Pattye Brown

ZigBee and Low-Cost Wireless Networks For sensing and control applications ®

Many sensing, monitoring and control applications offer a

Figure 1: Example, stand alone transceiver for use with various microcontrollers (Freescale Semiconductor MC1320X)

unique potential to incorporate low-cost wireless networking functionality. Low-cost wireless networking solutions often require ranges of 30-70 meters or less, data rates of 250 kbps or less and, in many cases, the capability to achieve optimum battery life, particularly for end node functions. The wireless

MC1320x

networking implementation can be enhanced with proactive analysis of several key factors prior to design start. A matrix of

Tx/Rx Switch

Digital Transceiver

Analog Receiver

Frequency Generator

Analog Transmitter

these key factors will help you choose your components and

RF IC Timers

solutions. Reference design schematics are also provided as a baseline for design initiation. Consider reviewing the following

Digital Control Logic

RAM Arbiter

Power Management

Voltage Regulators

Figure 2: Example, integrated system in package (SiP), transceiver and microcontroller (Freescale Semiconductor MC1321X)

Packaging

MC1321x HCS08 CPU

Frequency Generator

Digital Transceiver

Analog Receiver

Tx/Rx Switch

• Integration • Wireless networking topologies (Figure 3) Radio (RF modem or transceiver) Performance Operating voltage Data rates Range Channel flexibility Output power Sensitivity Power management Peripherals Clocking Multi-tier software Ease of hardware and software design Antenna design

Buffer RAM IRQ Arbiter

areas when determining your design requirements:

Analog Transmitter

RF IC Timers

Flash Memory

Background Debug Module 8-ch., 10-bit ADC 2 x SCI

Digital Control Logic

Buffer RAM

RAM

I2C

Low Voltage Interrupt

16-bit Timers

IRQ Arbiter

RAM Arbiter

Keyboard Interrupt

COP

Power Management

Voltage Regulators

Internal Clock Generator

Up to 39 GPIO

• Microcontroller (MCU) CPU features Performance Memory options Power management Clock source options Analog to digital conversion Peripherals Packaging In-circuit debug and programming Ease of software and hardware design Such analysis will provide an organized perspective for engineering decisions, an avenue toward design success, a fast time to market, and an easier implementation of the low-cost wireless networking.

ZigBee and Low-Cost Wireless Networks 41

A variety of implementation alternatives for low-cost wireless

ZigBee, an IEEE® 802.15.4 standards-based solution, as

networking can give you a high level of flexibility in the design

defined by the ZigBee Alliance, was developed specifically

process. As one alternative, consider solutions from providers

to support sensing, monitoring and control applications. The

that offer various configurations of stand-alone transceivers

ZigBee solution offers significant benefits, such as low power,

to be used in conjunction with a wide selection of MCUs

robust communication and a self-healing mesh network. The

(Figure 1). As a second and equally effective alternative,

ZigBee solution frequencies are typically in the 868/915 MHz or

consider the newest solutions which offer integrated

2.4 GHz spectrums.

transceiver/MCU products (Figure 2). Reuse of design

The ZigBee data rate for technology solutions is 250 Kbps.

components and engineering investment may be important

Power consumption must be extremely low to allow battery

as you work on multiple, yet similar, end products. Therefore,

life that is measure in years (equivalent to the shelf life of the

a structured evaluation of solution options can be both cost

battery) using alkaline or lithium cells. ZigBee technology

and resource efficient. Well thought out research may provide

theoretically supports up to 65,000 nodes. Common

a basis for several end products to be designed from a single

applications in sensing, monitoring and control, which are

foundation.

best supported by a ZigBee technology solution include: • Personal and medical monitoring

Wireless Networking Technologies

• Security, access control and safety monitoring

The 2.4 GHz industrial, scientific and medical (ISM) band

• Process sensing and control

supports multiple short range wireless networking technologies.

• Heating, ventilation and air conditioning (HVAC)

Each alternative has been developed to optimally serve specific applications or functions. The networking topologies most

sensing and control • Home, building and industrial automation

commonly associated with the 2.4 GHz frequency range are

• Asset management, status and tracking

Bluetooth™, WiFi™ and ZigBee® as well as other proprietary solutions. Non-standards-based proprietary solutions offer some

• Fitness monitoring

risk as they are vendor dependent and thus subject to change.

