Abstract:
A method of programming one or more relay based electrical devices comprises the steps of selecting an electrical device to program, switching the relay from a first state to a second state, and applying a time varying signal to the relay associated with the selected device. The method also includes the steps of counting signal transitions occurring during the switching of the relay, and comparing the counted signal transitions to a predetermined value. The method further includes the step of programming the device based on the comparison step. Accordingly, the programming methodology advantageously enables programming of the device by employing the switching time period of the relay which allows for elimination of a separate dedicated programming terminal.

Description:
TECHNICAL FIELD 
     The present invention generally relates to relay based electrical devices and, more particularly, to a method of programming relay based devices, such as electrical connectors for use in automotive vehicles. 
     BACKGROUND OF THE INVENTION 
     Automotive vehicles commonly employ a series of electrical connectors for connecting power to various high current electrical devices, such as headlamps, solenoids, motors, and other electrically operated devices. High current electrical connectors, such as those drawing 5 amps or greater, typically employ a relay that turns on and off the electrical device connected thereto in response to control signals. Each electrical connector generally has limited signal processing capability so that it may perform a designated switching operation pursuant to the externally generated control signal. Relay based electrical connectors are widely known and are commonly used in automotive vehicles. 
     Conventional electrical connectors generally employ a pair of load terminals, e.g., contact pins, for electrically connecting the connector to a designated load device. One of the terminals provides a feed forward current path, while the other terminal provides a feed back current path. In addition, conventional relay based electrical connectors typically employ a third terminal, which is a dedicated programming terminal, that enables the electrical connector to be programmed during or following the manufacture of the connector. Examples of programmed data typically include address, function, and calibration information. The programming operation is generally performed at the manufacturing site where a header, a series of wires, and a series of the connectors to be programmed are connected together. The dedicated programming terminal of each electrical connector is generally connected to a programming rig that provides a signal to the connector to initiate the programming of that particular connector. Once the programming operation is complete, the dedicated programming terminal generally is no longer employed, and thereafter remains unused. 
     As a consequence, the aforementioned conventional relay based connectors require three separate electrical terminals, including the dedicated programming terminal which is generally not employed during the operation of the device. The dedicated programming terminal adds to the overall cost, size, and complexity of the connector. As a result, it is therefore desirably to provide for a programmable relay based connector that employs a minimal number of electrical terminals. 
     SUMMARY OF THE INVENTION 
     In accordance of the teachings of the present invention, a method of programming one or more relay based electrical devices, such as electrical connectors, is provided. The method comprises the steps of selecting an electrical device to program, switching the relay associated with the selected electrical device from a first state to a second state, and applying a time varying signal to the relay associated with the selected device. The method also includes the steps of counting signal transitions occurring during the switching of the relay, and comparing the counted signal transitions to a predetermined value. The method further includes the step of programming the device based on the comparison step. Accordingly, the programming methodology advantageously enables programming of the device by utilizing the relay switching which allows for elimination of a separate dedicated programming terminal. 
     These, and additional objects, advantages, features and benefits of the present invention will become apparent from the following specification. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will now be described, by way of example, with reference to the accompanying drawings, in which: 
     FIG. 1 is a block diagram illustrating the programming of a plurality of relay based electrical connectors according to the present invention; 
     FIG. 2 is a block circuit diagram further illustrating the programming of one relay based connector; 
     FIG. 3 illustrates signal transitions counted by a counter during relay switching from ground to battery during the programming operation; 
     FIG. 4 is a flow diagram illustrating the methodology of programming the relay based electrical connector; and 
     FIG. 5 is a block diagram illustrating use of programmed relay based electrical connectors in a vehicle. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, a plurality of electrical connectors  10 A- 10 N are shown interconnected to each other via three wires which provide for a battery line  12 , a ground line  14 , and a serial data bus line  16 . Electrical connectors  10 A- 10 N may be electrically coupled to each of lines  12 ,  14 , and  16  via conventional insulation displacement connections. The series of interconnected connectors may include any number of connectors. Each of electrical connectors  10 A- 10 N has a relay for energizing or de-energizing a load device that may be connected thereto. Load devices may include headlamps, motors, and various other electrically operated devices. Each of the connectors  10 A- 10 N further includes a pair of electrical terminals T 1  and T 2 , such as male or female receptacles, which provide for the interfaced connection to the corresponding load device. One of the terminals T 1  and T 2  provides a feed forward current path, while the other of terminals T 1  and T 2  provides a feed back current path to complete the circuit path. 
