Abstract:
A tool for programming integrated circuits which reduces redundancy of parts by making different and multiple programmable integrated circuit sockets of particular sizes and shapes adaptable to more than one programming cable, and therefore many different integrated circuits. By inserting a small interconnect adapter board onto the main programming board, it rewires the main board such that one or more of the included device programming sockets is connected properly to the correct in-system cable connector required by the manufacturer of the particular integrated circuit being programmed. Since the integrated circuit sockets are not permanently wired to a particular programming cable connector, the programming adapter is extremely versatile.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     This invention pertains to the field of electrical engineering. The invention is a circuit board containing multiple sockets and multiple programming cable connectors, and an adapter for wiring these sockets to a particular configuration. It is a tool for programming integrated circuits, primarily intended for programming complex programmable logic devices from many manufacturers, but can also be used to program microprocessors and memory. This invention reduces redundancy of parts by making different integrated circuit sockets adaptable to more than one programming cable, and therefore many different integrated circuits.  
         [0002]     Usually, programming boards are provided by the manufacturer at a substantial cost. For example, one board usually connects a single model integrated circuit, with its necessary connections permanently wired to an integrated circuit socket, and to a single in-system programming cable, and the manufacturer may have dozens of different programming boards. To program many different types of integrated circuits, one would normally have to buy many programming boards from the manufacturer. The integrated circuit sockets used to program these integrated circuits are of different shapes and pin counts, and of several styles, such as the open-top style, in which spring-loaded conductors make a small contact on the end of a surface-mounted device, or the clamshell style, in which a hinged cover holds in place an integrated circuit resting on conductive metal strips, or of the zero insertion force style.  
         [0003]     Each manufacturer has different programmable integrated circuits that can be programmed with the same cable. There may be several different integrated circuits of the same size and shape (Joint Electron Device Engineering Council or JEDEC configuration), although the numbering (position) of the supply voltage, ground, and programmability pins may be different. These integrated circuits of the same JEDEC configuration may be made by the same or different manufacturers.  
         [0004]     Several integrated circuits from the same manufacturer, all of which have the same JEDEC configuration, may have different pin arrangements. Conversely, several integrated circuits from different manufacturers may all have a common JEDEC configuration, but many or all must be programmed using different cables.  
         [0005]     This invention is primarily an attempt to create a universal adapter which allows for both programming complex programmable logic devices (CPLDs) from different manufacturers before placing and soldering these devices on their final printed circuit boards, and for the capability to quickly move the design to an integrated circuit from another manufacturer before the final circuit board is designed.  
       BRIEF SUMMARY OF THE INVENTION  
       [0006]     This invention is a tool for programming integrated circuits which reduces redundancy of parts by making different and multiple programmable integrated circuit sockets of particular sizes and shapes adaptable to more than one programming cable, and therefore many different integrated circuits. By inserting a small interconnect adapter board onto the programming board, it allows several integrated circuits which are from the same manufacturer, all of which have the same JEDEC configuration but have different pin arrangements, to be programmed on the same board. It also allows several integrated circuits from different manufacturers that all have a common JEDEC configuration, but must be programmed using different in-system programming cables to be programmed on the same board. Lastly, it allows integrated circuits of more than one JEDEC configuration to be programmed with the same in-system programming cables on the same board. It is intended to be a universal platform for programming surface-mount and through-hole CPLDs which are not yet soldered to their final circuit boards. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]     The drawings illustrate one possible method of implementing the invention.  
         [0008]      FIG. 1  is a plan view of the circuit board used to program the target integrated circuits.  
         [0009]      FIG. 2  is a perspective view of the adapter circuit board used for one possible interconnection scheme.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0010]     With regard to  FIG. 1 , a printed circuit board for the programming of programmable integrated circuits, such as microprocessors and complex programmable logic devices is disclosed.  
         [0011]     Terminal blocks  1 ,  2 , and  3  are used for connection of direct current (DC) power supply wiring. Capacitors  4 ,  5 , and  6  stabilize the input voltages, which are then connected via circuit board traces to voltage regulators  7 ,  8 , and  9 . Each of the voltage regulators provides a separate commonplace device operating voltage, such as 5.0 volts DC for regulator  7 , 3.3 volts DC for regulator  8 , and 2.5 volts DC for regulator  9 . In the actual commercial implementation there may be more terminal blocks and separate voltages. The input voltage levels connected to terminal blocks  1 ,  2 , and  3  depend on the input specifications for regulators  7 ,  8 , and  9 , respectively. The output voltages of regulators  7 ,  8 , and  9 , are stabilized by capacitors  10 ,  11 , and  12 , respectively. These stabilized output voltages are connected via conductive circuit board traces to separate pin receptacles  19  of the zero-insertion force (ZIF) socket  18 .  
         [0012]     One of the many conductive circuit board traces  13  is noted. Lines of similar width in the drawing are also conductive circuit traces. The path of a conductive circuit trace  14  running beneath a component is depicted using double dotted lines.  
