The information presented in this document is strictly confidential and contains trade secrets
and other confidential information that are the exclusive property of Connected Holdings
The AR-2GM is a self-Contained vehicle tracking device that combines GPS location with
GSM/GPRS connectivity.
The AR-2GM appears to a user or a server application as a single endpoint device. It can be
queried, updated and configured either through a serial connection, or an over the air GPRS
IP connection, or through SMS messaging. The AR-2GM presents itself over these
connections as an enhanced cellular modem with attached functional elements. These
elements include:
GPS location engine
2 General Purpose Bidirectional I/O (GPIO) pins
1 Relay drive pin output
Serial UART port
Input voltage monitor (optional)
Timers
Watchdog lockup protection (Dedicated watchdog circuit is optional)
Factory load option for motion detection
Access to these elements and general purpose interfaces is done through an extended AT
command set as defined herein.
Application scene:
This product will be designed based on the 2G wireless data/MT6261 Baseband chipset,
which includes GPS functionality, ARM CPU and GPRS protocol. This baseband internal
connection 4M serial flash, GSM 850M/1900M RF Transceiver &GPS receiver, and RF Front
end circuit.
The device will use one dual band antenna(GSM850&PCS1900)and one dedicate
GPS antenna.
1.9GHz Support for 12 class GPRS
Internal Antenna [850M&1900M]
The AR-2GM provides support for specialized hardware features through extended AT
commands. The features supported include the following.
GPS
The major functionality of the GPS module is to compute the correlation results between the
incoming signal and the selected PRN code based on certain Carrier Doppler Frequency,
Code Doppler Frequency, code phase, carrier phase, and the particular satellite the module is
tracking or acquiring.
GPIO
Two GPIO pins, GP1 and GP2, are presented to the external environment on the main
connector. They are general purpose bidirectional lines capable of providing system interrupts
LED
Function
Status
Red
GPS
On: GPS satellites acquired and Locked
Flash Slow: GPS satellite search is in progress
Off: No power or GPS subsystem fault
Green
GSM/GPRS
Connection
On: Indicates GPRS connection is made
Flash Slow: GPRS subsystem initialized but no connection
Flash Fast: GPRS initialization in process
Off: No power or GSM subsystem fault
to generate a report or drive logic levels to external devices. These lines are 2.8V logic level
and are 16V tolerant. These pins default to input. GP1 is pulled down representing 0 when
disconnected; GP2 is pulled up representing logical 1 when disconnected. They should be
asserted to a known value if used. GP1 is intended to use for Ignition Sensing.
LED’s
Two LED status indicators are provided to verify correct installation and operation. The status
LEDs are color coded and directly convey the status of the cellular and GPS subsystems as
described in the table below. Their valid operation also indicates operational status and
power.
The AR-2GM provides user control allowing the LEDs to be extinguished once installation is
verified. This feature reduces power and further conceals the AR-2GM Tracker from
untrained parties wishing to defeat its operation.
UART
A UART port is provided for AT command and data interaction and optionally for application
specific control.
Relay Driver
A 500mA sink capable output pin is provided. This pin is meant to drive a relay coil indented
to interrupt the starter solenoid relay for the ignition circuit to a car.
Battery Monitor
The battery monitor is internal analog input scaled such that the DC value of the power input
pin to the AR-2GM system is measured. This value is scaled to span the most significant 8
bits of the A/D and consequently covers a scale from 0 to 25.5 Volts.
Timers
Timers resident on the GSM baseband chip generate periodic interrupts for power down
wakeup, watchdog support, report generation and other timer related functions. Report timers
are supported by related AT command and cause generation of periodic reports.
Watchdog
MT6261D chipset provide internal software Watchdog, and a physically dedicate Watchdog
The code domain power in each inactive code channel
shall be 23 dB or more below the total output power
measured on both the I and Q data channel combined.
Time reference
±1.0uS
Waveform quality
>0.944
Range of open loop output
power
(test1:-25dBm/1.23MHz)-47.7±9.5dBm
(test2:-60dBm/1.23MHz)-7.7±9.5dBm
(test3:-93.5dBm/1.23MHz)20.3±9.5dBm
Motion Detect (Option)
A factory populates option for motion detector is provided. If populated at the time the
AR-2GM is manufactured, this option will work with firmware power down options to keep
the AR-2GM in a very low power down state until motion is detected. Upon wakening, a
report can then be generated.
