# Patent

## Title
Serial peripheral interface and method for data transmission

## Abstract

A serial peripheral interface of an integrated circuit includes: a first transfer pin for receiving an instruction and an address; and a clock pin for inputting a plurality of timing pulses each having a rising edge and a falling edge. After the first transfer pin receives the instruction, the integrated circuit receives the address through the first transfer pin in continuity with the receipt of the instruction. The first transfer pin receives the instruction at either of the rising edges and the falling edges of the timing pulses and receives the address at both of the rising edges and falling edges of the timing pulses.

## Background
This application is a continuation application of U.S. application Ser. No. 13/687,586, filed Nov. 28, 2012, which is a continuation application of U.S. application Ser. No. 13/362,801, filed Jan. 31, 2012, now U.S. Pat. No. 8,341,324, which is a continuation application of U.S. application Ser. No. 12/851,156, filed Aug. 5, 2010, now U.S. Pat. No. 8,135,896, which is a continuation application of U.S. application Ser. No. 11/896,846 filed Sep. 6, 2007, now U.S. Pat. No. 7,788,438. These related applications are incorporated herein by reference.


BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates in general to a serial peripheral interface and a data transmitting method thereof, and more particularly to a serial peripheral interface having a better overall behavior and a data transmitting method thereof.
Description of the Related Art
FIG. 1 (Prior Art) is a block diagram showing a conventional data transmission system. Referring to FIG. 1, the data transmission system 100 includes an integrated circuit 110 and a serial peripheral interface 120. The serial peripheral interface 120 has many pins, for example, including an input pin 122, an output pin 124, a chip select pin 126 and a clock pin 128. The input pin 122 receives a piece of serial data, including instructions and addresses, and transmits the piece of serial data to the integrated circuit 110. The output pin 124 reads a piece of serial data, including dummy cycles and multiple read out data, from the integrated circuit 110 and outputs the piece of serial data. The chip select pin 126 provides a chip select signal CS, and the clock pin 128 provides a clock signal SCLK.
FIG. 2 (Prior Art) shows timings for reading serial data in the conventional data transmission system. As shown in FIG. 2, for example, the piece of serial data includes an 8-bit instruction, a 24-bit address, n dummy cycles and multiple 8-bit read out data, wherein n is an integer greater than or equal to 0 and is not particularly limited. It can be determined according to the design of data transmission system 100. As shown in FIG. 2, when the chip select signal CS is low, the clock signal SCLK has many timing pulses. At this time, the input pin first receives the 8-bit instruction, and then receives the 24-bit address, which is the initial address of the data to be read. Then, n dummy cycles are provided for buffering. Next, the output pin reads and outputs the multiple 8-bit read out data.
The data transmission system 100 utilizes one single input pin and one single output pin of the serial peripheral interface 120 to perform the serial data transmitting operation. Consequently, only one bit of data is transmitted in one timing pulse, and the efficiency is not high. So, the overall behavior of the data transmission system 100 cannot be optimized.
SUMMARY OF THE INVENTION
The invention is directed to a serial peripheral interface and a data transmitting method thereof, in which many control pins of the serial peripheral interface are utilized to achieve a serial data transmission through multiple input pins and multiple output pins, and enhance the overall behavior of data transmission.
According to an embodiment of the present invention, a serial peripheral interface of an integrated circuit is provided. The serial peripheral interface includes a first transfer pin for receiving an instruction and an address; and a clock pin for inputting a plurality of timing pulses each having a rising edge and a falling edge. After the first transfer pin receives the instruction, the integrated circuit receives the address through the first transfer pin in continuity with the receipt of the instruction. The first transfer pin receives the instruction at either of the rising edges and the falling edges of the timing pulses and receives the address at both of the rising edges and falling edges of the timing pulses.
According to another embodiment of the present invention, a data transmitting method applied to a serial peripheral interface of an integrated circuit is provided. The serial peripheral interface includes a plurality of pins and a clock pin. The method includes inputting a plurality of timing pulses by the clock pin; and receiving an instruction and receives an address by a first transfer pin of the plurality of pins, wherein the instruction is received at either of rising edges and falling edges of the timing pulses and the address is received at both of the rising edges or the falling edges of the timing pulses.
The invention will become apparent from the following detailed description of the preferred but non-limiting embodiments. The following description is made with reference to the accompanying drawings.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 (Prior Art) is a block diagram showing a conventional data transmission system.
FIG. 2 (Prior Art) shows timings for reading serial data in the conventional data transmission system.
FIG. 3 is a block diagram showing an example of a data transmission system according to a preferred embodiment of the invention.
FIG. 4A shows timings of serial data according to a first embodiment of the invention.
FIG. 4B shows timings of serial data according to a second embodiment of the invention.
FIG. 5 is a flow chart showing a method for transmitting random data according to the preferred embodiment of the invention.



