RFM DNT24C Integration Manual Download

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DNT24 Integration Guide - 10/19/11

DNT24 Series

2.4 GHz Spread Spectrum

Wireless Transceivers

Integration Guide

Summary of Contents for DNT24C

Page 1: ...com Technical support 1 678 684 2000 Page 1 of 83 2011 by RF Monolithics Inc E mail tech_sup rfm com DNT24 Integration Guide 10 19 11 DNT24 Series 2 4 GHz Spread Spectrum Wireless Transceivers Integration Guide ...

Page 2: ... The DNT24 has been designed to operate with any dipole antenna of up to 12 dBi of gain any corner reflector antenna of up to 14 dBi gain any patch antenna of up to 12 dBi gain or any chip antenna of up to 1 7 dBi gain The antenna s used for this transmitter must be installed to provide a separation distance of at least 20 cm from all persons and must not be co located or operating in conjunction ...

Page 3: ...t choisir le type d antenne et son gain de sorte que la puissance isotrope rayonnée équivalente p i r e ne dépasse pas l intensité nécessaire à l établissement d une communication sat isfaisante This device complies with Industry Canada licence exempt RSS standard s Operation is subject to the following two conditions 1 this device may not cause interference and 2 this device must accept any inter...

Page 4: ...Parameters 17 4 2 Configuring a Basic Point to Point System 18 4 3 Configuring a Basic Point to Multipoint System 18 4 4 Configuring a Customized Point to Point or Point to Multipoint System 18 4 5 Configuring a Store and Forward System 20 4 6 Slot Buffer Sizes Number of Slots Messages per Hop and Hop Duration 21 5 0 DNT24 Application Interface Configuration 23 5 1 Configuring the Serial Port 23 5...

Page 5: ...tocol formatted Message Examples 57 7 5 1 Data Message 57 7 5 2 Configuration Messages 58 7 5 3 Sensor Message 58 7 5 4 Event Message 59 8 0 DNT24DK DNT24ADK Developer s Kits 60 8 1 Kit Contents 60 8 2 Additional Items Needed 60 8 3 Developer s Kit Default Operating Configuration 60 8 4 Developer s Kit Hardware Assembly 61 8 5 Utility Program 62 8 6 Initial Kit Operation 62 8 6 1 Serial Communicat...

Page 6: ...atile memory stores DNT24 configura tion when powered off Five mile plus range with omnidirectional antennas antenna height dependent Selectable 10 or 63 mW transmit power levels Transparent ARQ protocol with data buffering ensures data integrity Automatic I O event reporting mode simplifies application development Analog and Digital I O supports wireless sensing applications I O binding mode prov...

Page 7: ...ion Direct sequence spread spectrum is produced by multiplying the transmitted data stream by a much faster noise like repeating pattern The ratio by which this modulating pattern exceeds the bit rate of the base band data is called the processing gain and is equal to the amount of rejection the system affords against narrow band interference from multipath and jammers Transmitting the data signal...

Page 8: ...cally takes several seconds In summary frequency hopping systems generally feature greater coverage and channel utiliza tion than comparable direct sequence systems Of course other implementation factors such as size cost power consumption and ease of implementation must also be considered before a final radio design choice can be made 2 0 DNT24 System Overview A DNT24 radio can be configured to o...

Page 9: ...works Networks in a store and forward system form around the base and each router The base and the routers are referred to as the parents of the networks they form The rest of the radios in each network are referred to as child radios Note that a router is a child of the base or another router while being the parent of its own network Each network parent trans mits beacons to allow child radios to...

Page 10: ... base mode beacon can include up to 8 messages addressed to one or more child radios The number of slots is chosen accommodate the number of children that need to send messages each hop S y s t e m N e t w o r k C o n t r o l M e s s a g e s t o N e t w o r k C h i l d r e n B a s e M o d e B e a c o n E x a m p l e D N T 2 4 C o m m u n i c a t i o n F r a m e A s s i g n e d S l o t O p e n S l ...

Page 11: ... store and forward system however the base mode network IDs of all routers must be set to different values between 0x00 to 0x3F If the base mode network ID of 0x00 is assigned to a router the base must be assigned an unused base mode network ID between 0x01 and 0x3F Leaving all parent network IDs in a store and forward system set to the default value of 0xFF allows networks to automati cally form ...