     In addition, the series of interconnected electrical connectors  10 A- 10 N are coupled to a header connector  18 . The header connector  18  provides an interface that serves to allow for connection to external devices. During the programming operation, the header connector  18  is connected to a harness programmer  20 . Harness programmer  20  is a programming device that is used to program each of the electrical connectors  10 A- 10 N as described herein. Harness programmer  20  preferably includes a microprocessor  22 , memory  24 , and a waveform generator  26 . Waveform generator  26  supplies a time varying signal such as a square wave signal for example. Also included in harness programmer  20  is a switch  28  for switching amongst one of a plurality of contact positions A-N. Switch  28  selects one of the electrical connectors at a time to be programmed. Contact A is shown connected to electrical terminal T 1  of connector  10 A, contact B is shown connected to electrical terminal T 1  of contact  10 B, etc. The harness programmer  20  performs the programming operation, preferably at the manufacturing site, prior to installing the electrical connectors  10 A- 10 N in a vehicle. To program the electrical connectors  10 A- 10 N, the harness programmer  20  selects one of the electrical connectors  10 A- 10 N at a time, and applies the time varying signal to one of terminals T 1  and T 2  of the selected electrical connector as described herein. 
     With particular reference to FIG. 2, one electrical connector  10 A is further shown in greater detail. Electrical connector  10 A is equipped with a relay  30  which generally includes a relay coil  32  and a contact switch  34  for switching between ground and battery. One end of relay coil  32  is coupled to the battery input which may provide a DC voltage potential of twelve volts, for example. The fixed end of switch  34  is connected to terminal T 1  which is further shown connected to the external harness programmer  20 . Connector  10 A also includes a voltage divider made up of resistors  48 ,  50 , and  52 , which divides the voltage applied at terminal T 1  to a reduced voltage potential at the input of a counter  46 . 
     The electrical connector  10 A further includes an application specific integrated circuit (ASIC)  44  which has an NPN transistor  36 . Transistor  36  has a collector terminal coupled to one end of relay coil  32  opposite the battery terminal, and an emitter terminal coupled to ground. Transistor  36  also has a base connected to receive a relay control signal from a state machine  38 . In addition, ASIC  44  includes a serial bus decoder  40 , electrically programmable read only memory (EPROM)  42 , and counter  46 . Serial bus decoder  40  receives program message inputs via line  54  from harness programmer  20 . Program messages may include the information to be programmed such as address, function, and calibration information. The serial bus decoder  40  decodes the information received and provides the decoded data to the electronically programmable read only memory (EPROM)  42 . Counter  46  counts the number of signal pulse transitions received at its input from terminal T 1  and provides a count number to state machine  38 . State machine  38  is programmed to carry out a method of programming the electrical connector  10 A which includes counting the number of counts from counter  46  and actuating memory programming by burning the data received by decoder  40  into EPROM  42  in accordance with the programming method of the present invention. 
     The programming method of the present invention advantageously utilizes the switching of the relay  30  to enable programming of selected electrical connectors. By applying a time varying signal to one of the terminals, such as terminal T 1 , during the relay switching in which the relay switch  34  moves from one state, such as ground, to a second state, such as the battery potential, counter  46  is able to count the number of signal transitions provided during the relay switching transition to detect the application of the time varying signal which indicates that the electrical connector is selected for programming. 