DETAILED DESCRIPTION OF THE INVENTION
The invention provides a serial peripheral interface and a data transmitting method thereof, in which many control pins of the serial peripheral interface are utilized to achieve the serial data transmission through multiple input pins and multiple output pins, and enhance the overall behavior of data transmission.
FIG. 3 is a block diagram showing an example of a data transmission system 300 according to a preferred embodiment of the invention. Referring to FIG. 3, the data transmission system 300 includes an integrated circuit 310 and a serial peripheral interface 320. Take the integrated circuit 310 is a memory device as exemplified, but is not limited. The integrated circuit 310 may be any circuit having a function of storing data. When the integrated circuit 310 is the memory device, the integrated circuit 310 includes a data register 312, a memory cell array 314 and an output buffer 316. The memory cell array 314 stores data.
The serial peripheral interface 320 has many pins 321 to 324 which are coupled to the integrated circuit 310. The integrated circuit 300 receives an instruction using only the first pin 321 or the first pin 321, the second pin 322, the third pin 323, and the fourth pin 324 of the serial peripheral interface 320. The integrated circuit receives 300 an address using the first pin 321, the second pin 322, the third pin 323, and the fourth pin 324 of the serial peripheral interface 320. The instruction and the address are transmitted to the data register 312, temporarily stored in the data register 312, and then transmitted to the memory cell array 314.
When a read out data is read from the integrated circuit 310 (i.e., when the read out data is to be read from the memory cell array 314), the read out data is transmitted to the output buffer 316 from the memory cell array 314, and temporarily stored in the output buffer 316. Then the read out data is sent through the first pin 321, the second pin 322, the third pin 323, and the fourth pin 324 of the serial peripheral interface 320. There may exist multiple dummy cycles before the read out data is sent.
The multiple pins of the serial peripheral interface 320 substantially include the first pin 321 and the second pin 322. When the first pin 321 is not for transmitting the instruction, the address or the read out data, the first pin 321 is used to temporarily stop transmitting the read out data. When the second pin 322 is not for transmitting the instruction, the address or the read out data, the second pin 322 can prevent the read out data from being read from the memory cell array 314. The first pin 321 and the second pin 322 substantially pertain to the control pins in the conventional serial peripheral interface, and are utilized to achieve the transmission of a piece of serial data, including instructions, addresses, dummy cycles and multiple read out data, through multiple input pins and multiple output pins in this embodiment.
The serial peripheral interface 320 further includes a chip select pin 325 for outputting a chip select signal CS. When the voltage level of the chip select signal CS is low, the first pin 321 to the fourth pin 324 transmit the instruction, the address or the read out data. In addition, the serial peripheral interface 320 also includes a clock pin 326 for inputting a timing signal SCLK, and the first pin 321 to the fourth pin 324 transmit the instruction, the address or the read out data according to the timing signal. It is possible to utilize the first pin 321 to the fourth pin 324 to simultaneously transmit the instruction, the address or the read out data, or to utilize some of the first pin 321 to the fourth pin 324 to simultaneously transmit the instruction, the address or the read out data. Compared with the conventional serial peripheral interface, the serial peripheral interface 300 according to the embodiment of the invention can increase the overall data transmission rate at most three times.
The timing signal SCLK includes many timing pulses. The first pin 321 to the fourth pin 324 transmit data according to the timing pulses. In addition, the first pin 321 to the fourth pin 324 may also transmit the data at rising edges, falling edges or both of the timing pulses. That is, a selection of the function of the double data rate (DDR) is provided.