Page 12: ...hopping is optional and when frequency hopping is used there is no minimum requirement on the number of hopping channels that can be used As dis cussed in Section 7 4 2 there are two 5 channel hopping patterns that can be used to help minimize link ing time All DNT24 s in a system must be preset to one of these 5 channel hopping patterns in order to achieve fast linking Note that the 5 channel hop...

Page 13: ...ed as an RS485 enable function The serial communication port can be configured with baud rates from 1 2 to 250 0 kbps with 9 6 kbps the default baud rate The DNT24 communication port transmits receives 8 bit data with a choice of even odd or no parity and 1 or 2 stop bits The default configuration is no parity and one stop bit See Section 5 1 for recommendations on configuring the communication po...

Page 14: ... SPI master mode signal connections and Figure 3 2 2 shows the SPI master mode timing S S S C L K M O S I M I S O S P I B i t C l o c k C o m m a n d t o S l a v e D a t a f r o m S l a v e D N T 2 4 S P I M a s t e r M o d e O p e r a t i o n Figure 3 2 2 In SPI slave mode the host can stream data into DNT24 at up to 250 kbps provided the host suspends clocking within 10 bytes following a low to ...

Page 15: ...egins to clock out the data which can include several messages 6 The host continues to clock out data until a 0x00 byte occurs in the byte stream where a 0xFB start of message would be expected 7 The host has now clocked out all messages and the 0x00 is discarded 8 The host sets HOST_RTS and SS high to allow the DNT24 to signal DAV the next time it has data Note that the DAV signal can go low befo...

Page 16: ...e negative sensor inputs are connected to ground and the positive sensor inputs are connected to ADC0 ADC1 and ADC2 respectively Single ended measurements are unsigned 11 bit values In differential mode one or two sensor inputs can be measured as 12 bit signed values The first differential measurement is the differ ence between the voltage on ADC1 and the voltage on ADC0 and is referred to as the ...

Page 17: ...nt report DAC1 will output the voltage read by ADC1 in the last received event report I O binding is used to transmit switch positions or analog signals from one location to another Note that I O binding cannot be used in a DNT24 when SPI slave mode is enabled or differential ADC mode is used See Section 5 4 for recommendations on configuring I O event reporting and binding and Sections 7 4 6 and ...

Page 18: ...ceMode parameter in Bank 0 to 0x01 2 If the host application driving the base will individually communicate each remote set the Proto colMode parameter in Bank 4 of the base to 0x01 This step is not required if messages from the base to the remotes will always be broadcast and or the base does not need to know the MAC address of the remote sending a message 3 Set the MemorySave parameter in Bank 0...

Page 19: ...ystem radios Note that if the application data includes addressing information for individual remote hosts the DNT24 broad cast mode can be used instead of the DNT24 protocol mode 9 If using transparent serial mode in the system a Set the remote transparent destination address in the RmtTransDestAddr parameter Bank 0 in each remote if the destination is not the base the base address is the default...

Page 20: ...plyTimeout parameter in Bank 1 The default is 16 hops See Section 7 4 2 for parameter details 17 Configure the registration timeout on the base by setting the RegistryTimeout parameter in Bank 1 The default timeout is 50 hops See Section 7 4 2 for a discussion of this parameter 18 Load an optional friendly description in each system radio in the UserTag parameter Bank 0 4 5 Configuring a Store and...

Page 21: ...an the BSS to a maximum of 114 bytes The base can po tentially send more than one message per beacon up to the limit set by its MsgsPerHop parameter value Each message in the BSS buffer occupies nine header bytes plus the payload For example the base can send three messages per hop when the BSS is 90 bytes provided the total payload bytes in the three messages is 72 bytes or less slot size 90 buff...

Page 22: ...ns The required BSS and RSS for protocol formatted messages sent over the wireless link are shown in Table 7 3 1 For example the BSS and RSS size required for a TxData protocol formatted message is three bytes less than the value in the length byte field of the formatted message The default BSS is 40 bytes number of slots is 3 and hop duration is 20 ms These parameter settings provide a 25 byte RS...

