Unidirectional USB interface circuit

• US 7,840,742 B2
• Filed: 07/07/2008
• Issued: 11/23/2010
• Est. Priority Date: 07/06/2007
• Status: Active Grant

• Current Assignee: Election Systems & Software Incorporated
• Original Assignee: ES&S Automark, LLC
• Inventors: Holly, Paul, Berland, Kerry, Berland, Paul
• Primary Examiner(s): PHAN, RAYMOND NGAN
• Application Number:
  US12/168,672
• Publication Number:
  US 20090013111A1
• Time in Patent Office: 869 Days
• Field of Search: 710311-314, 710104-106, 710/110, 710 62- 64, 710 72- 73, 710/31
• US Class Current: 710/315
• CPC Class Codes: G06F 13/4027 using bus bridges G06F13/4022 takes precedence
• CPC Class Codes: G06F 2213/0042 Universal serial bus [USB]

Abstract

A circuit interfaced between a first USB host and a second USB host for providing unidirectional transmission of data signals from the first USB host to the second USB host is provided. A first converter circuit is operable to receive data signals from the first USB host and convert them from a USB protocol to a second communications protocol. A second converter circuit is operable to receive the converted data signals from the first converter circuit and convert them from the second communications protocol to the USB protocol for transmission to the second USB host. The first and second converter circuits are electrically connected to each other in such a manner as to provide a transmission path from the first USB host to the second USB host and to disable a transmission path from the second USB host to the first USB host.

Claims

1. A circuit interfaced between a first Universal Serial Bus (USB) host and a second USB host for providing unidirectional transmission of data signals from said first USB host to said second USB host, said circuit comprising:

a first circuit configured for electrical connection to said first USB host;

a second circuit configured for electrical connection to said second USB host; and

wherein said first and second circuits are electrically connected to each other in such a manner as to allow the transmission of data signals from the first USB host to the second USB host and prohibit the transmission of data signals from the second USB host to the first USB host.

2. The circuit of claim 1, wherein said first and second circuits are each operable to convert data signals between a USB protocol and a second communications protocol.

3. The circuit of claim 1, wherein said first circuit is operable to receive data signals from said first USB host and convert said data signals from a USB protocol to a second communications protocol, and wherein said second circuit is operable to receive said converted data signals from said first circuit and convert said converted data signals from said second communications protocol to said USB protocol for transmission to said second USB host.

4. The circuit of claim 1, wherein said first USB host is disposed on an election machine and said second USB host is disposed on a computing device.

5. The circuit of claim 1, wherein said first USB host and said first and second circuits are disposed on an election machine so as to provide a unidirectional USB port on said election machine.

6. The circuit of claim 1, wherein said first and second circuits are configured to detachably connect to a USB port of an election machine and a USB port of a computing device, respectively.

7. The circuit of claim 2, wherein said second communications protocol is selected from the following group:

RS-232, RS-422, RS-485, I²C, SPI and parallel I/O.

8. The circuit of claim 2, wherein said second communications protocol provides for bidirectional transmission of data signals over at least two physically separated transmission paths.

9. The circuit of claim 3, wherein:

said first circuit includes a first USB interface for electrical connection to said first USB host, said first circuit also including a first serial universal asynchronous receiver/transmitter (UART) interface having a receiver terminal and a transmitter terminal; and

said second circuit includes a second USB interface for electrical connection to said second USB host, said second circuit also including a second serial UART interface having a receiver terminal and a transmitter terminal.

10. The circuit of claim 4, wherein said first and second circuits are operable to transmit a plurality of files from said first USB host of said election machine to said second USB host of said computing device, said files selected from the following group:

bootloader files, operating system files, application files, and combinations thereof.

11. The circuit of claim 8, wherein said first and second circuits are configured such that one of said physically separated transmission paths is used for transmission of data signals from said first USB host to said second USB host and the other of said physically separated transmission paths is disabled so as to prevent transmission of data signals from said second USB host to said first USB host.

