Michael Davies

Andrew Mountain

Dan Hoang

Daniel Brink

Michael Davies

Andrew Mountain

Dan Hoang

Daniel Brink

Power Distribution Control Unit

Power Distribution Control Unit

Functionality

• Power Distribution Control Unit for Colorado Space Grant’s Satellite Citizen Explorer

• Implement commands from the satellite’s flight computer to provide the desired power to the unit’s subsystems

• Monitor specified temperatures and power buses

Schematic

• 17 – 4-Pin solid state relays

• Control using 5V logic

• Direct I/O with PIC

• Connected with desired voltage

Distribution of Power

Schematic

• Voltage Divider

• Maximum range voltage – low power consumption

• Analog multiplexer

• A/D converter on chip

Temperature

Schematic

Power Supplies

• Rigorously test power supplies

• Power draw on each bus

• Concern with noise on 5V power bus– Pi-Filter near each chip that require 5V

PCB Board

• 4-Layer Board

• 2 Parallel 7.15" X 7.65" boards

• Through hole parts for stability7.15" X 7.65"

Parts List• Microcontroller: PIC 16C77• Relays: DMO063• Clock: ACH-20.000MHz• Thermistor: YSI44901• 12v to 15v/-15v Converter: JR12D15-330• 12v to 24v Boost Converter: SI12S24-1250• 12v to 5v Converter: LANC1205W5S• Flight Computer Interface: RS485/422

Max3082ESH• PC Interface: Max208CN6

Microcontroller

Relays

ThermistorsTemperature Resistance Characteristic

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

-40 -20 0 20 40 60 80 100 120

Temperature [celcius]

Res

ista

nce

[o

hm

s]

Flight Computer InterfaceSerial Communication

PC Interface

Basic Software Functions

INITIALIZE

VOLTAGES

CURRENTS

TEMPS

DELAY

SEND INFO?

Basic Software FunctionsVOLTAGES

SET ANALOG SWITCH POS 1

A/D CONVERSION

SAVE VOLTAGE 1

SET ANALOG SWITCH POS 2

SAVE VOLTAGE 2

SET ANALOG SWITCH POS n

SAVE VOLTAGE n

RETURN

Basic Software Functions

INTERRUPT

RECEIVE TRANSMIT OTHER?

RETURN

Basic Software FunctionsRECEIVE

SET RELAYS SEND INFO

RETURN

READ BYTE

BOOT SEQUENCE

CD&H

1 min delay

ADCS

3-5 sec delay

Mnet

3-5 sec delay

Science

3-5 sec delay

Deploy

REQUIRED

-extra delay for FC

ARBITRARY

Basic Software Functions

Schedule

Division of Labor

• Michael Davies: Software

• Andrew Mountain: PCB/Schematic Design

• Daniel Brink: Hardware layout

• Dan Hoang: Hardware/Software interfacing

Milestones

• Milestone 1: Completed Prototype (wire wrap) and interface-able test code

• Milestone 2: Completed PCB Design and ready to order (first revision)

• Design Expo