Related Manuals for Laird AC4868
Summary of Contents for Laird AC4868
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Page 1: Ontents Revision History
AC4868 868 MHz Transceiver User’s Guide Version 2.0 Americas : +1-800-492-2320 Option 3 Europe : +44-1628-858-940 Hong Kong : +852-2268-6567 x026 www.lairdtech.com/ramp... - Page 2 Corrected EEPROM write command response. 18 September 2007 Internal Release 5 September 2008 Updated to Laird Technologies branding. Clarified Duty Cycle calculations. Updated information on client to client communications. Corrected Read Temperature Command to a max of 0x50. Updated Minimum Baud Rate.
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Page 3: Table Of Contents
Test / 9600 Baud ..........................21 UP_Reset ............................. 21 Command / Data ..........................21 AD In and DA Out ..........................21 In Range .............................. 21 Configuring the AC4868-250 ........................22 AT Commands ............................22 Americas: +1-800-492-2320 Option 3 Laird Technologies Europe: +44-1628-858-940 Hong Kong: +852 2923 0610 www.lairdtech.com/ramp... - Page 4 AC4868 868 MHz Transceiver User’s Manual On-the-Fly Control Commands ......................23 Command Descriptions ..........................24 Enter AT Command Mode ........................24 Exit AT Command Mode ........................24 Status Request ............................. 24 Change Server / Client ......................... 25 Sleep Walk Power-Down ........................25 Sleep Walk Power-Down Wake Up ......................
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Page 5: Overview
AC4868-250 transceivers can operate in a Point-to-Point, Point-to-Multipoint, or Peer-to-Peer architecture. The AC4868-250 utilizes a single channel synchronization allowing all radios to communicate with any radio in range. Optionally any radio can be configured as a Server to provide a synchronization beacon. This beacon is used by the Client radios to determine In Range status and for Auto Destination addressing. -
Page 6: Specifications
AC4868 868 MHz Transceiver User’s Manual PECIFICATIONS Module Specifications Table 1: General Specifications Parameter Description 20 Pin Interface Connector Molex 87759-0030, mates with Samtec SMM-110-02-S-D RF Connector Telegartner J01341C0081, mates with any manufacturer’s MMCX style plug Antenna AC4868-250: MMCX Connector Serial Interface Data Rate Baud rates from 1200 bps to 57.6 kbps... -
Page 7: Electrical Specifications
AC4868 868 MHz Transceiver User’s Manual Electrical Specifications Table 4: Input Voltage Characteristics Signal Name High Min. High Max. Low Min. Low Max. Unit RS485 A/B 2.31 0.99 2.31 0.99 2.31 0.99 2.31 0.99 TEST 2.31 0.99 UP_Reset Command/Data 2.31 0.99... - Page 8 This pin has an internal connection and should be left disconnected. Generic Input pin UP_RESET RESET – Controlled by the AC4868-250 for power-on reset if left unconnected. After a stable power-on reset, a logic High pulse will reset the transceiver.
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Page 9: Theory Of Operation
RF Architecture The AC4868-250 is a single channel radio transceiver. Each unit can be configured as a Server or as a Client. Servers are responsible for sending out beacons and for allow for radios to be configured very simply in a point-to-multipoint network. - Page 10 AC4868 868 MHz Transceiver User’s Manual Command Mode) command. Once in Command Mode, all data received by the radio is interpreted as command data. Command Data can be either EEPROM Configuration or On-The-Fly commands. Figure 1: Pending RF and Data in Buffer Flow...