FIG. 4A shows timings of serial data according to a first embodiment of the invention. As shown in FIG. 4A, for example, the serial data includes an 8-bit instruction, a 24-bit address, n dummy cycles and multiple 8-bit read out data, wherein n is an integer greater than or equal to 0 and is not particularly restricted. In FIG. 4A, when the chip select signal CS is low, the timing signal SCLK has many timing pulses. The first pin 321 to the fourth pin 324 receive the serial data at the rising edges and the falling edges of the timing pulses.
The first pin 321 to the fourth pin 324 receive the 8-bit instruction at the timing pulse 0, and then receive the 24-bit address at the timing pulses 1 to 3, wherein this address is the initial address of the data to be read. Then, n dummy cycles are provided for buffering. Next, the multiple 8-bit read out data are read and outputted after the timing pulse n+3. Compared with the conventional serial peripheral interface, the data transmission rate of the first embodiment of the invention may be increased seven times. In FIG. 4A, the transmission of all of the instruction, the address, the dummy cycles and the read out data is made according to the function of the double data rate. However, the transmission of the instruction, the address, the dummy cycles or the read out data may be also individually made according to the function of the double data rate or not. For example, only the transmission of the read out data is made according to, without limitation to, the function of the double data rate.
FIG. 4B shows timings of serial data according to a second embodiment of the invention. As shown in FIG. 4B, the first pin 321 receives the 8-bit instruction at the timing pulse 0 to 7. Then the first pin 321 to the fourth pin 324 receive the 24-bit address at the timing pulses 8 to 10. Then, n dummy cycles are provided for buffering. Next, the multiple 8-bit read out data are read and outputted after the timing pulse n+10. The 8-bit instruction is received only by the first pin 321. The 24-bit address is received by the function of double data rate. The multiple 8-bit read out data are received without the function of double data rate. In the invention, whether the transmission of the instruction, the address, the dummy cycles or the read out data applies the function of double data rate is decided according to the practical requirement and not limited hereinabove.
The data transmitting method mentioned hereinabove is performed to transmit the continuous data. If the random data has to be transmitted, it is necessary to make a judgment according to the time, for which the voltage level of the chip select signal CS is kept high. FIG. 5 is a flow chart showing a method for transmitting random data according to the preferred embodiment of the invention. First, the instruction, the address, the dummy cycles and the read out data are sequentially transmitted in steps 510 to 540. Then, step 550 judges whether the voltage level of the chip select signal is continuously kept high for a period exceeding a predetermined time, such as 240 nanoseconds (ns). If the voltage level of the chip select signal is continuously kept high for a period not exceeding the predetermined time, it represents that the instruction is a random access instruction. So, the procedure goes back to step 520, and the address, the dummy cycles and the read out data are transmitted again. If the voltage level of the chip select signal is continuously kept high for a period exceeding the predetermined time, it represents that the data transmission ends.
The serial peripheral interface and the data transmitting method according to the embodiment of the invention utilize many control pins on the serial peripheral interface to perform the data transmitting operation with the integrated circuit. The integrated circuit may be any type circuit with the function of data storage. Consequently, the serial data transmission can be through the multiple input pins and the multiple output pins, and the overall performance of data transmission can be enhanced.
While the invention has been described by way of example and in terms of a preferred embodiment, it is to be understood that the invention is not limited thereto. On the contrary, it is intended to cover various modifications and similar arrangements and procedures, and the scope of the appended claims therefore should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements and procedures.