• Energy management

Figure 3: Wireless Networking Technologies ZigBee®

Bluetooth®

UWB™

Wi-Fi™

LonWorks®

Proprietary

EIA 709.1, 2, 3

Proprietary

N/A

Standard

IEEE® 802.15.4

IEEE 802.15.1

IEEE 802.15.3a (to be ratified)

IEEE 802.11 a, b, g (n, to be ratified)

Industry Organizations

ZigBee Alliance

Bluetooth SIG

UWB Forum and WiMedia™ Alliance

WiFe Alliance

LonMark Interoperability Association

Star

Star

Star

Mediumdependent

P2P, Star, Mesh

868/915 MHz 2.5 GHz

2.4 GHz

3.1–10.6 GHz (U.S.)

2.4 GHz 5.8 GHz

N/A (wired technology)

433/868/900 MHz 2.4 GHz

Data Rate

250 Kbps

723 Kbps

110 Mbps–1.6 Gbps

10–105 Mbps

15 Kbps– 10 Mbps

10–250 Kbps

Range

10–300m

10m

4–20m

10–100m

Mediumdependent

10–70m

Power

Very low

Low

Low

High

Wired

Very Low–Low

Alkaline (Months–Years)

Rechargeable (Hours–Days)

Rechargeable (Hours)

N/A

Alkaline (Months–Years)

65,000

8

128

32

32,000

Topology Mesh, Star, Tree RF Frequency

Battery Operation (Life) Nodes

42 freescale.com/beyondbits

100–1,000

RF Modem or Transceiver (Radio) Several radio frequency (RF) modem features should be

full-function/coordinator or end node devices, often to the full shelf life of the battery.

considered for implementing low-cost wireless networking

Look for additional essential peripherals, such as internal timer

systems. Most low-cost personal area network (PAN) RF

comparators, which are available to reduce MCU resource

modem solutions recommend power supplies from

requirements. General purpose input/output ports (GPIO) are

2.0–3.6V.

available in various different configurations and counts. GPIO is

For lightweight wireless networks, low data rates are adequate to support monitoring, sensing and control functions and also help manage system power consumption. 250 kbps offset quadrature phase-shift keying (O-QPSK) data in 2 MHz channels with 5 MHz spacing between channels with full spread-spectrum encode and decode is most often selected for these application types. In these environments, the transceiver wakes up, listens for an open channel and transmits small packets of data at lower data rates. Then it shuts down until the next event is indicated. The sequencing, fast power on latency, lower data rates and small data packets allow an 802.15.4 transceiver to select time increments where the data transmission will be most effective. As mentioned previously, for sensing and control subsystems, data transmission range and power requirements are best supported with ZigBee technology solutions. The typical range defined by the ZigBee Alliance specification is 10–70m, however, many solutions offer line-of-sight ranges well beyond this. It is important to review the number and types of transceiver channels available in relation to the planned design. Selectable transceiver channels offer the designer the option to take advantage of channels which minimize noise, particularly staying away from the more crowded 2.4GHz WiFi channels. You should look for typical transmit output power in the 0 dBm up to +4 dBm range. Receive sensitivity typically in the -90 dBm range will offer adequate capabilities for sensing, monitoring and control functions. Buffered transmit and receive data packets simplify management of low-cost microcontrollers that will be used with the transceiver. The radio or transceiver should also offer link quality and energy detect functions for network performance evaluation. Multiple power-down modes offer power saving features to minimize system power consumption. These typically include off current, hibernate current and doze currents in the single digit microamp (µA) ranges. Programmable output power also allows the designer to reduce power consumption where range or environment require less power to achieve transmit and receive objectives. Ensuring these functions are offered in the selected solution will aid in maximizing battery life in battery operated

