JPH02181950A - System of setting operation mode of semiconductor integrated circuit - Google Patents

Abstract

PURPOSE:To set a specific operation mode from a plurality of operation modes by providing one shift register which has been connected from one operation- mode setting terminal. CONSTITUTION:A shift register 4 which uses a mode-setting terminal 1 of a semiconductor integrated circuit as a data input is constituted in such a way that a data is shifted by a signal, of a shift clock signal line, generated at an AND circuit 6 by individual input signals to a clock input terminal 2 and to a reset input terminal 3. An input data 1' for operation-mode setting use is input from the mode-setting terminal 1 in synchronization with the signal of the shift clock signal line 7. A shift clock 7' is generated as an output signal from the AND circuit 6 by a clock 2' and a reset signal 3' which is input from the reset terminal 3. The clock 2' is a system clock which operates a semiconductor integrated circuit and is always oscillated. A data from individual flip- flops 8 constituting the shift register 4 is output from an output terminal 5; an operation mode is judged at the inside of the semiconductor integrated circuit when a reset is released.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an operating mode setting method for semiconductor integrated circuits. The operating mode was set by applying a setting signal to a combination of terminal states or by applying a setting signal at a special timing. Therefore, when setting an operating mode by giving a specific setting signal to a terminal, the number of operating modes that can be set is N2, where the number of terminals is N, and depending on the operating mode of the semiconductor integrated circuit, many terminals are required. .

Problems to be Solved by the Invention In the conventional method of setting the operating mode using multiple terminals, it is necessary to allocate many terminals for mode setting, and in the method of setting at special timing, the mode setting procedure is extremely complicated. It was difficult.

The present invention solves the above conventional problems and provides a method for setting a plurality of operation modes using a single operation mode setting terminal without a complicated setting method.

Means for Solving the Problems In order to achieve this object, the present invention includes one operation mode setting terminal and one shift register connected to the inside of the semiconductor integrated circuit from the setting terminal. This is a method of setting a specific operation mode from multiple operation modes depending on the value.

Effect: With this configuration, a specific operation mode can be set using a single operation mode setting pin, and the operation mode of the semiconductor integrated circuit can be freely set without using multiple mode setting pins or special timing. Can be done.

Example An embodiment of the present invention will be described below.

FIG. 1 shows the circuit configuration of the present invention.

A shift register 4 whose data input is a mode setting terminal 1 of a semiconductor integrated circuit is connected to an AND circuit 6 by input signals to a clock input terminal 2 and a reset input terminal 3.
Data is shifted by a signal on a shift clock signal line 7 generated by a shift clock signal line 7.

The operation mode setting method of the semiconductor integrated circuit configured as described above will be explained using the timing chart of each input signal in FIG. Operation mode setting input data 1' is inputted from the mode setting terminal 1 of the semiconductor integrated circuit in synchronization with the signal on the shift clock signal line 7. The signal on the shift clock signal line 7 (shift clock 7'') is an AND of the clock 2' and the reset signal 3' input from the reset terminal 3.
It is generated as an output signal from circuit 6. Clock 2' is a system clock that operates the semiconductor integrated circuit, and is always activated. It is assumed that the reset signal 3' is "1" at the time of reset and "O" when the reset is released.

The logic 1 (A
ND), the shift clock 7' is generated, so when the reset signal 3 is "1", the system clock 7' outputs the same signal as the clock 2', but when the reset signal 3' is "O" The clock 7' remains 0''. Therefore, the input data 1'' for setting the operation mode is generated when the system clock 7'' is generated, that is, the reset signal 3
When ゛ is “1”, it is input in synchronization with the system clock 7゛, and when all the input data 1° for operation mode setting has been input, the reset signal 3′ is set to “0” and the data is transferred to the shift register 4. hold within. Data from each flip-flop 8 constituting the shift register 4 is output from the output terminal 5, and the operation mode is determined inside the semiconductor integrated circuit when reset is released.

As described above, by providing one shift register connected to one operation mode setting terminal, the operation mode can be set.

In this embodiment, the shift register has 4 bits, but the number of flip-flops constituting the shift register can be easily changed depending on the number of operation modes. Further, although the type of the flip-flop is not particularly specified, there is no restriction as long as it can constitute a shift register.

Effects of the Invention As described above, the present invention provides an operating mode for a semiconductor integrated circuit that can set a specific operating mode from a plurality of operating modes by providing one shift register connected to one operating mode setting terminal. It is possible to realize a setting method.

[Brief explanation of the drawing]

FIG. 1 is a circuit configuration diagram of an embodiment of the present invention, and FIG. 2 is a timing diagram of each signal in an embodiment of the present invention. 1...Mode setting terminal of semiconductor integrated circuit, 2.
... Clock input terminal, 3 ... Reset input terminal, 4 ... Shift register, 5 ...
...Output terminal from the flip-flop configuring the shift register, 6...AND circuit, 7...
...Shift clock signal line, 8...Flip-flops forming the shift register. Name of agent: Patent attorney Shigetaka Awano and 1 other person 3g-

Claims (2)

[Claims] (1) It is equipped with one operation mode setting terminal and has a plurality of operation modes, and by inputting a specific operation mode setting signal from the terminal, one of the plurality of operation modes can be selected.
An operating mode setting method for semiconductor integrated circuits that determines two operating modes. (2) Claim (1) characterized by comprising one shift register connected to one operation mode setting terminal, and setting a specific operation mode from a plurality of operation modes according to the value of this shift register. Operation mode setting method of the semiconductor integrated circuit described.