## Claims

1. A serial peripheral interface of an integrated circuit, the serial peripheral interface comprising:
a first transfer pin for receiving an instruction and an address;
a clock pin for inputting a plurality of timing pulses each having a rising edge and a falling edge; and
a second transfer pin for preventing data from being read from the integrated circuit, and transmitting the instruction, the address or data when the second transfer pin is not for preventing data from being read from the integrated circuit,
wherein after the first transfer pin receives the instruction, the integrated circuit receives the address through the first transfer pin in continuity with the receipt of the instruction; and
the first transfer pin receives the instruction at either of the rising edges and the falling edges of the timing pulses and receives the address at both of the rising edges and falling edges of the timing pulses.

2. The serial peripheral interface according to claim 1, wherein the integrated circuit receives the instruction under a control of selectively using only the first transfer pin or a combination of the first transfer pin, the second transfer pin, a third transfer pin, and a fourth transfer pin of the serial peripheral interface, the integrated circuit receives the address using the first transfer pin, the second transfer pin, the third transfer pin, and the fourth transfer pin of the serial peripheral interface, and the integrated circuit transmits data using the first transfer pin, the second transfer pin, the third transfer pin, and the fourth transfer pin of the serial peripheral interface.

3. The serial peripheral interface according to claim 1, wherein the integrated circuit receives the address through the first transfer pin and other transfer pin/pins in continuity with the receipt of the instruction.

4. The serial peripheral interface according to claim 1, wherein the receipt of the address at both of the rising and falling edges of the timing pulses is initiated by the instruction.

5. The serial peripheral interface according to claim 1, wherein the second transfer pin is for transmitting data associated with the address at both of the rising and falling edges of the timing pulses.

6. The serial peripheral interface according to claim 1, wherein the first transfer pin also transmits data associated with the address at both of the rising and falling edges of the timing pulses in a multiple mode.

7. A data transmitting method applied to a serial peripheral interface of an integrated circuit, the serial peripheral interface including a plurality of pins and a clock pin, the method comprising the steps of:
inputting a plurality of timing pulses by the clock pin;
receiving an instruction and an address by a first transfer pin of the plurality of pins, wherein the instruction is received at either of rising edges and falling edges of the timing pulses and the address is received at both of the rising edges or the falling edges of the timing pulses; and
preventing data from being read from the integrated circuit through a second transfer pin of the plurality of pins when the second transfer pin is not for transmitting the instruction, the address or data.

8. The method according to claim 7, further comprising the steps of:
receiving the instruction under a control of selectively using only the first transfer pin or a combination of the first transfer pin, the second transfer pin, a third transfer pin, and a fourth transfer pin of the serial peripheral interface;
receiving the address using the first transfer pin, the second transfer pin, the third transfer pin, and the fourth transfer pin of the serial peripheral interface; and
sending data using the first transfer pin, the second transfer pin, the third transfer pin, and the fourth transfer pin of the serial peripheral interface.

9. The method according to claim 7, wherein
the integrated circuit receives the address through the first transfer pin and other transfer pin/pins in continuity with the receipt of the instruction.

10. The method according to claim 7, further comprising a step of:
inputting a chip select signal by a chip select pin, and
transmitting the instruction, the address or data through at least part of the pins when a voltage level of the chip select signal is low.

11. The method according to claim 10, wherein when data is read from the integrated circuit and if the voltage level of the chip select signal is continuously high for a period not exceeding a predetermined time, the pins transmit a new address, a new dummy cycle and new data.

12. The method according to claim 7, further comprising the steps of: transmitting data associated with the address by the second transfer pin at both of the rising and falling edges of the timing pulses.

13. The method according to claim 7, further comprising transmitting data associated with the address by the first transfer pin at both of the rising and falling edges of the timing pulses in a multiple mode.

14. The method according to claim 7, wherein the step of receiving the address or data both at rising and falling edges of the timing pulses is initiated by the instruction.