System having input output pins shifting between programming mode and normal mode to program memory without dedicating input output pins for programming mode
First Claim
1. A device implemented to be programmed in accordance with instruction words entered as digital bits after installation of the device in circuit with a system to be controlled by the device, comprising:
- a microcontroller for controlling the system,a programmable memory for the microcontroller,means responsive to instruction words entered into the device for programming the memory while the device is installed in circuit with the system to be controlled, including means for enabling suppression of perturbations of the system which would otherwise occur during in-circuit programming so as to avoid effects on system operation while the programming is taking place;
a plurality of input/output (I/O) pins for receiving data including instruction words to be entered into the device, the number of I/O pins being smaller than the number of bits in an instruction word wherein at least some of said I/O pins are dual function and are shifted between a programming mode and a normal mode; and
mode selection means associated with said at least some of the I/O pins but less than all of the I/O pins, for selectively enabling said at least some of the I/O pins to additionally function to receive data serially when in said programming mode for purposes of programming the memory while the other I/O pins are adapted to receive data in parallel thereby eliminating the need for dedicated programming I/O pins.
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Accused Products
Abstract
A microcontroller and associated EPROM program memory are fabricated in a single semiconductor chip. The microcontroller device is adapted to be programmed using digital command words or other bit patterns applied as inputs after installation of the device in circuit with a system to be controlled by the device, and to have its programming pins isolated from the system to avoid effects on system operation while the programming is taking place. The in-circuit programming uses considerably less than the total number of input/output (I/O) pins of the device, which in total are fewer than the number of bits in a command word. This is achieved with a serial/parallel programming interface between the pins and the program memory, and by applying the data in serial fashion to the interface where it is latched and loaded in parallel in the memory. Input data to the device may alternatively be entered in parallel to the interface in bytes of width less than the total number of I/O pins of the device.
87 Citations
10 Claims
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1. A device implemented to be programmed in accordance with instruction words entered as digital bits after installation of the device in circuit with a system to be controlled by the device, comprising:
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a microcontroller for controlling the system, a programmable memory for the microcontroller, means responsive to instruction words entered into the device for programming the memory while the device is installed in circuit with the system to be controlled, including means for enabling suppression of perturbations of the system which would otherwise occur during in-circuit programming so as to avoid effects on system operation while the programming is taking place; a plurality of input/output (I/O) pins for receiving data including instruction words to be entered into the device, the number of I/O pins being smaller than the number of bits in an instruction word wherein at least some of said I/O pins are dual function and are shifted between a programming mode and a normal mode; and mode selection means associated with said at least some of the I/O pins but less than all of the I/O pins, for selectively enabling said at least some of the I/O pins to additionally function to receive data serially when in said programming mode for purposes of programming the memory while the other I/O pins are adapted to receive data in parallel thereby eliminating the need for dedicated programming I/O pins. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A programmable semiconductor microcontroller chip for installing into and to control an electrically operated system, comprising:
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a plurality of input/output (I/O) pins for receiving instruction words and data entered in the form of electrical signals to be processed by the microcontroller chip, the total number of said I/O pins is less than the number of bits in an instruction word, an on-chip programmable memory adapted to be programmed by instruction words received as inputs to the microcontroller chip at the (I/O) pins, means for selectively implementing electrical isolation of at least some of the I/O pins from the system to be controlled by the microcontroller chip, to suppress disturbances to the system when the memory is being programmed with the microcontroller chip installed in the system; and interface means for selectively responding to instruction words entered via at least some of said I/O pins in either serial or parallel fashion to program the programmable memory wherein said at least some of said I/O pins are dual function for shifting the chip between a programming mode and a normal mode, such that during said programming mode said at least some of said I/O pins are used to program said on-chip programming memory and during said normal mode said at least some of said I/O pins are used for inputting and outputting data appropriate for implementing control of the system in which the microcontroller chip is installed, thereby eliminating the need for dedicated programming I/O pins. - View Dependent Claims (9)
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10. A method of programming a programmable microcontroller for installing into and for controlling an electrically operated system, while the microcontroller is installed within the system, the microcontroller having a plurality of input ports, the method comprising the steps of:
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selecting at least some of the input ports for performing a dual function according to whether the microcontroller is operating in a normal mode or a programming mode and thereby eliminating the need for dedicated programming pins, using said at least some of the input ports for receiving instruction words to be entered in the microcontroller while in said normal mode, the number of input ports being smaller than the number of bits in an instruction word using said at least some of the input ports for receiving data serially to be used to program the microcontroller while in said program mode; and
,substantially isolating electrical levels associated with programming the microcontroller from the circuit of the system to be controlled, with the microcontroller installed in circuit with the system, to preclude disturbances to the system during the in-system programming.
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Specification