Abstract:
A system controllable by an external microcontroller via an interface external to the system includes a radio module, and a GPS receiver. The radio module is adapted to 1) pass messages received via the interface to the GPS receiver via an internal interface, and 2) to receive messages from the GPS receiver via an internal interface and pass them further to the external interface.

Description:
FIELD OF TECHNOLOGY 
     The present disclosure relates to systems controllable by an external microcontroller via an interface and comprising a radio module and a GPS receiver. 
     BACKGROUND 
       FIG. 1  shows a system  100  comprising a subsystem  10  further comprising a radio module  12  and a GPS receiver  13 , and a microcontroller  15  for controlling the devices of the subsystem  10 . The radio module  12  and the GPS receiver  13  both comprise an interface  121 ,  131  for command input and data output. Similarly, the microcontroller  15  comprises an interface  151 A,  151 B for each device of the subsystem  10  for command output and data input. 
     The microcontroller  15  can be embedded or integrated in or connected to a terminal, for example. If the terminal is to use the radio module  12 , it can do so via the microcontroller  15  wherein applications for interfacing the radio module  12  are executed. The radio module  12  comprises a base band unit  123  that is adapted to execute applications for using the radio frequency part  125 . The base band unit  123  comprises an internal real time clock  256 . Then the necessary communication between the microcontroller  15  and the radio module  12 , in order to create a speech or data communication, for example, is carried out between the serial interface  151 A in the microcontroller  15  and the serial interface  121  in the radio module  12 . 
     For a satellite positioning functionality, a GPS receiver  13  is connected in a similar manner like the radio module  12 , via its serial interface  131  to the other serial interface  151 B of the microcontroller  15 . The GPS receiver  13  further comprises a radio frequency part  135  and a GPS base band unit  133 . 
     Traditionally, the local data interface of a GPS receiver complies with one of the NMEA standards. NMEA standards NMEA-0180, 0182 and 0183 define electrical interfaces and data protocols for communications between marine instrumentation, for example. These NMEA standards recommend that for a GPS receiver, the interface should comply with RS-232 or EIA-422. In practice, as a consequence, the data connection between a GPS receiver and a device communicating with the GPS receiver requires one data line only and can be carried out using one connector. 
     The interfaces through which the radio module  12  and of the GPS receiver  13  are controllable by the microcontroller  15  are serial interfaces. For communication, usually the standardized AT command language is used between the microcontroller  15  and the radio module  12 . The command language of the GPS receiver  13  is usually the NMEA protocol. 
     If the device using the system  100  comprising the subsystem  10  and microcontroller  15  needs to use both the radio module  12  and the GPS receiver  13 , it would, on its application level, need to process and synchronize data from and to both of these devices. Such a case is encountered, for example, when Assisted GPS is used where a cellular network sends synchronization information, using which the necessary synchronization of the GPS receiver  13  can be performed essentially faster. 
     The synchronization information is first received from the cellular network by the radio module  12  which then passes it either through the microcontroller  15  to an application running in the terminal or to an application running in the microcontroller  15 . The application then in turn passes this information to the GPS receiver  13  through the microcontroller  15 . 
     The synchronization information for a GPS receiver  13  comprises many different kinds of data to enable the GPS receiver  13  to start with the positioning. This information includes in addition to current visibility of satellites also the current date and time. For this reason a real time clock is necessary. A simple GPS receiver  13  nevertheless does not contain an internal real time clock, so the time information has to be available from the microcontroller  15 , e.g. from its internal real-time clock  156 . 
     BRIEF SUMMARY 
     Under the embodiments discussed below, the complexity of microcontroller design and the complexity of design of applications using a satellite positioning system receiver and a radio module are reduced. 
     By adapting a radio module to pass messages received via an external interface to the satellite positioning system receiver via an internal interface, and to receive messages from the satellite positioning system receiver via an internal interface, and to pass them further to the external interface, the microcontroller can be made simpler because the microcontroller does not need to have an additional interface for the satellite positioning system receiver. This may in turn reduce the complexity of programming devices using the satellite positioning system receiver and the radio module, such as terminals, since they may now use the same interface for sending and receiving messages to and from the satellite positioning system receiver as they use to communicate with the radio module. This is particularly advantageous when the radio module is adapted to work on AT commands (or AT-like commands) and further adapted to pass at least some of the commands in the AT-like command language to the satellite positioning system receiver. 
     By adapting the satellite positioning system receiver to use the same real time clock as the radio module, the design of the system can also be made easier since the synchronization of two clocks in these devices is not necessary. 