12. The circuit of claim 9, wherein said transmitter terminal of said first serial UART interface is electrically connected to said receiver terminal of said second serial UART interface so as to provide said transmission path from said first USB host to said second USB host, and wherein said transmitter terminal of said second serial UART interface is not connected to said receiver terminal of said first serial UART interface so as to disable said transmission path from said second USB host to said first USB host.

13. An election machine with a unidirectional Universal Serial Bus (USB) port, said election machine comprising:

a USB host for providing data signals in accordance with a USB protocol;

a first converter circuit electrically connected to said USB host and operable to receive said data signals from said USB host and convert said data signals from said USB protocol to a second communications protocol;

a second converter circuit electrically connected to said first converter circuit and operable to receive said converted data signals from said first converter circuit and convert said converted data signals from said second communications protocol to said USB protocol; and

wherein said first and second converter circuits are electrically connected to each other in such a manner as to allow the transmission of data signals from the first USB host to the second USB host and prohibit the transmission of data signals from the second USB host to the first USB host so as to provide a unidirectional USB port on said election machine.

14. The election machine of claim 13, wherein said second communications protocol is selected from the following group:

RS-232, RS-422, RS-485, I²C, SPI and parallel I/O.

15. The election machine of claim 13, wherein said second communications protocol provides for bidirectional transmission of data signals over at least two physically separated transmission paths.

16. The election machine of claim 13, wherein:

said first converter circuit includes a first USB interface electrically connected to said first USB host, said first converter circuit also including a first serial universal asynchronous receiver/transmitter (UART) interface having a receiver terminal and a transmitter terminal; and

said second converter circuit includes a second USB interface for electrical connection to a computing device, said second converter circuit also including a second serial UART interface having a receiver terminal and a transmitter terminal.

17. The election machine of claim 13, wherein a USB port of a computing device is detachably connected to said universal USB port of said election machine.

18. The election machine of claim 15, wherein said first and second converter circuits are configured such that one of said physically separated transmission paths comprises said transmission path from said first converter circuit to said second converter circuit and the other of said physically separated transmission paths comprises said disabled transmission path from said second converter circuit to said first converter circuit.

19. The election machine of claim 16, wherein said transmitter terminal of said first serial UART interface is electrically connected to said receiver terminal of said second serial UART interface so as to provide said transmission path from said first converter circuit to said second converter circuit, and wherein said transmitter terminal of said second serial UART interface is not connected to said receiver terminal of said first serial UART interface so as to disable said transmission path from said second converter circuit to said first converter circuit.

20. The election machine of claim 17, wherein said universal USB port of said election machine is operable to transmit a plurality of files from said election machine to said USB port of said computing device, said files selected from the following group:

bootloader files, operating system files, application files, and combinations thereof.

21. The election machine of claim 20, wherein said election machine further comprises an input device operable to receive a download command that initiates said transmission of said files from said election machine to said computing device.

22. The election machine of claim 21, wherein said input device comprises a touch screen display of said election machine.

23. A circuit interfaced between a first Universal Serial Bus (USB) host and a second USB host for providing unidirectional transmission of data signals from said first USB host to said second USB host, said circuit comprising:

a first converter circuit with a first USB interface for electrical connection with said first USB host and a first serial universal asynchronous receiver/transmitter (UART) interface having a receiver terminal and a transmitter terminal;

a second converter circuit with a second USB interface for electrical connection with said second USB host and a second serial UART interface having a receiver terminal and a transmitter terminal; and

wherein said transmitter terminal of said first serial UART interface is electrically connected to said receiver terminal of said second serial UART interface so as to allow the transmission of data signals from said first USB host to said second USB host, and wherein said transmitter terminal of said second serial UART interface is not connected to said receiver terminal of said first serial UART interface so as to prohibit the transmission of data signals from said second USB host to said first USB host.

24. The circuit of claim 23, wherein said first USB host is disposed on an election machine and said second USB host is disposed on a computing device.

25. The circuit of claim 23, wherein said first USB host and said first and second converter circuits are disposed on an election machine so as to provide a unidirectional USB port on said election machine.

26. The circuit of claim 23, wherein said first and second converter circuits are configured to detachably connect to a USB port of an election machine and a USB port of a computing device, respectively.

