80 likes | 233 Views
Drink Master 8000. D. Ryan Rhodes PCB Design Considerations. Drink Master 8000. Creates a variety of water-based drinks from powders stored in the device. Two holding tanks for storage of multiple beverages. Device can self-clean, so solution cross contamination is eliminated. Block Diagram.
E N D
Drink Master 8000 • D. Ryan Rhodes • PCB Design Considerations
Drink Master 8000 • Creates a variety of water-based drinks from powders stored in the device. • Two holding tanks for storage of multiple beverages. • Device can self-clean, so solution cross contamination is eliminated.
Block Diagram 12V 3.3V Valve x18 18 3.3V I/O PIC32MX µCtrl LCD 3.3V 2 UART 3.3V 4 AtoD 3.3V Thermoelectric Peltier 2 I/O 4 IR IN x 4 Force x4 IR IN x 4 RTD x4 AtoD 3.3V RPG • RPG 3 I/O 4 AtoD 3.3V VCC 2 UART RN-41 Bluetooth GND 3.3V Desktop/Laptop w/ Bluetooth 12V 5V 3.3V VCC GND Buck Converter Linear Regulator
Design Schematic Buck Converter Solenoid Valves IR RX/TX Micro Peltier Control Bluetooth Module RJ12 LCD/RPG (need to add) Linear Regulator RTD Sensors Weight Sensors
PCB Design: Microcontroller • Considerations • Large number of Ports used (location important) • Decoupling/Bypass Caps • Dip Switch for Debug/Reset/ETC • Debug/In-circuit programming RJ12 jack Pic32 DIP Switch RJ12 Jack Sensors Figure 1.) PIC32MX Micro and Immediate peripherals
PCB Design: Power Supply • Considerations: • Need a large 12V supply and ground rail for Solenoid and Peltier • Have a 12V Trace (250-300 mil?) on bottom of board at “north” edge? • Large Ground Plane (200 mil?) across middle of most of the board? • Expecting 16 valves * 0.5 A * 12 V + 2 valves * 1.5 A * 12V = 132 W on top edge 12V rail • Expecting 6A * 12V = 72 W for Peltier supply • Need to minimize EMI for FCC/reliability reasons. Use multiple small parallel ground “rails” that connect to a single main ground? • See next slide for example • Need to supply 3.3V to the other side of the board. How is it best achieved? Power rail on bottom board with vias near central points? +12V on Board Buck Converter Fuse Linear Regulator Figure 2.) Power Supply
PCB Design: Power Rail Layout • Key: • GND(bottom) • GND (top) • 3.3V (bottom) • 3.3V (top) • 12V (bottom) • 12V (top) 12V Large trace (bottom) Ground Rail (bottom) 3.3V Supply (bottom/top) Figure 3.) Potential power supply rail layout