     Under an exemplary embodiment, a system includes a processing unit adapted to control both the radio module and the satellite positioning system receiver. Design of devices using the system, especially design of a microcontroller and of a terminal using said microcontroller, can be made easier since the number of processors in the system can be reduced. In this way, the controlling of the system or programming of applications can be made easier. Further, costs may be saved because the processing unit can overtake the function of the base band unit of the satellite positioning system receiver, and a separate base band unit can thus be omitted. Furthermore, the processing unit can be adapted to perform the functions necessary for network-assisted satellite positioning. In this manner, information how the network-assisted satellite positioning functionality works does not need to be disclosed to clients any more, because the satellite positioning system receiver does not need to be transparent any more since the functionality can wholly be implemented out in the system. 
     By adapting the processing unit to control the radio module with a first subset of commands received, and the satellite positioning system receiver with a second subset of commands received, the interfacing can also be made simpler, and even more so if commands in the first subset and in the second subset have a common format. As an example, NMEA commands may be mapped on AT commands. 
     If the processing unit is adapted to: i) synchronize the activation of the satellite positioning system receiver with that the radio module, or ii) synchronize setting of the satellite positioning system receiver to a standby state with setting of the radio module to a standby state, energy can be saved, especially if the satellite positioning system receiver is to be used as when network-assisted satellite positioning system receiver. For the network-assisted satellite positioning functionality, synchronization information should be received from a cellular network. Therefore, a connection to the network through the radio module is a prerequisite for using the satellite positioning system receiver with the network-assisted satellite positioning functionality. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The various objects, advantages and novel features of the present disclosure will be more readily apprehended from the following Detailed Description when read in conjunction with the enclosed drawings, in which: 
         FIG. 1  illustrates a conventional system comprising a radio module and a GPS receiver; 
         FIG. 2  illustrates an exemplary embodiment that includes a radio module coupled to a microcontroller via an external interface and the radio module communicates with a GPS via an internal interface; and 
         FIG. 3  illustrates another exemplary embodiment, where GPS receiver is directly controlled by a base band unit of the radio module disclosed in  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 2  shows an exemplary embodiment, where radio module  22  preferably comprises an internal interface  221 , through which it is connected to an internal interface  131  of the GPS receiver  23 . The internal interfaces  131 ,  221  are preferably serial interfaces. 
     The radio module  22  may receive data via interface  121  from the microcontroller  25  which passes it to the interface  121  via its interface  151 . Both interfaces  121 ,  151  are preferably serial interfaces. 
     The radio module  22  acts as master and controls the GPS receiver  23 . The controlling is performed in both terms of data and energy balance. This means that the radio module  22  can synchronize the GPS receiver  23  with its own energy saving behavior. 
     The program code executable in the base band unit  123  of the radio module  22  is capable of initializing the GPS receiver  23  to process data received from the GPS receiver  23  and to send necessary data to it. 
     Data from a microcontroller  25  to the GPS receiver  23  and from the GPS receiver  23  to the microcontroller  25  is communicated, preferably instead of using the NMEA format, reformulated and provided as AT commands. 
     Data, such as date and time, that can be used to synchronize the GPS receiver  23 , are received by the radio module  22  from the microcontroller  25 . Then they are extracted by the RTC  256  of the radio module  22 . The cycle frequency, with which the GPS receiver  23  may pass position data to the radio module  22 , is defined. Furthermore, the operation times of the GPS receiver  23  are synchronized to those of the radio module  22  in order to reduce the current consumption of the system  20 . 
     An Assisted GPS application executed in the radio module  22  sends to the GPS receiver  23  GPS assistance information that the radio module  22  has received from a cellular network. The GPS positioning results received by the radio module  22  from the GPS receiver  23  are first buffered and then transferred to the microcontroller  25 . Preferably, the GPS positioning results are given to the microcontroller  25  as an answer to an AT command. 
       FIG. 3  discloses another exemplary embodiment that modifies systems  20  and  200  shown in  FIG. 2 . 
     Under the embodiment, an interface is provided between radio module  32  and the GPS receiver  33 . The radio frequency part  135  of the GPS receiver  33  is now directly controlled by the base band unit  323  of the radio module  32 . Program code performing the functions of the program code of the GPS base band unit  133  is executed in the base band  323  of the radio module  32 . In this manner, there is no need for a separate GPS base band unit  133 . Furthermore, ROM and RAM of the GPS receiver  33  can be omitted. The Real Time Clock  156  of the microcontroller  156  may also be omitted. 
     The principles underlying the present disclosure can be used for systems comprising other kinds of radio modules than those for GSM. For example, radio modules for communication with a CDMA or WLAN network are also possible either alone or in combination with each other or GSM. 
     In the example above, the Global Positioning System (GPS) was used as an example of a satellite positioning system. The invention is nevertheless not limited to the GPS system but can be used with any other satellite positioning system instead of or in addition to the GPS system. The planned European Galileo navigation system is a further example of a suitable satellite positioning system. 
     Moreover, instead of using a GPS receiver, another satellite positioning system receiver can be used. Also, in the context of such another satellite positioning system, instead of or in addition to a network-assisted GPS functionality a network-assisted satellite positioning functionality can be used. 
     While the invention has been described with reference to one or more exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.