Page 23: ...uration DNT24 modules include a comprehensive set of application interfaces and related options that support a wide range of applications including wireless RS232 485 cable replacements wireless sensor networks wireless alarm systems and industrial remote control applications Recommended configuration steps for each application interface are discussed in Sections 5 1 through 5 7 below 5 1 Configur...

Page 24: ...ADC_EXT_REF input If ADC operation is not needed setting this parameter to 0x03 disables ADC operation reducing current consumption 2 Select the ADC mode either single ended or differential by setting the AdcDiffMode parameter in Bank 6 The default is single ended ADC operation 3 If differential ADC mode is selected set the desired ADC preamplifier gain for each ADC channel with the AdcGainCh0 and...

Page 25: ... support contact RFM technical support 5 5 Configuring I O Event Reporting and I O Binding 1 Select the analog digital and timing events that will trigger an I O event report by setting the respective bits in the IoReportTrigger parameter in Bank 6 The default is no triggers set 2 Configure the trigger behavior bits in the GpioEdgeTrigger parameter Bank 6 for each GPIO input selected to generate a...

Page 26: ...sleep mode as desired in each remote by setting the SleepModeEn parameter in Bank 0 to 1 2 Configure the timeout for a remote to attempt to link to its parent when triggered awake This is done by setting the WakeLinkTimeout parameter in Bank 0 The default timeout is 5 seconds 3 Configure the maximum time a remote in sleep mode will remain awake following linking receiving an ACK processing a messa...

Page 27: ... DNT24 modules operate in the 2 4 GHz MHz ISM band There are 12 selectable hopping patterns providing compatibility with frequency allocations in most regions of the world DNT24 modules also has two selectable RF output power levels 10 mW and 63 mW The DNT24 modules provide a variety of hardware interfaces There are two serial ports plus one SPI port Either the primary serial port or the SPI port ...

Page 28: ... Peer to Peer and Store and Forward Access Scheme Ad Hoc TDMA ADC Input Range 0 2 7 V ADC Input Resolution 12 bits ADC Sample Rate 100 Hz Signal Source Impedance for ADC Reading 10 K ADC External Reference Voltage Range 1 0 2 7 V DAC Output Range 0 3 3 V DAC Output Resolution 12 bits Primary and Diagnostic Serial Port Baud Rates 1 2 2 4 4 8 9 6 19 2 14 4 28 8 38 4 57 6 115 2 230 4 250 0 kbps Maste...

Page 29: ...function is UART SPI flow control input The host sets this line low to allow data to flow from the module on the RADIO_TXD pin When the host sets this line high the module will stop sending data to the host 9 DAC0 O 12 bit DAC 0 output Full scale can be referenced to the voltage at pin 25 or the 3 3 V regulated module bus voltage 10 GPIO2 I O Configurable digital I O port 2 Same configuration opti...

Page 30: ...gurations for connection to the RFIO port A short U FL coaxial cable can be used to connect the RFIO port directly to an antenna In this case the antenna should be mounted firmly to avoid stressing the U FL coaxial cable due to antenna mounting flexure Alternately a U FL coaxial jumper cable can be used to connect the DNT24 module to a U FL connector on the host circuit board The connection betwee...

Page 31: ...ns must be protected from electrical transients on the power supply and I O lines This is especially important in outdoor installations and or where connections are made to sensors with long leads Inadequate transient protection can result in damage and or create a fire and safety hazard 6 6 Interfacing to 5 V Logic Systems All logic signals including the serial ports on the DNT24 are 3 3 V signal...

Page 32: ...P or DNT24PA depending on the model used This device complies with Part 15 of the FCC Rules Operation is subject to the following two con ditions 1 This device may not cause harmful interference and 2 this device must accept any interfer ence received including interference that may cause undesired operation WARNING This device operates under Part 15 of the FCC rules Any modification to this devic...

Page 33: ...is bit is set to indicate a message is a reply Bits 3 0 Type these bits indicate the message type As indicated the lower four bits 3 0 specify a message type Bit 4 indicates that the message is a reply A reply message has the original command type in bits 3 0 with Bit 4 set to one Bit 5 indicates an event message Arguments vary in size and number depending on the type of message and whether it is ...