27. The circuit of claim 24, wherein said first and second converter circuits are operable to transmit a plurality of files from said first USB host of said election machine to said second USB host of said computing device, said files selected from the following group:

bootloader files, operating system files, application files, and combinations thereof.

28. A method of securely downloading files from an election machine to a computing device, said method comprising:

providing an election machine with a unidirectional Universal Serial Bus (USB) port;

providing a computing device with a USB port;

connecting said USB port of said computing device to said unidirectional USB port of said election machine; and

inputting a download command into said election machine so as to initiate said download of said files from said election machine to said computing device.

29. The method of claim 28, wherein said unidirectional USB port of said election machine comprises:

a USB host for providing data signals in accordance with a USB protocol;

a first converter circuit electrically connected to said USB host and operable to receive said data signals from said USB host and convert said data signals from said USB protocol to a second communications protocol;

a second converter circuit electrically connected to said first converter circuit and operable to receive said converted data signals from said first converter circuit and convert said converted data signals from said second communications protocol to said USB protocol; and

wherein said first and second converter circuits are electrically connected to each other in such a manner as to provide a transmission path from said first converter circuit to said second converter circuit and to disable a transmission path from said second converter circuit to said first converter circuit.

30. The method of claim 28, wherein said files are selected from the following group:

bootloader files, operating system files, application files, and combinations thereof.

31. The method of claim 28, wherein said election machine includes an input device for receiving said download command.

32. The method of claim 29, wherein said second communications protocol is selected from the following group:

RS-232, RS-422, RS-485, I²C, SPI and parallel I/O.

33. The method of claim 29, wherein:

said first converter circuit includes a first USB interface electrically connected to said first USB host, said first converter circuit also including a first serial universal asynchronous receiver/transmitter (UART) interface having a receiver terminal and a transmitter terminal; and

said second converter circuit includes a second USB interface for electrical connection to said computing device, said second converter circuit also including a second serial UART interface having a receiver terminal and a transmitter terminal.

34. The method of claim 31, wherein said input device comprises a touch screen display of said election machine.

35. The method of claim 33, wherein said transmitter terminal of said first serial UART interface is electrically connected to said receiver terminal of said second serial UART interface so as to provide said transmission path from said first converter circuit to said second converter circuit, and wherein said transmitter terminal of said second serial UART interface is not connected to said receiver terminal of said first serial UART interface so as to disable said transmission path from said second converter circuit to said first converter circuit.

36. A circuit interfaced between a first Universal Serial Bus (USB) host and a second USB host for providing unidirectional transmission of data signals from said first USB host to said second USB host, said circuit comprising:

first means for receiving data signals from said first USB host and converting said data signals from a USB protocol to a second communications protocol; and

second means for receiving said converted data signals from said first means and converting said converted data signals from said second communications protocol to said USB protocol for transmission to said second USB host and for prohibiting the transmission of data signals from said second USB host to said first USB host.

37. The circuit of claim 36, wherein said second communications protocol is selected from the following group:

RS-232, RS-422, RS-485, I²C, SPI and parallel I/O.

38. The circuit of claim 36, wherein said second communications protocol provides for bidirectional transmission of data signals over at least two physically separated transmission paths.

39. The circuit of claim 36, wherein said first USB host is disposed on an election machine and said second USB host is disposed on a computing device.

40. The circuit of claim 36, wherein said first USB host and said first and second means are disposed on an election machine so as to provide a unidirectional USB port on said election machine.

41. The circuit of claim 36, wherein said first and second means are configured to detachably connect to a USB port of an election machine and a USB port of a computing device, respectively.

42. The circuit of claim 38, wherein said first and second means are configured such that one of said physically separated transmission paths is used for transmission of data signals from said first USB host to said second USB host and the other of said physically separated transmission paths is disabled so as to prevent transmission of data signals from said second USB host to said first USB host.

43. The circuit of claim 39, wherein said first and second means are operable to transmit a plurality of files from said first USB host of said election machine to said second USB host of said computing device, said files selected from the following group:

bootloader files, operating system files, application files, and combinations thereof.