heavily dependent on interface requirements with other devices within the application. In solutions which offer the flexibility of a transceiver with separate MCU, the communications is handled through the serial peripheral interface (SPI) port. As would be expected, when the radio and MCU are integrated into a single package or chip, the transceiver communicates to the MCU through the onboard or internal SPI command channel. Also, integrated solutions which include low noise amplifiers (LNA), power amplifiers (PA) with internal voltage controlled oscillator (VCO), integrated transmit/receive switch, on-board power supply regulation and full spread-spectrum encoding and decoding reduce the need for external components in the system and lower overall system cost. A wide array of system clock configurations gives you flexibility in end system design. Options which allow either an external clock source or crystal oscillator for CPU timing are most suitable. A 16 MHz external crystal is typically required for the modem clocking. The ability to trim the modem crystal oscillator frequency helps to maintain the tight standards required by the IEEE® 802.15.4 specification. Depending on the complexity and requirements of the end design, you are best served by vendors who offer multiple network software topology alternatives. These may include a simple media access controller (MAC) configuration which utilizes MCU flash memory sizes from 4 KB and up and supports point-to-point or simple star networks. Fully 802.15.4 compliant MAC and full ZigBee compatible topologies, while requiring more memory, provide the added support of mesh and cluster tree networks. Ease the design process by using vendor provided reference designs, hardware development tools and software development tools. For hardware development tools, simple getting started guides, essential boards with incorporated LED and LCD for a visual monitor plus cables and batteries provide an easy out-of-the-box experience. These tools help you set up a network within minutes and actually evaluate network and solution performance. In the past some software design tools, specifically those which support fully ZigBee compliant networks, have been extremely difficult to use. To reduce the complexity of RF modem preparation, look for vendors that offer graphical users interface (GUI)-based software design tools that walk the designer through a step-by-step transceiver set-up.

ZigBee and Low-Cost Wireless Networks 43

3V0

C117 1µF

9 10 11 12 13 14 15 16

1 2 3 4 5 6 7 8

EP

N/C XOUT YOUT N/C ST N/C N/C N/C

17

ST VSS VDD STATUS VOUT VSS VSS VSS

Z Axis ACC

MMA1260D

N/C N/C N/C N/C N/C N/C N/C N/C

IC106

X-Y Axis ACC

8 7 6 5 4 3 2 1

5V0

1.0K

R102 220R

3V0

R109

R101 220R

D101 Green_LED LED1

1.0K

R112

1.0K R114 1.0K Not Mounted

D102 Green_LED LED2

C119 100nF

3V0

Tx CTS Rx RTS

'9p Female Ang'

