Data transfer control device, electronic instrument, and data transfer control method

• US 20050201305A1
• Filed: 03/08/2005
• Published: 09/15/2005
• Est. Priority Date: 03/09/2004
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Shibata, Yukinari, Hasegawa, Tomonaga
• Granted Patent: US 7,706,309 B2
• Time in Patent Office: Days
• US Class Current: 370/282
• CPC Class Codes: H04L 25/0274 Arrangements for ensuring balanced coupling
• CPC Class Codes: H04L 25/0284 Arrangements to ensure DC-balance
• CPC Class Codes: H04L 25/0296 Arrangements to ensure DC-balance
• CPC Class Codes: H04L 25/4908 using mBnB codes
• CPC Class Codes: H04L 5/1438 Negotiation of transmission parameters prior to communication modified according to link quality H04L1/0001
• CPC Class Codes: H04L 5/16 Half-duplex systems; Simplex/duplex switching; Transmission of break signals non-automatically inverting the direction of transmission
• CPC Class Codes: H04L 5/18 Automatic changing of the traffic direction

Abstract

A data transfer control device includes: a transmitter circuit; a receiver circuit; a transfer direction switch circuit which performs switching a transfer direction; a transfer direction switch indication circuit which indicates the transfer direction switch circuit to switch the transfer direction; and a code generation circuit which generates a transfer direction switch request code when a transfer direction switch request has been received from an upper layer circuit. When the transfer direction switch request has been received from the upper layer circuit, the transmitter circuit transmits the transfer direction switch request code through a serial signal line, and the transfer direction switch indication circuit indicates the transfer direction switch circuit to switch from a transmission direction to a reception direction after the transfer direction switch request code has been transmitted.

Claims

1. A data transfer control device for performing data transfer through a serial signal line, the data transfer control device comprising:

a transmitter circuit which transmits data through a serial signal line;

a receiver circuit which receives data through a serial signal line;

a transfer direction switch circuit which performs switching between a transmission direction and a reception direction, the transmission direction being a transfer direction in which data is transmitted by the transmitter circuit, and the reception direction being a transfer direction in which data is received by the receiver circuit;

a transfer direction switch indication circuit which indicates the transfer direction switch circuit to switch the transfer direction; and

a code generation circuit which generates a transfer direction switch request code when a transfer direction switch request has been received from an upper layer circuit,

wherein, when the transfer direction switch request has been received from the upper layer circuit, the transmitter circuit transmits the transfer direction switch request code generated by the code generation circuit to a partner-side data transfer control device through the serial signal line, and the transfer direction switch indication circuit indicates the transfer direction switch circuit to switch the transfer direction from the transmission direction to the reception direction after the transfer direction switch request code has been transmitted.

2. The data transfer control device as defined in claim 1, comprising:

an encoder circuit which encodes data by using an encoding method which expands N bits of data to M bits (N<

M;

N and M are integers larger than one) of data; and

a parallel/serial conversion circuit which converts parallel data received from the encoder circuit to serial data and outputs the serial data to the transmitter circuit,

wherein the code generation circuit generates the transfer direction switch request code by generating a special code assigned to the transfer direction switch request code among special codes defined by the encoding method.

3. The data transfer control device as defined in claim 2,

wherein the code generation circuit receives a special code generation direction signal from the upper layer circuit, and generates the transfer direction switch request code when generation of the transfer direction switch request code has been directed by the special code generation direction signal.

4. The data transfer control device as defined in claim 1,

wherein the transmitter circuit transmits the transfer direction switch request code through the serial signal line in addition to data transmitted through the serial signal line.

5. The data transfer control device as defined in claim 4,

wherein the transmitter circuit outputs an idle signal, logical level of which is continuously fixed at a first logical level in units of a given number of bits or more to the serial signal line after transmitting the transfer direction switch request code through the serial signal line.

6. The data transfer control device as defined in claim 1, comprising:

a link controller as the upper layer circuit,

wherein, when a response packet has not been received from the partner-side data transfer control device after transmission of the transmitter circuit has been completed and a predetermined period of time has elapsed and a timeout has occurred, the link controller issues a transfer direction switch request which causes the transfer direction to be reversed from the reception direction to the transmission direction.

7. The data transfer control device as defined in claim 1, comprising:

a link controller as the upper layer circuit,

wherein, upon receiving a packet informing a CRC error from the partner-side data transfer control device after completion of transmission of the transmitter circuit, the link controller issues a transfer direction switch request which causes the transfer direction to be reversed from the reception direction to the transmission direction.