The code domain power in each inactive code channel
shall be 23 dB or more below the total output power
measured on both the I and Q data channel combined.
The AR-2GM supports OTA field upgrades of the AR-2GM resident application. An over the
air TFTP (Trivial File Transfer Protocol) connection is made over a UDP/IP connection. A
replacement file is then transferred from a server to the AR-2GM and that file replaces the
previous application image.
3.3 Auto Execute
The Auto Execute Utility copies the contents of file system.exf into system executable RAM
and executes it from there. This file is the factory default application. Another file named
custom.exf can be loaded into the file system.
Auto Execute will look first for a file named update.exf and load and execute that in place of
custom.exf if it exists. If update.exf executes successfully, the previous copy of custom.exf is
deleted from the file system and update.exf is renamed to custom.exf.
3.4 Power Modes
The AR-2GM device supports several power modes that are set by the power mode command.
In full power mode the GPS is active and the cellular subsystem will maintain a persistent
cellular connection whenever service is available. IP connection is maintained according to
the configuration of the device.
The device can be put in low power mode whenever it runs on a backup battery or if the
external battery is low or if it is not moving. In low power mode the GPS is not running and
Any hardware or software reset will return the device to full power mode.
3.5 AT Command
AR-2GM commands are AT extensions specific to AR-2GM devices. They are closely based
on commands that are as similar as possible to other industry common devices and are
essentially subsets of standard AR-2GM commands. Common commands used with GPRS
modems supporting IP connectivity are not included within the AR-2GM command set
extensions. These commands are left in their native structure, as defined by the respective
baseband GSM chip supplier which product already in use.
Command Summary
The following commands are specific to the AR-2GM. They are organized by categories.
Event Setting Commands
The following set of commands enables/disables reporting of the various events and state
transitions that take place in the system. The event setting commands typically include
trigger(s) that indicate what event or state transition would cause an event report to be sent.
Often state transitions also qualified with “debounce” time to prevent various flickers and
intermittent state transitions. Examples are: (1) state change of an input pin; (2) crossing a
geo-fence line for a brief period of time and then crossing it back.
As a general rule every event and state transition has its own unique event ID that is reflected
in the report triggered by the said event. Refer to Table 2 – Events for the complete list of
event ID’s. Those default event ID’s can be changed by the user to accommodate specific
server implementations, by explicitly specifying what they are in the respective commands.
As an example, all trip related events can be mapped to the same event ID, so there is no need
to parse the specific event trigger. Following is a list of event setting commands:
42. AT+XCPCCDMA PRL Configuration (CDMA devices only)
43. AT+XDNSPDNS renew Periodically
44. AT+XKAKeep Alive
45. AT+XPSTPacket Session Timeout
46. AT+XRSTPReset Periodically
Configuration Commands
Configuration commands control various parameter settings of the device. For convenience
they are grouped into topical settings. Following is a list of configuration commands:
Communication related settings
47. AT+XAPNSet APN (GSM devices only)
48. AT+XCSWCellular Session Watchdog
49. AT+XIPSet target server IP address and port number
50. AT+XLPORTSet Local IP port number
51. AT+XMIPSet Maintenance server IP address and port number
52. AT+XPRPPxP Renewal Policy
53. AT+XSMSDSMS Destination
54. AT+XSMSSSMS Source
55. AT+XSPIPSet Serial Port (A-UART) IP address and port number
56. AT+XUIPSet Update server IP address and port number
Information commands simply output various data regarding the current status of the device.
They are mostly useful for troubleshooting. Following is a list of information commands:
The AR-2GM captures data and forms a report record with that data. A report is a data
structure containing all of the sensory and other typically useful data on the device. Reports
are generated in response to specified events, such as periodic timeout, speed threshold,
geo-fence crossing, etc., or in response to a Report Now command (AT+XRN).
Report Queuing
If a report trigger occurs while UDP connection is unavailable, it will be queued until
connection becomes available and transmitted at such time. The only way report(s) can be lost
is if too many reports are queued and the report-queue is overflowing. In such case the earliest
report(s) will be discarded. The size of the queue can be configured via the Report Queue
(AT+XRPQ) command.