C123 1µF Not Mounted

R103 220R

R104 220R

R108

D103 Green_LED LED3

3V0

1 6 2 7 3 8 4 9 5

D104 Green_LED LED4

16 15 14 13 12 11 10 9

MMA6261Q

N/C N/C VDD VSS N/C N/C N/C N/C

IC104

3V0

J102

C124 100nF

C120 100nF

11

17 16 9 8

18

7

3

1

20 14

19

R113 1.5K

R116 1.0K Not Mounted

Switch_SPST_SMD

Switch_SPST_SMD

Switch_SPST_SMD

SW4

S104

SW3

S103

SW2

S102

SW1

S101

2 4 6 8 10 12 14 16 18 20 22 24 26

MAX3318E

INVALID

T1OUT R1IN R2IN T2OUT

GND

V-

V+

READY

FORCEOFF FORCEON

VCC

IC103

Switch_SPST_SMD

C109 100nF C110 100nF

V_RS232

Figure 4: 13192 SARD Reference Block Diagram

m2

m1

2*13p

J105

1 3 5 7 9 11 13 15 17 19 21 23 25

T1IN R1OUT R2OUT T2IN

C2-

C1C2+

C1+

13 15 10 12

6

4 5

2

PTA6 PTA7 PTC0 PTC1 PTC5 PTC6 PTG1

C112 100nF

C111 100nF

3V0

C101 100nF

GPIO1 GPIO2

PTA6 PTA7

16 41

17 40

22 23 24 25 26 27 28 29

18 19 20 21

32 33 34 35 36 37 38 39

MC9S08GT60

VSS VSSAD

VDD VDDAD

PTB0/AD0 PTB1/AD1 PTB2/AD2 PTB3/AD3 PTB4/AD4 PTB5/AD5 PTB6/AD6 PTB7/AD7

PTD0/TPM1CH0 PTD1/TPM1CH1 PTD3/TPM2CH0 PTD4/TPM2CH1

PTA0/KBIP0 PTA1/KBIP1 PTA2/KBIP2 PTA3/KBIP3 PTA4/KBIP4 PTA5/KBIP5 PTA6/KBIP6 PTA7/KBIP7

IC102

J106

3 1

VREFH VREFL

RESET

PTG2/EXTAL PTG1/XTAL PTG0/BKGD/MS

PTC0/TxD2 PTC1/RxD2 PTC2/SDA PTC3/SCL PTC4 PTC5 PTC6

IRQ

30 31

1

44 43 42

3V0

C102 100nF

PTG1

PTC5 PTC6

C130 100pF

6 4 2

Switch_SPST_SMD

RESET Switch

SW5

S106

BDM PORT

5 3 1

470K

C103 100nF

100nF

32 29 28 21 30

31 22

15

14 13 12

20

19 18 17 16

11 10 9 8 23 24 25

C104 100nF 33

3V0

S105 Switch

C129

3V0

GPIO1 GPIO2 TP102 TP103

R105

VDDA

TP101

GPIO1 GPOI2

Jumper_2x3

J101

CLKO

ATTNB RXTXEN RSTB

2 3 4 5 6 7 8

SS MISO MOSI SPICLK IRQ

PTC0 PTC1

1

9V Holder and Connector - Female

3

J108

+

11

9 10 12 13 14 15

3V0

9V battery

2

J107

2 9V Holder and Connector - Male

PTE0/TxD1 PTE1/RxD1 PTE2/SS PTE3/MISO PTE4/MOSI PTE5/SPSCK

1 3 2

1 2 3

DC

VIN

MC13192

GND

VDDA VDDLO1 VDDLO2 VDDD VDDVCO

VBATT VDDINT

CLKOo

ATTNBi RXTXENi RSTBi

IRQBo

CEBi MISOo MOSIi SPICLKi

GPIO1 GPIO2 GPIO3 GPIO4 GPIO5 GPIO6 GPIO7

TINJ_P

RIN_P

RIN_M

1

XTAL2

XTAL1

SM

PAO_M

PAO_P

TINJ_M

VOUT

27

26

7

6

5

4

3

2

1

IC109 5V0 LP38690DTX-5.0

IC101

C113 1µF

3 GND 2

3 VIN

C108 220pF

16.000MHz

C105 6.8pF

C106 6.8pF

L101 6.8nH

+

1

C131 0.5pF

2

C132 10µF

1

C127 18pF

C126 18pF

500mA

R117

MBR0520LT1

D106

C107 220pF

W103 EL=58 deg, Z=120ohm 11.5mm

W102 EL=22.5 deg, Z=120ohm 4.5mm

Jumper_1x2

J103 1 2

W101 EL=22.5 deg, Z=120ohm 4.5mm

-

2-3V battery

VOUT

IC108 LP38690DTX-3.3

R106 220R Not Mounted

X101

C116 10µF

TP104

GND 2

44 freescale.com/beyondbits ANT101

ANT102

W104 EL=58 deg, Z=120ohm 11.5mm

C128 0.5pF

R118 220R

D105 Green_LED LED5

3V0

C114 4.7µF

10R

R107

C115 4.7µF

V_RS232

5 6

1 2 3 4

VCC

1 3 5 7

1 3 5 7

1 3 5 7

PTB0/AD0 PTB2/AD2 PTB4/AD4 PTB6/AD6

PTC0/TxD2 PTC2/SDA PTC4 PTC6

PTD2 PTD5 PTD7

PTA0/KBD0 1 PTA2/KBD2 3 PTA4/KBD4 5 PTA6/KBD6 7

Not Mounted

PTA1/KBD1 PTA3/KBD3 PTA5/KBD5 PTA7/KBD7

2 4 6 8

PTB1/AD1 PTB3/AD3 PTB5/AD5 PTB7/AD7

2 4 6 8

PTC1/RxD2 PTC3/SCL PTC5 PTC7

2 4 6 8

PTD4 PTD6 PTG1/XTAL

Not Mounted Not Mounted

Port D/G

Jumper_2x4

J110

Not Mounted Not Mounted

Port C

Jumper_2x4

J109

Not Mounted Not Mounted

Port B

Jumper_2x4

J108

Not Mounted Not Mounted

Port A

Jumper_2x4

2 4 6 8

Not Mounted

RS101 500mA 1 2

J107

DATADATA+

'USB Serie-B Right Ang.'

