Again, an Xbee module provides the RF link to the HZV.
schematicluc.pdf | |
File Size: | 17 kb |
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LUC Power Calculation
The LUC was powered off of a 1000mAh Lithium Polymer battery.
Component current draw:
Zigbee: 45 mA peak TX, 50 mA peak Rx
PIC 'F690: Typical supply current is 2.8 mA at 20MHz
Accelerometer: Supply current of .400 mA
MOSFET driven LEDs: These low resistance MOSFETs are in line with 220Ohm resistors. I = 5V/ 220 Ohm = 20mA. There are 3 LEDs, but they will not all be on at the same time. We can assume that half are on continuously and the current drawn is 30 mA.
Force sensors: These are variable resistance force sensors, where the resistance decreases from 100kOhm as pressure is applied. We assume that 10 kOhm is in the force sensor, and it is in series with a 10k resistor. 5v/20kOhm = .25 mA
OpAmp: .7 mA supply current
Switch: In TEAMSELCT position, I = 5V / 1000Ohm = 5mA. We assume we are only in this position half the time, so 2.5 mA
Power Control path: (5V) / 10000Ohm = .5 mA
Encoder: 5V/10K = .5 mA - assume on average 2 switches will be connected, so total 1 mA
Total Current: 133.15 mA
1000mAh/ 135.15mA = 7.51 hours. We can run our LUC continuously on for at least 7.51 hours.
The LUC was powered off of a 1000mAh Lithium Polymer battery.
Component current draw:
Zigbee: 45 mA peak TX, 50 mA peak Rx
PIC 'F690: Typical supply current is 2.8 mA at 20MHz
Accelerometer: Supply current of .400 mA
MOSFET driven LEDs: These low resistance MOSFETs are in line with 220Ohm resistors. I = 5V/ 220 Ohm = 20mA. There are 3 LEDs, but they will not all be on at the same time. We can assume that half are on continuously and the current drawn is 30 mA.
Force sensors: These are variable resistance force sensors, where the resistance decreases from 100kOhm as pressure is applied. We assume that 10 kOhm is in the force sensor, and it is in series with a 10k resistor. 5v/20kOhm = .25 mA
OpAmp: .7 mA supply current
Switch: In TEAMSELCT position, I = 5V / 1000Ohm = 5mA. We assume we are only in this position half the time, so 2.5 mA
Power Control path: (5V) / 10000Ohm = .5 mA
Encoder: 5V/10K = .5 mA - assume on average 2 switches will be connected, so total 1 mA
Total Current: 133.15 mA
1000mAh/ 135.15mA = 7.51 hours. We can run our LUC continuously on for at least 7.51 hours.