Ack’ed Mode
UDP is not a 100% reliable connection and occasional reports or command/responses may be
lost. Since all commands have responses, the server can repeat any command to which there
is no response. In order to assure reliable reception of reports, Arsenal devices can be
configured either in Normal or Ack’ed mode to send the reports. In the Normal mode the
reports are simply sent “as is” with no acknowledgment from the server. In the Ack’ed mode
every report sent is expected to be acknowledged by the server by sending back an ACK
message back. If acknowledgement is not received within the specified timeout, the report is
re-sent. If the report is not acknowledged after the specified number of attempts, it is queued.
If acknowledgement is received after the report is queued (i.e. past timeout of the last attempt),
it is ignored.
Report is not considered “complete” until its acknowledgement is received. Thus, if report X
is sent and report X+1 is triggered while waiting for acknowledgement of X, report X+1 will
be queued until such acknowledgement is received and only then sent. The Arrow will
attempt to re-send queued report(s) every time a new report is triggered. If there is more than
one report queued, the reports will attempt to be sent in the order of triggering and only once
the report is acknowledged, the next report is attempted. This assures that reports are sent and
received in order.
Ack’ed mode assures that all reports are received, but adds overhead in time and data. Report
that is not acknowledged is sent again and eventually will be queued and sent again. The
number and frequency of re-tries is configurable via the Report Acknowledgement command
(AT+XRPA).
Event Report Format
Reports can be generated in either an ASCII representation of hex or as actual binary encoded
hex. The reporting format is selected via Report Format (AT+XRPF) command. Note that
while the logical content of the report is the same in both representations, the size for an
ASCII report is twice the size of actual numbers of bytes compared to binary representation.
3.6 Reset
There are a number of resets available on the device. Soft reset resets the baseband only by
using an internal watchdog, while hard reset power cycles the whole device. There is also an
option to reset the GPS sub-system only.
3.6.1 Context Preservation
When a reset is caused by the Network Watchdog or by the Reset command (modes 0,1), the
context of the system is being preserved and is restored after the reset. The context includes
all the periodic timers, the report queue, the odometer, etc. This allows to reset the unit as a
troubleshooting measure either periodically or due to Network Watchdog without losing
reports that are already in the queue or are pending on running timers. Note that the reset
process may cause 1-2min of inaccuracy in the timers and should not be considered as very
precise.
3.7 Startup Banner
After a reset a startup banner is printed through the UART only. The format and content of
the banner shown below:
This equipment has been tested and found to comply with the limits for a Class B digital device,
pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable protection
against harmful interference in a residential installation. This equipment generates uses and can
radiate radio frequency energy and, if not installed and used in accordance with the instructions,
may cause harmful interference to radio communications. However, there is no guarantee that
interference will not occur in a particular installation. If this equipment does cause harmful
interference to radio or television reception, which can be determined by turning the equipment off
and on, the user is encouraged to try to correct the interference by one or more of the following
measures:
-- Reorient or relocate the receiving antenna.
-- Increase the separation between the equipment and receiver.
-- Connect the equipment into an outlet on a circuit different from that to which the receiver is
connected.
-- Consult the dealer or an experienced radio/TV technician for help.
This device complies with part 15 of the FCC Rules. Operation is subject to the following two
conditions:
(1) This device may not cause harmful interference, and (2) this device must accept any
interference received, including interference that may cause undesired operation.
Changes or modifications not expressly approved by the party responsible for compliance could
void the user's authority to operate the equipment.
RF Exposure Warning Statements:
The antenna(s) used for this transmitter must be installed to provide a separation distance of at
least 20 cm from all persons during the normal operations.
IC STATEMENT
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 interference, including interference that may cause undesired operation of the
device.
Le présent appareil est conforme aux CNR d'Industrie Canada applicables aux appareils radio
exempts de licence. L'exploitation est autorisée aux deux conditions suivantes : (1) l'appareil ne
doit pas produire de brouillage, et (2) l'utilisateur de l'appareil doit accepter tout brouillage
radioélectrique subi, même si le brouillage est susceptible d'en compromettre le fonctionnement.
In order to avoid the possibility of exceeding the IC radio frequency exposure limits, human
proximity to the antenna shall not be less than 20cm (8 inches) during normal operation.
Afin d'éviter la possibilité de dépasser les limites d'exposition aux fréquences radio de la IC
CNR102, la proximité humaine à l'antenne ne doit pas être inférieure à 20 cm (8 pouces) pendant
le fonctionnement normal.