SHIELD SHIELD

VUSB DATADATA+ GROUND

J102

R133 0R

Tx CTS Rx RTS

VOUT

C129 100nF Not Mounted

8 7 3 4

VCC

R121

CS SCK SO SI

1 6 2 5

7

6

5 4

8

3 29

VCC

Q100 MMBT3904TT1 Not Mounted

KMI-1240 Not Mounted

PZ100 +

Not Mounted

AT25HP512C110CU-2.7

VCC HOLD WP GND

IC104

R138 10K Not Mounted

INVALID

T1OUT R1IN R2IN T2OUT

GND

V-

V+

READY

FORCEOFF FORCEON

VCC

R134 0R Not Mounted

Not Mounted

1

RST

T1IN R1OUT R2OUT T2IN

C2-

C1C2+

C1+

10 13 14 15 16 17 18 19 20 21 22

23 24 25 26 27 28 1 2

12 11

9

13 15 10 12

6

4 5

2

VCC

LED4

D104 Red_LED

VCC

D103 Red_LED

LED3

0R 0R

R115 R117

D102 Red_LED

LED2

D101 Red_LED

D110 BAV99 Not Mounted

2

V_BB 1

TP107

V_BB

0R

R113

R104 R103 R102 R101 220R 220R 220R 220R Not Mounted Not Mounted Not Mounted Not Mounted

Not Mounted TP130

LED1

VCC

0R

R118

VCC

0R

R116

Not Mounted Not Mounted Not Mounted TP127 TP128 TP129

VCC

RESET Switch

SW5

S105 DTSM-644

BDM PORT

Jumper_2x3

5 3 1

J101

1.0K Not Mounted

R125

R140 0R Not Mounted

C115 100nF

C114 100nF

R119 4.7K Not Mounted

6 4 2

VCC

R139 0R Not Mounted

NC NC NC NC NC NC NC NC NC NC NC

CTS RTS RXD TXD DSR DTR DCD RI

SUSPEND SUSPEND

CP2102

DD+

VBUS

GND GND

VDD

REGIN

IC103

MAX3318E

C131 100nF Not Mounted

27R Not Mounted 27R Not Mounted

R120

R122 0R Not Mounted

11

17 16 9 8

18

7

3

1

20 14

19

IC102

C117 1µF Not Mounted

V_USB

C112 100nF

C116 100nF Not Mounted

C113 100nF

V_UART

J104 Jumper_1x4

C110 100nF

TP106

TP105

R105 220R

C108 100nF

R114

C109 100nF

V_BB

0R

100nF Not Mounted

C111

PTG1/XTAL

PTD4 PTD5 PTD6 PTD7

PTD2

12 13 14 15 16 17 18 19

62 63 64 1 2 3 4 5

72

45 6

60 61

7 8 9 10 11

70 47 71 48 49 50 51

R143 4.7K Not Mounted

V_BB

PTC0/TxD2 PTC1/RxD2 PTC2/SDA PTC3/SCL PTC4 PTC5 PTC6 PTC7

PTA0/KBD0 PTA1/KBD1 PTA2/KBD2 PTA3/KBD3 PTA4/KBD4 PTA5/KBD5 PTA6/KBD6 PTA7/KBD7

R106 470K Not Mounted

V_BB

V_BB

0R

TP121

LED5

D105 Green_LED

R107

VCC

SW4 Not Mounted

S104 DTSM-644

Not Mounted

SW3

S103 DTSM-644

Not Mounted

SW2

S102 DTSM-644

Not Mounted

SW1

S101 DTSM-644

1 2 3 4

R137 0R Not Mounted

IC101 MSQA6V1W5T2

Not Mounted

Not Mounted

5

C

S100-4 MFP461N-RA

m2

m1

J103 '9p Female Ang'