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Page 11: Duty Cycle Limitations
<10%. This duty cycle is measured as the amount of TX time on, monitored over one hour and relative to a one hour period. Thus for the AC4868-250, the maximum “on” time in an hour cannot exceed six minutes. Radio Operation The AC4868 will transmit data whenever data is present on the serial UART. -
Page 12: Serial Interface
Serial Communications The AC4868-250 is a TTL device which can be interfaced to a compatible UART (microcontroller) or level translator to allow connection to serial devices. UART stands for Universal Asynchronous Receiver Transmitter and its main function is to transmit or receive serial data. -
Page 13: Oem Host Data Rate
AC4868 868 MHz Transceiver User’s Manual OEM Host Data Rate The OEM Host Data Rate is the rate with which the OEM Host and transceiver communicate over the serial interface. Possible values range from 1200 bps to 57,600 bps. Note: Enabling Parity cuts throughput in half and the Interface Buffer size in half. -
Page 14: Flow Control
RF Packet Size. However, if the RF Packet Size is set too large, the transceiver will not be able to send any packets because the AC4868 requires the entire RF packet to be sent in the same hop period (53 ms). -
Page 15: System Timing And Latency
System Throughput When operating as shown below, an AC4868-250 transceiver is capable of achieving the listed throughput. However, in the presence of interference or at longer ranges, the transceiver may be unable to meet the specified throughput. -
Page 16: Software Interface
Range Refresh should not be set to 0x00. Auto Config Parameters The AC4868-250 has several variables that vary by RF mode and architecture. By default, Auto Config is enabled and bypasses the values stored in EEPROM and uses predetermined values for the given operating mode. -
Page 17: Max Power
User’s Manual Max Power Max Power provides a means for controlling the RF output power of the AC4868. Output power and current consumption can vary by as much as ±10% per transceiver for a particular Max Power setting. Contact Laird Technologies for assistance in adjusting Max Power. -
Page 18: Timing Diagrams
AC4868 868 MHz Transceiver User’s Manual IMING IAGRAMS AC 4868-250 Timing Diagrams Figure 4: Addressed Mode with Timeout Figure 5: Addressed Mode with Fixed Packet Length Figure 6: Broadcast Mode with Timeout Americas: +1-800-492-2320 Option 3 Laird Technologies Europe: +44-1628-858-940 Hong Kong: +852 2923 0610 www.lairdtech.com/ramp... - Page 19 AC4868 868 MHz Transceiver User’s Manual Figure 7: Broadcast mode with Fixed Packet Length Americas: +1-800-492-2320 Option 3 Laird Technologies Europe: +44-1628-858-940 Hong Kong: +852 2923 0610 www.lairdtech.com/ramp...
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Page 20: Hardware Interface
Hop Frame signal every time it transmits a timing beacon. The AC4868-250 has an interface buffer size of 256 bytes. If the buffer fills up and more bytes are sent to the transceiver before the buffer can be emptied, data loss will occur. The transceiver prevents this loss by asserting CTS High as the buffer fills up and taking CTS Low as the buffer is emptied. -
Page 21: Test / 9600 Baud
UP_Reset UP_Reset provides a direct connection to the reset pin on the AC4868-250 microprocessor and is used to force a soft reset. For a valid reset, reset must be asserted High for a minimum of 11ms. -
Page 22: Configuring The Ac4868-250
Figure 8: AC5868-250 Configuration Flow AT Commands The AT Command mode implemented in the AC4868-250 creates a virtual version of the Command/Data pin. The “Enter AT Command Mode” Command asserts this virtual pin Low (to signify Command Mode) and the “Exit AT Command Mode”... -
Page 23: On-The-Fly Control Commands
User’s Manual On-the-Fly Control Commands The AC4868-250 transceiver contains static memory that holds many of the parameters that control the transceiver operation. Using the “CC” command set allows many of these parameters to be changed during system operation. Because the memory these commands affect is static, when the transceiver is reset, these parameters will revert back to the settings stored in the EEPROM. -
Page 24: Command Descriptions
AC4868 868 MHz Transceiver User’s Manual Command Name Command (All bytes in Hex) Return (All bytes in hex) Bit 1: GO1 Bit 1: GO1 Write DAC 0xCC 0x24 Update Duty 0xCC Update Duty Cycle Period Cycle Period Set Max Power... -
Page 25: Change Server / Client
AC4868 868 MHz Transceiver User’s Manual Change Server / Client The OEM Host issues this command to change the transceiver mode from Server to Client and vice versa. Command: 0xCC 0x03 Data1 Bytes Returned: Response: 0xCC Firmware Version Data1 Parameters:... -
Page 26: Write Destination Address
AC4868 868 MHz Transceiver User’s Manual Write Destination Address The OEM Host issues this command to the transceiver to change the Destination Address. Note: Only the three Least Significant Bytes of the MAC Address are used for packet delivery. Command:... -
Page 27: Read Adc
AC4868 868 MHz Transceiver User’s Manual Read ADC The OEM Host issues this command to read any of the three onboard 10-bit A/D converters. Because the RF is still active in On-the-Fly Command Mode, the transceiver will not process the command until there is no activity on the network. -
Page 28: Set Max Power
AC4868 868 MHz Transceiver User’s Manual Set Max Power The OEM Host issues this command to limit the maximum transmit power emitted by the transceiver. This can be useful to minimize current consumption and satisfy certain regulatory requirements. The radios are shipped at maximum allowable power. -
Page 29: Eeprom Byte Write
AC4868 868 MHz Transceiver User’s Manual EEPROM Byte Write Upon receiving this command, a transceiver will write the data byte to the specified address but will not echo it back to the OEM Host until the EEPROM write cycle is complete (up to 10 ms). -
Page 30: Eeprom Parameters
AC4868 868 MHz Transceiver User’s Manual EEPROM P ARAMETERS The OEM Host can program various parameters that are stored in EEPROM which become active after a power-on reset. The table below gives the locations and descriptions of the parameters that can be read/written by the OEM Host. - Page 31 AC4868 868 MHz Transceiver User’s Manual Parameter EEPROM Length Range Default Description Address (bytes) Transmit Retries 0x4C 0x01 – 0x10 Maximum number of times a packet is sent out 0xFF when Addressed packets are selected. Broadcast 0x4D 0x01 – 0x04...