12. An electronic instrument, comprising:

the data transfer control device as defined in claim 1;

and

at least one of a communication device, a processor, an imaging device, and a display device.

13. An electronic instrument, comprising:

the data transfer control device as defined in claim 2;

and

at least one of a communication device, a processor, an imaging device, and a display device.

14. An electronic instrument, comprising:

the data transfer control device as defined in claim 4;

and

at least one of a communication device, a processor, an imaging device, and a display device.

15. An electronic instrument, comprising:

the data transfer control device as defined in claim 6;

and

at least one of a communication device, a processor, an imaging device, and a display device.

8. A data transfer control device for performing data transfer through a serial signal line, the data transfer control device comprising:

a transmitter circuit which transmits data through a serial signal line;

a receiver circuit which receives data through a serial signal line;

a transfer direction switch circuit which performs switching between a transmission direction and a reception direction, the transmission direction being a transfer direction in which data is transmitted by the transmitter circuit, and the reception direction being a transfer direction in which data is received by the receiver circuit;

a transfer direction switch indication circuit which indicates the transfer direction switch circuit to switch the transfer direction;

a code detection circuit which detects a transfer direction switch request code received by the receiver circuit; and

a notification signal generation circuit which generates a notification signal and outputs the generated notification signal to an upper layer circuit,

wherein, when the transfer direction switch request code has been detected by the code detection circuit, the transfer direction switch indication circuit indicates the transfer direction switch circuit to switch the transfer direction from the reception direction to the transmission direction, and the notification signal generation circuit generates a signal informing that a transfer direction switch request has been received from a partner-side data transfer control device and outputs the generated signal to the upper layer circuit.

9. The data transfer control device as defined in claim 8, comprising:

a serial/parallel conversion circuit which converts serial data received from the receiver circuit to parallel data; and

a decoder circuit which receives the parallel data from the serial/parallel conversion circuit and performs decode processing of data and a special code encoded by using a predetermined encoding method,

wherein the code detection circuit detects the transfer direction switch request code by detecting a special code assigned to the transfer direction switch request code among special codes defined by the encoding method.

10. The data transfer control device as defined in claim 8,

wherein, when a reception error has been detected at the time of or before detection of the transfer direction switch request code by the code detection circuit, the transfer direction switch indication circuit cancels switch indication of the transfer direction from the reception direction to the transmission direction.

11. The data transfer control device as defined in claim 8, comprising:

a link controller as the upper layer circuit,

wherein, when a CRC error of a packet received from the partner-side data transfer control device has been detected, the link controller transmits a packet for informing the CRC error to the partner-side data transfer control device, and issues a transfer direction switch request which causes the transfer direction to be reversed from the transmission direction to the reception direction after completion of transmission of the packet.

16. An electronic instrument, comprising:

the data transfer control device as defined in claim 8;

and

at least one of a communication device, a processor, an imaging device, and a display device.

17. An electronic instrument, comprising:

the data transfer control device as defined in claim 9;

and

at least one of a communication device, a processor, an imaging device, and a display device.

18. A data transfer control method for controlling data transfer between first and second data transfer control devices connected through a serial signal line, each of first and second data transfer control devices including:

a transmitter circuit which transmits data by current-driving a serial signal line;

a receiver circuit which receives data by detecting current flowing through a serial signal line; and

a transfer direction switch circuit which performs switching between a transmission direction and a reception direction, the transmission direction being a transfer direction in which data is transmitted by the transmitter circuit, and the reception direction being a transfer direction in which data is received by the receiver circuit;

the method comprising;

causing the transfer direction switch circuit of the first data transfer control device to switch the transfer direction from the transmission direction to the reception direction; and

causing the transfer direction switch circuit of the second data transfer control device to switch the transfer direction from the reception direction to the transmission direction after the transfer direction of the first data transfer control device has been switched from the transmission direction to the reception direction.

19. The data transfer control method as defined in claim 18, comprising:

canceling switching of the transfer direction of the second data transfer control device from the reception direction to the transmission direction when a reception error has occurred.

20. The data transfer control method as defined in claim 19, comprising:

canceling switching of the transfer direction of the second data transfer control device from the reception direction to the transmission direction when the reception error has occurred at the time of or before detection of a transfer direction switch request from the first data transfer control device to the second data transfer control device.