Drink Master 8000

D. Ryan RhodesPCB 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

PIC32MX µCtrl

RN-41Bluetoot

hDesktop/Laptop

w/ Bluetooth

Valve x18

I/OA

toD

Force x4

AtoD

RTD x4

AtoD

18

44

4

IR IN x 4

3.3V

UA

RT

2

LCD

2UA

RT

Thermoelectric Peltier

2RPGRPG

3

I/OI/O

12V

BuckConverte

r

Linear Regulato

r

3.3V

3.3VV

CC

GN

D

3.3V

VC

CG

ND

3.3V

3.3V

12V

3.3V

3.3V

IR IN x 4

3.3V

5V

Design Schematic

Micro

Solenoid Valves

BluetoothModule

PeltierControl

BuckConverter

LinearRegulatorWeight

Sensors

RTDSensors

IRRX/TX

LCD/RPG(need to

add)

RJ12

PCB Design: Microcontroller

DIP Switch

Considerations

• Large number of Ports used (location important)

• Decoupling/Bypass Caps

• Dip Switch for Debug/Reset/ETC

• Debug/In-circuit programming RJ12 jack

Figure 1.) PIC32MX Micro and Immediate peripherals

Pic32

RJ12Jack

Sensors

6

PCB Design: Power SupplyConsiderations:

• 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?

+12Von

Board

Fu

se

Bu

ck

Con

vert

er

Linear Regulat

or

Figure 2.) Power Supply

Key:

• GND(bottom)

• GND (top)

• 3.3V (bottom)

• 3.3V (top)

• 12V (bottom)

• 12V (top)

PCB Design: Power Rail Layout

12V Large trace (bottom)

Ground Rail (bottom)

3.3V Supply (bottom/top)

Figure 3.) Potential power supply rail layout

Questions/Comments?