ELECTRICAL DESIGN
Pinouts for C32 (Roamer)
Pinouts for E128 (POD)
Pinouts for PIC16F690 (ROAMER)
Motor Driver Circuit (ROAMER)
To drive the ROAMER motors (wheels for movement), we utilized 2 LMD18200, one for each wheel, with drive-coast PWM operation. The brake pin was held low and direction pins were toggled to control direction of movement.
Pod power consumption
E128:
Run supply current = 65 mA
Servo:
Typical current = 30 mA
Proximity Sensors (x2):
Average dissipation current = 15 mA
Accelerometer:
Normal operating current = 500 uA
XBEE:
Transmit current (typical) = 45 mA
Idle/Receive current (typical) = 50 mA
Button LEDs:
5V drop across 2N7000 and 220 ohm resistor
2N700 Rds(on) = 1.7 ohm (typical) for Vgs = 5V, Id = 50 mA
2.7 V typical voltage drop across LED
(5-2.7)V/221.7ohm = 10.2 mA
Total Power Consumption: A linear voltage regulator was used, so input voltage is multiplied by total current (excess voltage lost as heat). A 7.2 V, 1500 mAh battery was used.
Total Current = 65 + 30 + 15*2 + 0.5 + 50 + 10.2 = 185.7 mA
Total Power = 185.7 mA * 7.2V = 1.34 W
Required Battery Capacity = 185.7 mA* 8 hrs = 1486 mAh < 1500 mAh
Run supply current = 65 mA
Servo:
Typical current = 30 mA
Proximity Sensors (x2):
Average dissipation current = 15 mA
Accelerometer:
Normal operating current = 500 uA
XBEE:
Transmit current (typical) = 45 mA
Idle/Receive current (typical) = 50 mA
Button LEDs:
5V drop across 2N7000 and 220 ohm resistor
2N700 Rds(on) = 1.7 ohm (typical) for Vgs = 5V, Id = 50 mA
2.7 V typical voltage drop across LED
(5-2.7)V/221.7ohm = 10.2 mA
Total Power Consumption: A linear voltage regulator was used, so input voltage is multiplied by total current (excess voltage lost as heat). A 7.2 V, 1500 mAh battery was used.
Total Current = 65 + 30 + 15*2 + 0.5 + 50 + 10.2 = 185.7 mA
Total Power = 185.7 mA * 7.2V = 1.34 W
Required Battery Capacity = 185.7 mA* 8 hrs = 1486 mAh < 1500 mAh