     Referring to FIG. 3, one example of the detection of the time varying signal by counter  46  is illustrated during the relay switching operation. The time varying signal provides a series of voltage pulses  56 , such as the square wave signal shown, or other time varying signal. According to the example shown, the waveform generator supplies a 10 kHz square wave signal that varies between 0 and 12 volts. The 12 volts signal is converted to 5 volts via the voltage divider provided by resistors  48 ,  50 , and  52 . According to this example, a relay referred to as Model NEC ET 2-B3G1S, which is commercially available from NEC Corporation, was employed which has a switching time period of approximately 0.8 milliseconds to switch from the ground state to the battery potential state. During the switching period, the counter detects the 10 kHz signal and counts the signal pulse transitions. 
     Referring to FIG. 4, a method  60  of programming one or more electrical connectors is illustrated therein in accordance with the present invention. Method  60  begins with step  62  to power up the harness programmer as well as the series of relay based electrical connectors. In decision block  64 , method  60  checks to see if the selected connector is already programmed and, if so, jumps to a ready for a normal operation state  86 . If the selected connector has not yet been programmed, method  60  proceeds to decision block  66  to check if a new message has been received. If a new message has not been received, method  60  continues to check for the new message. Once a new message has been received, method  60  proceeds to decision block  68  to check if the received message is a program message and, if not, returns to decision block  66  to wait for a new message. 
     If the received message is a program message, methodology  60  proceeds to step  70  to clear the counter by setting count value N equal to zero. Thereafter, step  72  turns the relay associated with the selected electrical connector to the “on” state. The relay is turned on by switching the collector of transistor  36  to ground which causes switch  34  to transition from the ground state to the battery potential state. The transition of switch  34  between ground and battery typically undergoes a slight delay such as 2.2 milliseconds before leaving the grounded contact, and thereafter takes approximately 0.8 millisecond to reach the battery contact. The 0.8 millisecond time period lapsing between the switching states is utilized to count signal transitions applied at terminal T 1 . With the relay on, methodology  60  waits approximately 10 milliseconds in step  74  and then proceeds to read the count value N in step  76 . Once the count value N has been read, methodology  60  proceeds to turn off the relay in step  78 , and proceeds to decision block  80  to check if the count value N is greater than or equal to a minimal count value N min . If count value N does not exceed the minimum value N min  methodology  60  returns to decision block  66  to wait for a new message. If count value N is greater than or equal to the minimum required value N min , methodology  60  proceeds to step  82  to enable programming by burning the data in the EPROM  42 . In step  84 , method  60  set a programmed flag indicative of completion of the programming operation, and then returns to the ready for normal operation state  86 . 
     Once the electrical connectors have been programmed, the electrical connectors may be employed in a vehicle, according to one application. The programmed electrical connectors can be installed in a vehicle as shown in FIG. 5, according to one example. In FIG. 5, each of connectors  10 A- 10 N is connected to a load device such as respective load devices  88 A- 88 N. Load devices  88 A- 88 N may include lights, such as vehicle headlamps, and other devices that turn on and off in response to control signals. In addition, a controller  90  is shown connected to header connector  18 . Controller  90  has a microprocessor  92 , memory  94 , a first bus interface  96 , and a second bus interface  98 . The first bus interface  96  provides an interface between a vehicle data communication bus and controller  90 , while the second bus interface provides an interface between controller  90  and header connector  18 . The controller  90  is preferably employed to control operation of the programmed electrical connectors to turn the specific load devices  88 A- 88 N on and off, as desired. 
     Accordingly, the method of programming electrical devices, such as connectors, according to the present invention advantageously provides for a reduced complexity and low cost programming technique, which eliminates the need for separate dedicated programming terminals. By employing the present programming methodology, one of the feed forward and feed back terminals used to supply current to and from a load device may also be employed to select an electrical connector to enable programming thereof in accordance with the present invention. 
     To those skilled in the art to which this invention appertains, the above-described preferred embodiments may be subject to change or modification. Such change or modification can be carried out without departing from the scope of the invention, which is intended to be limited only by the scope of the appended claims.