Page 34: ...TxData from Host length value 0x03 0x15 TxDataReply from Radio 0x01 0x06 GetRemoteRegister from Host 0x03 0x16 GetRemoteRegisterReply from Radio 0x14 0x07 SetRemoteRegister from Host 0x13 0x17 SetRemoteRegisterReply from Radio 0x04 0x26 RxData from Radio length value 0x03 0x27 Announce Error from Radio 0x07 0x28 RxEvent from Radio 0x0D Table 7 3 1 EnterProtocolMode command and reply format details...

Page 35: ...e 0x02 Packet Type 0x02 DeviceReset 0x03 Reset Type 0x00 Normal Device Reset 0x01 Reset to Serial Bootloader 0x02 Reset to Over the Air Bootloader Table 7 3 5 Device Reset Reply Byte Offset Field Description 0x00 Start Of Packet 0xFB Indicates start of protocol formatted message 0x01 Length 0x01 Number of bytes in message following this byte 0x02 Packet Type 0x12 DeviceResetReply Table 7 3 6 GetRe...

Page 36: ...gth 0x05 to 0x20 Number of bytes in message following this byte 0x02 Packet Type 0x04 SetRegister 0x03 Register Offset Register offset in its bank 0x04 Register Bank Register bank number 0x05 Register Size Register size in bytes 0x06 0x15 Register Value Register value all bytes in the register only one parameter at a time Table 7 3 9 Set Register Reply Byte Offset Field Description 0x00 Start of P...

Page 37: ...Length 0x07 Number of bytes in message following this byte 0x02 Packet Type 0x06 GetRemoteRegister 0x03 0x05 Destination MAC Address Destination MAC address in Little Endian byte order 0x06 Register Offset Register offset in its bank 0x07 Register Bank Register bank number 0x08 Register Size Register size in bytes only one parameter at a time wrong register size will produce an error response Tabl...

Page 38: ... Field Description 0x00 Start of Packet 0xFB Indicates start of protocol formatted message 0x01 Length 0x06 Number of bytes in message following this byte 0x02 Packet Type 0x17 SetRemoteRegisterReply 0x03 Status Error status 0x00 no error 0xE1 invalid argument 0x04 0x06 Originator MAC Address Originator s MAC address in Little Endian byte order 0x07 RSSI Packet RX power in dBm 128 to 126 or 127 if...

Page 39: ...t MAC Address MAC address of parent in Little Endian byte order Table 7 3 19 Exit Announcement Byte Offset Field Description 0x00 Start of Packet 0xFB Indicates start of protocol formatted message 0x01 Length 0x03 Number of bytes in message following this byte 0x02 Packet Type 0x27 Indicates this is an Announce Error message 0x03 Announce Status 0xA4 Exited network 0x04 Network ID ID of network th...

Page 40: ...dings Bit Field GPIO0 GPIO5 indicating GPIO readings 0x08 0x09 ADC0 Reading ADC0 Reading 0x0000 0x0FFF in Little Endian byte order 0x0A 0x0B ADC1 Reading ADC1 Reading 0x0000 0x0FFF in Little Endian byte order 0x0C 0x0D ADC2 Reading ADC2 Reading 0x0000 0x0FFF in Little Endian byte order 0x0E 0x0F Event Flags Bit Field Indicating which events have occurred Bit 0 GPIO0 Triggered Bit 1 GPIO1 Triggered...

Page 41: ...0x000000 Base 0x00 0x2C Store ForwardEn R W 0x01 0 1 0 disabled 0x00 0x2D BaseModeNetID R W 0x01 1 63 255 0xFF 0x00 0x2E HeartbeatIntrvl R W 0x02 0 65535 0xFFFF disabled 0x00 0x30 SystemId R W 0x01 0 255 0 0x00 0x31 EndToEndAckEnable R W 0x01 0 1 0 disabled 0x00 0x32 LinkRetryInterval R W 0x02 0 65535 0 off 0x00 0x34 FastBeaconCount R W 0x02 0 65535 0 off 0x00 0x35 FastBeaconTrig R W 0x01 0 255 0 ...

Page 42: ...hat a child radio is allowed to join This parameter is used to provide more robust message routing when setting the Par entNwkID to its 0xFF wildcard value is not appropriate The valid range of this parameter is 0x00 to 0x3F plus 0xFF Rather than specifying wildcard operation setting the AltParentNwkID to 0xFF disables the selection of an alternate parent This parameter is applicable only to remot...

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