Control Feasibility

• ATMega328 has 18 I/Os (16 brought out)• 5V Operation @ 16MHz External OSC• 4 out of 6 Successive A-to-D ports available• Features SPI,6 PWM ports,I2C and UART• Large community support and freely available

libraries

Servo Feasibility

• Pulse Width Modulation Control– Pulse width determines angle of servo.

• Current Measurements:• 700 mA transients• 500 mA under stable load• 40 mA holding idle• 5 mA idle

Servo Feasibility Cont.

• Assuming 7.2V 5AH Battery– 5V servo voltage rail

(switching buck)– Discharging at 0.1068C

(worst case) would take 46.8164 hours to fully discharge

Calculations

5V*(.700A*1.1) = 3.85W(Including 10% loss by Buck)

3.85W = 7.2V * IBatt

IBatt = 0.5347 A

0.5347A/5AH = 0.1068 C MAX

5AH/0.1068C = 46.8164 hours to full discharge

Protection

• Mainboard uses two separate PTCs– Buck protection 3A Trip Current– Control protection 0.1A Trip Current

• Buck circuit also includes over current, under voltage, and thermal protection (built into the IC)

Mainboard Layout - Bottom

Mainboard Layout – Top

PCB Schematic

PCB Schematic Continued

Chassis IO Board

• Brings out 10 usable IOs to the outside of the LVE

• 4 Have Analog In Capabilities• 4 Have PWM Capabilities• 6 Are General I/O• IO Pins Protected By Custom Shroud

Chassis IO Layout

Chassis IO Layout

Chassis IO Custom Shroud