         [0013]     An in-system programming connector  15  of the “shrouded header” variety, has all of its conductive pins  16  connected via circuit board traces to separate pin receptacles  19  of the ZIF socket  18 . Connector  15  mates an in-system programming cable, available from the manufacturer of the particular programmable integrated circuit contained in one of the target sockets  21 ,  26  or  28 . These in-system programming (ISP) cables connect to a computer for the purpose of transferring information to an integrated circuit.  
         [0014]     Likewise, another in-system programming connector  17  of the plain “header” variety and of another wiring configuration and/or compatible with another brand or model of integrated circuit also has all of its conductive pins connected via circuit board traces to separate pin receptacles  19  of the ZIF socket  18 .  
         [0015]     A socket  18  of the ZIF variety is used to hold and connect into the circuit the secondary interconnection circuit board shown in  FIG. 2 . The ZIF socket contains an array of receptacles  19  which accept the pins contained on the interconnection circuit board  31  of  FIG. 2 . The ZIF socket is customarily used for connecting an integrated circuit of the pin grid array (PGA) type to a circuit board. In this invention, it is used to connect a small circuit board to the main circuit board. The ZIF socket is operated by raising the lever  20 , which loosens the internal contacts to prevent damage to the pins of the device to which it connects, and then placing the interconnection circuit board  31  into the socket, and then lowering the lever, which holds the device firmly in place and makes reliable electrical contact between all of the mating device pins and socket receptacles  19 .  
         [0016]     A socket  21  of the clamshell variety, with hinged lid, is used to accommodate a programmable integrated circuit of the surface-mount “quad flatpack” style. All conductors of clamshell socket  21  are connected via circuit board traces to separate pin receptacles  19  of the ZIF socket  18 . The integrated circuit&#39;s leads rest on conductive contacts  23 . The socket is operated by placing the integrated circuit on the conductive contacts  23  and then closing the lid  25  which pivots on hinge  24  and is held in place by latch  22 . During programming the socket remains closed.  
         [0017]     A socket  26  of the open-top variety is used to accommodate another size programmable integrated circuit of the surface-mount “quad flatpack” style. All conductors of open-top socket  26  are connected via circuit board traces to separate pin receptacles  19  of the ZIF socket  18 . The integrated circuit&#39;s leads are clamped under spring-loaded conductive contacts  27 . The socket is operated by holding down the spring-loaded rim of socket  26 , which raises slightly the spring-loaded conductive contacts  27 , then placing the integrated circuit under the spring-loaded conductive contacts  27  and then releasing the rim until programming is complete.  
         [0018]     A socket  28  of the ZIF variety is used to accommodate another size programmable integrated circuit of the dual inline package style. It has conductive receptacles  29  to accept the integrated circuit pins, and is operated in a similar fashion as ZIF socket  18 .  
         [0019]      FIG. 1  has shown one implementation of the invention. Other implementations may be made in which in-system programming connectors  15  and  16  have different numbers of pins, or different style connectors to mate with a particular manufacturer&#39;s in-system programming cable, or there may be more than two in-system programming connectors. Additionally, integrated circuit sockets  21 ,  26 , and  28  which are used for connecting the target programmable devices into the circuit may have different numbers of pins, and/or one or more of the sockets may accommodate a different integrated circuit package style, and there may be any number (one or greater) of integrated circuit sockets for connecting the target programmable devices. The ZIF socket  18  typically has in excess of 300 pins, which makes possible wiring the pins of the target programmable integrated circuits (by means of their sockets and the adapter circuit board of  FIG. 2 ) to the proper supply voltages and programming cable configuration.  
         [0020]      FIG. 2  shows a perspective view of one possible interconnection adapter  31 . This adapter  31  is a small printed circuit board and mates with ZIF socket  18 , and has conductive circuit board traces  34  on its top layer and conductive circuit board traces  37  on its bottom layer. Lines of similar width as  34  also depict conductive circuit traces. Conductor pins  32  as shown from the top and  38  as shown from the underside of adapter  31  are soldered to the printed circuit board. Dots of similar style as  32  and posts of similar style as  38  show other interconnection pins. Conductor pins  33 , while not connected to any circuits, serve to align the adapter such that it is oriented properly into ZIF socket  18 . Text label  35  shows the purpose of the interconnection adapter  31 , such as model number of target programmable device, in-system programming cable type, and target socket style and pin count. Text label  36  shows the model number of the interconnection adapter  31 . In the implementation shown, when adapter  31  is mated with ZIF socket  18 , in-system programming cable  17  becomes wired to the surface-mount integrated circuit connected in open-top socket  26  and a 3.3 volt DC supply is used.  
         [0021]     Other implementations of adapter  31  in  FIG. 2  may have the adapter wired to any other possible combination of supply voltage, in-system programming cable, and target device socket or sockets, and this other possible combination may match the implementation shown in  FIG. 1  or it may match another conceivable implementation.