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Quadcopter Report
Information
Project Name: Quadcopter
Logo: NA
Group Member:
a. Sagar Patel.
Work: Schematic and PCB layout checking. PCB soldering. Fabrication.
b. Tonghua Li
Work: Schematic and PCB design. Firmware development. Report drafting.
Description
Quadcopter project is a summer PCB design class project. We are going to learn how to make
a PCBbased quadcopter from scratch. A 4.2V lithium battery that can supply 4A current is used
to power the quadcopter; including microcontroller power, mpu6050 sensor power and the
motors. STM32F4 microcontroller on this board runs at 168MHz, with its FPU(Float Point Unit)
module, it could easily process data from mpu6050 to get board orientation with complementary
filter. A RTOS named ChibiOS is running on STM32F4, it is compact, fast and well
documented; it is written in C, so many C libraries could be used, or ported. For wireless
communication, we used XBee module; this module only need simple setup with provided
software, and only 4 pins are enough for our purpose, it is communication protocol (UART) is
also made it easy to use.
Quadcopter includes the following main parts.
Quadcopter PCB board.
STM32F4 microcontroller. 4.2V LiBattery + case. 2 LDO power supply modules.
one for microcontroller, the other one for mpu6050. The reason to separate power supplyfor this two chips is to reduce mpu6050 power line noise, to get better data.
4 Motors 4 Motor blades XBee2 module wires or cable connectors that connects to the PCB circuit board to the motors. LED indicator.
Schematic Design
Overall
MCU
Power SupplyThis section is power supply for quadcopter. First LDO chip supply power for MCU andXBee, second LDO supply power for MPU6050. Two LDOs reduce power line noise forMPU6050. The last part of this section is battery connection circuit; 3 capacitors are usedto eliminate mcu power surge when motors are operating.
Motor Drive CircuitThis section is motor drive circuit for 4 motors. A diode is used for each motor is used to
prevent current backflow. Each MOSFET transistor coupled with a 10K pull downresistor, ensure the PWM signal quality.
Boot Mode ConfigurationBoot mode configuration is used for bootloader purpose. We left BOOT1 grounded, andonly control BOOT0, because here we either boot from Main Flash Memory or SystemMemory.
MPU6050MPU6050 use I2C communication protocol, 2 4.7K pull up resistors are used on I2Clines. Its AD0 pin is connected to ground to make its address is low address. Powersupply for this chip is VCCA, from isolated LDO.
Debug ConnectorSTM developed SW debug protocol, only two lines are needed for debugging. In order tosave space and weight, we give up JTAG.
XBee ModuleXBee use serial communication (UART) with MCU. Its TX pin is connected to RX pin onMCU, RX pin is connected to TX pin on MCU. But to make it safer, we add two 0 ohmresistors to TX, RX lines. So we can swap connection in case it is wrong.
Power Indicator LEDJust a indicator, but the resistor’s value is important to control lightness.
PCB Layout
1. OverallThe overall layout is based on module. Each module’s components are put together.This would help on hardware debugging, and reduce layout error rate.
2. Motor Drive CircuitSince four motors require 4A at the maximum, the power supply and ground tracesshould be as wide as possible. So we make a power supply plane for motors.
3. MPU6050This sensor is sensitive, motor driver circuit could produce a lot of noise, so we move itas far as possible away from the drive circuit. Also, its datasheet said it could not beplaced under XBee, and no traces are allowed to go through its bottom.
4. OscillatorIt is placed as close as possible to mcu, and no vias is prefered.
5. XBeeXBee’s antenna is oriented so it is far away from MPU6050 chip, to reduce interference.
Top Layer
Bottom Layer
Both Layers
Part Cost
Index
QTY Part Number Description CustomerReference
AvailableQuantity
UnitPrice
Extended Price
1 2 27723021ND CONN HEADER3POS 2.5MM
2Immediate
0.64 $1.28
2 50 A106051CTND RES 0.0 OHM1/10W JUMP 0603
50Immediate
0.003 $0.15
3 20 44517961ND CAP CER 0.1UF6.3V 10% X5R 0201
20Immediate
0.032 $0.64
4 10 44513001ND CAP CER 2200PF100V 10% X7R0603
10Immediate
0.048 $0.48
5 20 44551671ND CAP CER 2.2UF10V 20% X5R 0603
20Immediate
0.11 $2.20
6 10 44534241ND CAP CER 3300PF50V 10% X8R 0603
CAP060333nF
10Immediate
0.105 $1.05
7 25 A106050CTND RES 4.70K OHM1/10W 1% 0603
RES06034.7K
25Immediate
0.0052
$0.13
8 25 A103120CTND RES 680 OHM1/16W 0.1% 0603
RES0603680 25Immediate
0.2776
$6.94
9 2 4551611ND CONN HEADEREH TOP 2POS2.5MM
CONJST2EHBATT
2Immediate
0.13 $0.26
10 10 56834071ND DIODE SCHOTTKY40V 0.12ASOD123F
DIOSOD123F 10Immediate
0.214 $2.14
11 3 49768491ND IC REG LDO 3V0.3A SOT235
LDS3985M30R 3Immediate
0.75 $2.25
12 10 A30916ND CONN HEADERVERT 2POS .100TIN
M021X02Motor
10Immediate
0.315 $3.15
13 10 IRFML8244TRPBFCTND
MOSFET NCH 25V5.8A SOT23
NMOS_SOT233
10Immediate
0.213 $2.13
14 2 88714621ND CRYSTAL16.000MHZ 12PFSMD
OSC_4PIN 2Immediate
0.82 $1.64
15 2 49711767ND IC MCU 32BIT 1MBFLASH 64LQFP
STM32F405RG
2Immediate
11.45 $22.90
16 2 VLMS1300GS08CTND
LED SUPER RED0603 SMD
LED 2Immediate
0.45 $0.90
17 1 6021275ND XBEE PRO SET1MW PCBANTENNA
XBEEZB 1Immediate
17 $17.00
18 2 49329151ND CAP TANT 100UF6.3V 20% 1210
CAP1210100UF
2Immediate
1.49 $2.98
19 2 47838721ND CAP TANT 1UF35V 20% 1210
2Immediate
0.7 $1.40
20 2 47838871ND CAP TANT 4.7UF20V 10% 1210
CAP12104.7UF
2Immediate
0.49 $0.98
21 2 49329321ND CAP TANT 47UF10V 20% 1210
CAP121047UF
2Immediate
1.44 $2.88
Subtotal
$68.22
Shipping
Estimate
SalesTax
unknown
Total $68.22
PCB Control Board
PCB Quadcopter Board
Redesign
1. Connect one more pair of UART for debugging.
2. Remove swap resistors for XBee TX, and RX line. Since we know connection.
3. Separate components more to leave space for hand soldering.
Final Thoughts
Quadcopter is a nice project for learning PCB design. Including power, motor driving, signalprocessing. Design schematic and layout PCB require detail work, need to pay attentions todatasheet for each chip, it is easier than physical work (soldering) since PC software could pointout most of problems. Fabrication and soldering are challenges, a little careless would resultsolder touch each other and it is hard to notice. But all these are solvable once we have moreexperience on PCB design, like math problems, do more practise.