4

10 11 12

1 6 2 7 3 8 4 9 5

3

C

Vs+ Vo GND

MC13213

Exposed Pad

VDD VDDAD

VREFH VREFL

PTG0/BKGD/MS PTG1/XTAL PTG2/EXTAL CLKOo RESET

PTD1/RXTXENi PTD2 PTD3/RSTBi PTD4 PTD5 PTD6 PTD7

PTC0/TxD2 PTC1/RxD2 PTC2/SDA PTC3/SCL PTC4 PTC5 PTC6 PTC7

PTA0/KBD0 PTA1/KBD1 PTA2/KBD2 PTA3/KBD3 PTA4/KBD4 PTA5/KBD5 PTA6/KBD6 PTA7/KBD7

IC100

Not Mounted

IC109 LM61BI

Not Mounted

R123 0R

J105 DC

VDDA VDDLO1 VDDLO2 VDDD VDDVCO

VBATT VDDINT

XTAL2

XTAL1

PAO_M PAO_P TINJ_M RFIN_P RFIN_M CT_Bias SM

ATNBi IRQ/IRQo

GPIO1 GPIO2 GPIO3 GPIO4 GPIO5 GPIO6 GPIO7

PTB0/AD0 PTB1/AD1 PTB2/AD2 PTB3/AD3 PTB4/AD4 PTB5/AD5 PTB6/AD6 PTB7/AD7

PTE0/TxD1 PTE1/RxD1 PTE2/CEBi PTE3/MISOo PTE4/MOSIi PTE5/SPICLK

33 30 29 22 31

32 23

28

27

39 38 37 36 35 34 40

46 69

44 43 42 41 24 25 26

52 53 54 55 56 57 58 59

20 21 68 67 66 65

C118 100nF Not Mounted

C104 100nF

16.000MHz

X100

TP104

TP108 TP109 TP110 TP111 TP112 TP113 TP114

C105 100nF

VIN

C106 100nF

V_RF

R100 470K

V_BB

C123 1µF

VDDA

C101 6.8pF

C100 6.8pF

PTB0/AD0 PTB1/AD1 PTB2/AD2 PTB3/AD3 PTB4/AD4 PTB5/AD5 PTB6/AD6 PTB7/AD7

TP100 TP101 TP102 TP103

TP122

MBR0520LT1

D100

MBR0520LT1 Not Mounted

MBR0520LT1 Not Mounted

S100-3 MFP461N-RA

D108

D109

R124 0R Not Mounted

VCC

1 3 2

V_USB

9 8 7

Note: R137 shall be mounted, if SP3223EUCY is used as IC102

1

C

C

A

2

C107 1µF

1.5nH

L103

5

2

4

GND

NC

OUT

2

4

5

3 VOUT

LCD_Enable Register_Select Enable Data_Read/Write Data_Line_4 Data_Line_5 Data_Line_6 Data_Line_7

L100 6.8nH Not Mounted

VOUT

L101 3.9nH

R110

1 2 3 MFP461N-RA

S100-1

Q101 MMBT3906LT1 Not Mounted

2 3 4 5

C103 1.2pF Not Mounted

C124 10µF

1 2 3 4 5 6 7 8

BAT2 Jumper_1x2 Not Mounted

VCC

J100 SMA_edge_Receptacle_Female

ANT100 F_Antenna

50_Ohm2

R112 0R Not Mounted

4 5 6

VCC

V_RF

V_BB

C122 100nF Not Mounted

C125 1µF

V_UART

MFP461N-RA

S100-2

R136 27R

R132 0R

R131 0R

±1.5gTriple Axis Accelerometer

Not Mounted

MMA7260Q

EP

N/C g-Select 1 XOUT g-Select 2 YOUT VDD ZOUT VSS Power Save N/C N/C N/C N/C N/C N/C N/C

