US5675534A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for preventing unauthorized access to nonvolatile memory in electronic encoders having a voltage level detection circuit
Assignee: Microchip Technology Inc
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Filing: 1996-03-05
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Granted: 1997-10-07
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Expires: 2016-03-05
Abstract
Abstract According to the present invention, a method is provided for reading data from non-volatile memory in an electronic encoding device such that unauthorized access to the data is prevented. In one embodiment, the method includes the steps of writing a first set of data to the non-volatile memory; generating a voltage detect signal during the writing, the voltage detect signal being representative of a source voltage applied to the non-volatile memory; determining whether the writing was successful by evaluating the voltage detect signal; and reading data from the non-volatile memory responsive to the determination.
Inventors
- 👤 Kent Hewitt
- 👤 Willem Smit
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 22:51
CPC Classifications
G; G11; G11C; G11C16/00; G11C16/02; G11C16/06; G11C16/22
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
80 words
A method for reading data from non-volatile memory in an electronic encoding device such that unauthorized access to the data is prevented, the method comprising: writing a first set of data to the non-volatile memory; generating a voltage detect signal during the writing, the voltage detect signal being representative of a source voltage applied to the non-volatile memory; determining whether the writing was successful by evaluating the voltage detect signal; reading data from the non-volatile memory responsive to the determination.
Claim 2
Independent Claim
80 words
A method for reading data from non-volatile memory in an electronic encoding device such that unauthorized access to the data is prevented, the method comprising: writing a first set of data to the non-volatile memory; generating a voltage detect signal during the writing, the voltage detect signal being representative of a source voltage applied to the non-volatile memory; determining whether the writing was successful by evaluating the voltage detect signal; reading data from the non-volatile memory responsive to the determination.
Claim 3
Independent Claim
89 words
A system for reading data from non-volatile memory in an electronic encoding device such that unauthorized access to the data is prevented, the system comprising: means for writing a first set of data to the non-volatile memory; means for generating a voltage detect signal during the writing, the voltage detect signal being representative of a source voltage applied to the non-volatile memory; means for determining whether the writing was successful by evaluating the voltage detect signal; and means for reading data from the non-volatile memory responsive to the determination.
Claim 4
Independent Claim
89 words
A system for reading data from non-volatile memory in an electronic encoding device such that unauthorized access to the data is prevented, the system comprising: means for writing a first set of data to the non-volatile memory; means for generating a voltage detect signal during the writing, the voltage detect signal being representative of a source voltage applied to the non-volatile memory; means for determining whether the writing was successful by evaluating the voltage detect signal; and means for reading data from the non-volatile memory responsive to the determination.
Claim 5
Dependent Claim
65 words
An electronic encoding device comprising: a non-volatile memory; a controller coupled to the non-volatile memory; encoder logic coupled to the non-volatile memory; input logic coupled to the controller; output logic coupled to the non-volatile memory; and a voltage level detection circuit coupled to the non-volatile memory, which provides a signal responsive to a non-volatile memory write voltage to enable a read from said non-volatile memory.
Claim 6
Dependent Claim
65 words
An electronic encoding device comprising: a non-volatile memory; a controller coupled to the non-volatile memory; encoder logic coupled to the non-volatile memory; input logic coupled to the controller; output logic coupled to the non-volatile memory; and a voltage level detection circuit coupled to the non-volatile memory, which provides a signal responsive to a non-volatile memory write voltage to enable a read from said non-volatile memory.
Claim 7
Dependent Claim
65 words
An electronic encoding device as in claim 3 wherein the voltage level detection circuit comprises: a pair of series connected P-channel transistors, each transistor having a first threshold voltage; an N-channel transistor having a second threshold voltage; the N-channel transistor being in series with the pair of P-channel transistors; a voltage detect signal path connected between a source of the N-channel transistor and the controller.
Claim 8
Independent Claim
80 words
A method for reading data from non-volatile memory in an electronic encoding device such that unauthorized access to the data is prevented, the method comprising: writing a first set of data to the non-volatile memory; generating a voltage detect signal during the writing, the voltage detect signal being representative of a write voltage applied to the non-volatile memory; determining whether the writing was successful by evaluating the voltage detect signal; reading data from the non-volatile memory responsive to the determination.
Claim 9
Independent Claim
80 words
A method for reading data from non-volatile memory in an electronic encoding device such that unauthorized access to the data is prevented, the method comprising: writing a first set of data to the non-volatile memory; generating a voltage detect signal during the writing, the voltage detect signal being representative of a write voltage applied to the non-volatile memory; determining whether the writing was successful by evaluating the voltage detect signal; reading data from the non-volatile memory responsive to the determination.
Claim 10
Dependent Claim
76 words
An electronic encoding device comprising: and non-volatile memory; a controller coupled the non-volatile memory; encoder logic coupled to the non-volatile memory; input logic coupled to the controller; output logic coupled to the non-volatile memory; and a voltage level detection circuit coupled to the non-volatile memory, which provides a signal responsive to a source voltage applied to the non-volatile memory, during writing to said non-volatile memory the signal being enabling of a read from said non-volatile memory.
Claim 11
Dependent Claim
76 words
An electronic encoding device comprising: and non-volatile memory; a controller coupled the non-volatile memory; encoder logic coupled to the non-volatile memory; input logic coupled to the controller; output logic coupled to the non-volatile memory; and a voltage level detection circuit coupled to the non-volatile memory, which provides a signal responsive to a source voltage applied to the non-volatile memory, during writing to said non-volatile memory the signal being enabling of a read from said non-volatile memory.
References Cited (Backward Citations)
US5554977A
Cited
US5301161A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2000-10-06 | 2001-04-07 | 2001-10-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-10-06 | 2005-04-07 | 2005-10-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-10-06 | 2009-04-07 | 2009-10-07 | $7700.00 | Window Closed / Lapsed |