- Page 32 AC4868 868 MHz Transceiver User’s Manual Parameter EEPROM Length Range Default Description Address (bytes) Destination ID 0x70 0x00 – 0xFF Specifies destination for RF packets 0xFF System ID 0x76 0xE3, 0xFF Similar to network password. Radios must have 0xFF the same system ID to communicate with each other.
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Page 33: Dimensions
Mechanical Drawings Interface Connector - 20 pin OEM Interface connector (Molex 87759-0030, mates with Samtec SMM-110-02-S-D MMCX Jack - Antenna Connector (Johnson Components 135-3711-822) Figure 9: AC4868-250 (with MMCX connector) Mechanical Americas: +1-800-492-2320 Option 3 Laird Technologies Europe: +44-1628-858-940 Hong Kong: +852 2923 0610... -
Page 34: Ordering Information
Developer Kit Part Numbers All of the above part numbers can be ordered as a development kit by prefacing the part number with “SDK-”. As an example, part number AC4868-250M can be ordered as a development kit using the part number: SDK-AC4868- 250M. -
Page 35: Compliancy Information
Approved Approved Antenna List The following antennas are approved for use with the AC4868-250 as identified. The OEM is free to choose another vendor’s antenna of like type and equal or lesser gain as a listed antenna and still maintain compliance. -
Page 36: Country Restrictions
The exclamation point included with the CE mark denotes that the equipment has restrictions in certain countries. Following is a list of countries having restrictions on the AC4868 and a description of those restrictions. The OEM is responsible for ensuring that these restrictions are met. -
Page 37: Declaration Of Conformity
User’s Manual Declaration of Conformity Laird Technologies has issued a Declaration of Conformity for the AC4868-250M transceiver module concerning emissions, EMC, and safety. The Declaration of Conformity is a document that lists the product name and band of use and must appear in the OEM user’s manual. -
Page 38: Appendix I: Sample Power Supply
OWER UPPLY Below is a simple switching power supply that provides enough current to easily power any Laird Technologies OEM module. It utilizes low cost, off the shelf components that fit into a small area. This supply has an input voltage range of +6 volts to +18 volts and will output +3.4 volts at 1.5 amps. -
Page 39: Schematic
AC4868 868 MHz Transceiver User’s Manual Schematic PCB Layout Americas: +1-800-492-2320 Option 3 Laird Technologies Europe: +44-1628-858-940 Hong Kong: +852 2923 0610 www.lairdtech.com/ramp... - Page 40 AC4868 868 MHz Transceiver User’s Manual Americas: +1-800-492-2320 Option 3 Laird Technologies Europe: +44-1628-858-940 Hong Kong: +852 2923 0610 www.lairdtech.com/ramp...
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Page 41: Appendix Ii: 5V To 3.3V Levels
3.3V L PPENDIX EVELS All inputs on the AC4868-250 are weakly pulled high via 10 kohm resistors. The AC4868-250 has 3.3V only inputs. Some of the most common voltage conversion methods are described below. Voltage Level Conversion ICs This is the easiest and most efficient method. Laird Technologies recommends the TI SN74LVC244A Octal Buffer/Driver.
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