IC105

R111 0R

17

16 15 14 13 12 11 10 9

RS100 500mA Not Mounted

J106 Jumper_1x2 Not Mounted

R130 0R

BAT1 2P_Connector Not Mounted

VOUT

D107 MBR0520LT1 Not Mounted

R142 100K Not Mounted

C130 3.3µF

D106 MBR0520LT1

1.0K Not Mounted C119 100nF Not Mounted

50_Ohm1

1.0K Not Mounted

R109

VCC 5V

12K Not Mounted

R141

C144 1µF Not Mounted

C127 10µF Not Mounted

LDB212G4005C-001

6

4

1

R126 0R Not Mounted C126 3.3µF Not Mounted

C120 100nF Not Mounted

GND

5V

5

Z100

5V

VCC

2

3

C102 10pF

C121 100nF Not Mounted

1.0K Not Mounted

R108

LCD Part

100_Ohm2

1

LCD_Vo_Supply

Sheet2

100_Ohm1

VIN

Not Mounted

C132 10nF Not Mounted

C133 10nF Not Mounted

IC110 LP38690DTX-3.3

LP2981IM5-3.3

ON/OFF

IN

IC107

Not Mounted

PTB0/AD0 PTB1/AD1 PTB2/AD2 PTB3/AD3 PTB4/AD4 PTB5/AD5 PTB6/AD6 PTB7/AD7

1.5nH

L102

GND

NC

OUT

LP2981IM5-5.0

ON/OFF

IN

IC108

C128 10µF Not Mounted

3

1

3

1

GND 2

1 2

Figure 5: 13213 SED Reference Design Schematic

3

TP123

2

TP124

50_Ohm3 1

TP126

3

2 1 1

TP115

2

TP116 1

TP120

2

TP118

ZigBee and Low Cost Wireless Networks 45

Antenna design can be a complex issue, particularly for digital

Memory requirements for sensing and control applications are

designers who have limited to no experience in RF design.

typically 8 KB of flash with 512B of RAM or as low as 4 KB of

Typically, designers will take into account such factors as

flash with 256B of RAM. Flash read, program or erase over the

selecting the correct antenna, antenna tuning, matching,

full operating voltage and temperature are essential.

gain/loss and knowing the required radiation pattern. It is advisable to gain a basic knowledge of antenna factors through application notes provided by the transceiver vendor. However, most digital engineers prefer to consider working with a vendor solution where antenna design is provided. This allows them to focus on the application design. Look for antenna solutions where the antenna design is offered in completed Gerber files, which can be provided directly to the printed circuit board manufacturer for implementation. A vendor who provides such antenna design solutions eliminates the issues associated with good antenna design, good range and stable throughputs in wireless applications. The quad flat no-lead package (QFN) is the optimum small footprint packaging solution for the transceiver portion of a low cost wireless networking subsystem. The packaging takes into consideration the board space limitations often driven by sensing and control solutions. Size is particularly important in the case of end nodes that are often battery operated with limited implementation space.

A variety of operation modes provides precise control over power consumption, a key feature for extending battery operated solutions. Look for MCUs that support normal operating (run) mode, active background mode for on-chip debug, a variety of stop modes (bus and CPU clocks are halted) and wait mode alternatives. Consider a microcontroller with an internal clock source module containing a frequency-locked-loop (FLL) controlled by an internal or external reference with precision trimming of internal reference that allows 0.2 percent resolution and 2 percent deviation over temperature and voltage. The internal clock source module should support bus frequencies from 1 MHz to 10 MHz. MCUs with selectable clock inputs for key modules provide control over the clock to drive the module function. As well, look for MCUs with a low-power oscillator module with software selectable crystal or ceramic resonator in the range of 31.25 KHz to 38.4 KHz or 1 MHz to 16 MHz that supports external clock source input up to 20 MHz. It is essential that the chosen MCU offer system protection,

Microcontroller Multiple alternatives exist in selecting a sensing and control implementation scheme. Some designers select a system in package (SiP) or platform in package™ (PiP) which includes transceiver and MCU functionality in a single package. However, should you opt for a stand-alone transceiver and

including such options as watchdog computer operating properly (COP) reset with an alternative to run from a dedicated 1 KHz internal clock source or bus. Other must-have system protection features include low-voltage detection with reset or interrupt, illegal opcode detection with reset, illegal address detection with reset and flash block protection.

microcontroller configuration, you gain the flexibility to choose

A variety of embedded peripherals will ease the implementation

from a variety of MCUs to mix and match for multiple end

of your application. An 8-channel, 10-bit analog-to-digital

product configurations.

