Event driven scanning of data input equipment using multi-input wake-up techniques

• US 5,355,503 A
• Filed: 10/13/1993
• Issued: 10/11/1994
• Est. Priority Date: 05/31/1990
• Status: Expired due to Term

• Current Assignee: National Semiconductor Corporation (Texas Instruments, Inc.)
• Original Assignee: National Semiconductor Corporation (Texas Instruments, Inc.)
• Inventors: Soffel, Volker, Rothhaupt, Thomas
• Primary Examiner(s): MacDonald, Allen R.
• Assistant Examiner(s): AUVE, GLENN ALLEN
• Application Number:
  US08/136,475
• Time in Patent Office: 363 Days
• Field of Search: 395/750, 395/575, 395/550, 371/66, 364/707, 364/273.1, 364/DIG. 1, 364/948.8, 364/DIG. 2
• US Class Current: 713/322
• CPC Class Codes: G06F 1/3215 Monitoring of peripheral devices

Abstract

An event driven wake-up system for controlling current consumption by a microcontroller that controls a data input device used to enter data to a data processing system is provided. The wake-up system include a data input device, such as a keyboard, that is responsive to an external event, such as depression of a key on the keyboard, by providing a signal indicative of the occurrence of the external event. The microcontroller responds to the external event by generating a data character that corresponds to the signal received from the data input device and provides that data character to the CPU of the data processing system. The microcontroller includes means for sensing inactivity at the data input device and for entering the microcontroller into a reduce current consumption mode when such inactivity is sensed. Wake-up logic responds to an input signal from the data input device and/or from the data processing system when the microcontroller is in the reduced current consumption mode by providing a wake-up signal that removes the microcontroller from the reduced current consumption mode.

Claims

1. A microcontroller that executes a sequence of instructions in response to clock signals provided by a clock generator and that controls a data input device used to enter data into a data processing system, an address of a currently executing instruction in the sequence of instructions being stored in a program counter, the program counter being incremented during the execution of the currently executing instruction to indicate an address of the next instruction in the sequence of instructions, the microcontroller being operable in a plurality of current consumption modes which it cycles among in response to external events indicative of activity or indicative of an absence of activity of data entry to or data processing by the data processing system, the microcontroller operating in a normal current consumption mode during data entry to the data processing system, and the microcontroller being responsive to an external event by generating an active signal indicative of an occurrence of the external event, the microcontroller comprising:

(a) halt means for initiating a reduced current consumption mode, wherein said halt means responds to an event indicative of inactivity at the data input device by generating a halt signal, the microcontroller being responsive to the halt signal by deactivating the clock means and thereby suspending execution of the sequence of instructions and by entering a reduced current consumption mode; and

(b) wake-up means for returning the microcontroller to the normal current consumption mode, wherein said wake-up means responds to an active signal generated by the data input device when the microcontroller has entered the reduced current consumption mode by generating a wake-up signal, the microcontroller being responsive to the wake-up signal by activating the clock generator and thereby resuming execution of the sequence of instructions, where the first instruction executed upon wake-up is an instruction the address of which is stored in the program counter as a result of the microcontroller executing the instruction which was last executed prior to entering the reduced current consumption mode, and by returning from the reduced current consumption mode to the normal current consumption mode.

2. A microcontroller as in claim 1 wherein the data input device is a keyboard with keys which can be depressed and the external event is the depression of a key on the keyboard.

3. A microcontroller as in claim 1 wherein the data input device is a keyboard and the external event is receipt of data from the data processing system.

4. An event driven wake-up system for controlling current consumption by a data processing system, the event driven wake-up system being operable in a plurality of current consumption modes which it cycles among in response to external events indicative of activity or indicative of an absence of activity of data entry to or data processing by the data processing system, the event driven wake-up system comprising:

(a) a data input device that responds to an external event indicative of activity or inactivity of data entry to or data processing by the data processing system by generating an active signal indicative of an occurrence of the external event;

(b) a microcontroller for controlling the data input device, the microcontroller executing a sequence of instructions in response to clock signals provided by a clock generator, an address of a currently executing instruction in the sequence of instructions being stored in a program counter, the program counter being incremented during the execution of the currently executing instruction to indicate an address of the next instruction in the sequence of instructions, the microcontroller being operable in a plurality of current consumption modes and cycling among the modes in response to the occurrence of the external event;

(c) halt means for initiating a reduced current consumption mode, wherein said halt means responds to an event indicative of inactivity at the data input device by generating a halt signal, the microcontroller being responsive to the halt signal by deactivating the clock generator and thereby suspending execution of the sequence of instructions and by entering a reduced current consumption mode; and

(d) wake-up means for returning the event driven wake-up system to the normal current consumption mode, wherein said wake-up means is responsive to an active signal provided by the data input device when the microcontroller means has entered the reduced current consumption mode, the wake-up means providing a wake-up signal that activates the clock generator and thereby causes the microcontroller to resume execution of the sequence of instructions, where the first instruction executed upon wake-up is an instruction the address of which is stored in the program counter as a result of the microcontroller executing the instruction which was last executed prior to entering the reduced current consumption mode, and returns the microcontroller from the reduced current consumption mode to the normal current consumption mode.

5. An event driven wake-up system as in claim 4 wherein the data input device is a keyboard with keys which can be depressed and the external event is the depression of a key on the keyboard.

6. An event driven wake-up system as in claim 4 wherein the data input device is a keyboard and the external event is receipt of data from the data processing system.

7. A data processing system comprising:

(a) a central processing unit for processing data entered into the data processing system;

(b) a data input device for entering data into the data processing system, the data input device being responsive to an external event by generating an active signal indicative of an occurrence of the external event;

(c) a microcontroller that controls the data input device, the microcontroller executing a sequence of instructions in response to clock signals provided by a clock generator, an address of a currently executing instruction in the sequence of instructions being stored in a program counter, the program counter being incremented during the execution of the currently executing instruction to indicate an address of the next instruction in the sequence of instructions, the microcontroller being operable in a plurality of current consumption modes which it cycles among in response to external events indicative of activity or an absence of activity of data entry to the data processing system or data processing by the data processing system, with the microcontroller operating in a normal current consumption mode for data entry to the data processing system;

(d) halt means for initiating a reduced current consumption mode, wherein said halt means responds to an event indicative of inactivity at the data input device by generating a halt signal, the microcontroller being responsive to the halt signal by deactivating the clock generator and thereby suspending execution of the sequence of instructions and by entering a reduced current consumption mode; and

(e) wake-up means for returning the microcontroller to the normal current consumption mode, wherein said wake-up means responds to an active signal generated by the data input device when the microcontroller is in the reduced current consumption mode by generating a wake-up signal, the microcontroller being responsive to the wake-up signal by activating the clock generator and thereby resuming execution of the sequence of instructions, where the first instruction executed upon wake-up is an instruction the address of which is stored in the program counter as a result of the microcontroller executing the instruction which was last executed prior to entering the reduced current consumption mode, and by returning from the reduced current consumption mode to the normal current consumption mode.

8. A data processing system as in claim 7 wherein the data input device is a keyboard with keys which can be depressed and the external event is depression of a key on the keyboard.

9. A data processing system as in claim 7 wherein the data input device is a keyboard and the external event is receipt of data from the central processing unit.