(ADC) converter is recommended for accurate successive

When choosing the latter implementation scheme, appropriate MCU selection requires thorough research. MCU selection depends upon matching the complexity of the sensing and control application with suitable performance factors, memory

approximation. Specific functions should include automatic compare, asynchronous clock source, temperature sensor, internal bandgap reference channel and an ADC that is hardware triggerable using the real-time interrupt (RTI) counter.

configurations and peripheral modules. Often for low cost

Other essential peripherals for sensing and control applications

wireless sensing systems, 8-bit MCUs in the 20 MHz CPU

include: an analog comparator module (ACMP) with an option

operating frequency (10 MHz bus clock) range offer an

to compare internal reference; serial communications interface

easy-to-implement, low-cost alternative which best suits these

module (SCI); serial peripheral interface module (SPI); inter-

applications. Background debugging and breakpoint capability

integrated circuit (I2C) bus module; 2-channel timer/pulse-width

to support single breakpoint (tag and force options) setting

modulator for input capture; output compare; buffered edge-

during in-circuit debug (plus two breakpoints in on-chip debug

aligned PWM or buffered center-aligned PWM; 8-bit modulo

module) offer the preferred debugging environment. Many MCU

timer module with prescaler and 8-pin keyboard interrupt

solutions provide support for up to 32 interrupt/reset sources.

module with software selectable polarity on edge or edge/level modes.

46 freescale.com/beyondbits

There are multiple small foot print MCU packaging options

You also have the option to use a stand alone transceiver

that satisfy sensing and control design requirements. These

and MCU alternative to provide additional design flexibility.

help optimize limited board space, particularly in end node,

For example, the block diagram below is Freescale’s 13192

battery operated functions. A few of the MCU packages that

sensor application reference design for sensing, monitoring and

meet these considerations are low pin-count plastic dual

control subsystems. Completed boards based on this design

in-line (PDIP), quad flat no-lead (QFN), thin shrink small outline

are included in our 13192DSK-A0E (developer’s starter kit) and

(TSSOP), dual flat no-lead (DFN) and narrow body, small outline

13192EVK-SFTE (evaluation kit) development kits (Figure 4).

(NB SOIC) packages.

Supporting files for the above reference designs are available

It is also prudent to consider as part of the MCU selection

via web download. The download folder includes schematics,

hardware and software design tool ease-of-use, documentation

bill of materials, gerber files and other necessary documentation

clarity, reference design and application code availability and

for complete reference design implementation.

other design support offerings. Similarly, on the RF or modem side of the design, an effective integrated development environment (IDE) should include GUI-driven tools with built-in features and utilities that simplify coding and project

Freescale’s Wireless Networking Solutions for Sensing, Monitoring and Control Applications

file management to expedite the design process. Expert tools

We offers an exceptional set of solutions for the digital engineer

that abstract the hardware layer and generate optimized,

who wants to establish a new paradigm in end products. The

MCU-specific C code tailored to the application allow you to

broad portfolio meets the design requirements noted above that

concentrate on application concepts. Fast and easy debug as

are essential to low cost, wireless networking implementations.

well as a flash programming capability need to be considered.

Sample products include:

It is also helpful to have access to features that allow the

• RF modem or transceiver solutions (Simple MAC, 802.15.4

designer to create reusable software components for reuse

MAC and ZigBee), which can be used with a variety of MCUs

between projects.

(MC1319x and MC1320x transceiver families are used with the HCS08 and ColdFire MCU families)

Schematics for Sensing, Monitoring and Control Subsystems A reference design schematic for sensing, monitoring and control subsystems is often of value as an application baseline from which to evolve design specific requirements. As an example of a design using a system in package (SiP) solution, shown below is the schematic for the Freescale 1321x-SRB sensor reference board, which is included in the 1321XDSK (developer’s starter kit), 1321xNSK (network starters kit) and 1321xEVK (ZigBee evaluation kit). The 1321x-SRB includes the Freescale MMA7260Q tri-axis acceleration sensor and,

• Integrated transceiver solutions (Simple MAC, 802.15.4 MAC and ZigBee) with MCU system in package (SiP) solutions (MC1321x SiP family) • Analog components • Sensor components For easy-to-use implementations of ZigBee and other low-cost, low-power wireless networks, Freescale is your resource for reference designs, application notes, hardware development tools and software design tools. For more detailed product information visit us at www.freescale.com/zigbee.

used with the starter kits, helps you set up working networks within a matter of minutes. The board offers a reference design application that is a starting point for sensing application development (Figure 5).

Pattye Brown is a technical marketing engineer and channel marketing liaison at Freescale Semiconductor; she has been with the company for 23 years. She holds a bachelor’s degree in industrial engineering and a masters degree in business administration and marketing.

ZigBee and Low-Cost Wireless Networks 47