US 2006/0190791 A1 · Enabling special modes within a digital device

Abstract

A special mode key match comparison module has N-storage elements and a special mode key match comparator. The N-storage elements accumulate a serial data stream, and then determine whether a digital device should operate in a normal user mode, in a public programming mode, or in a particular private test mode. To reduce the possibility of accidentally decoding a false test or programming mode, the data stream has a sufficiently large number of N-bits to substantially reduce the probability of a false decode. To further reduce the possibility of accidentally decoding a programming or test mode, the special mode key match comparison module may be reset if less or more than N-clocks are detected during the accumulation of the N-bit serial data stream. The special mode key match data patterns may represent a normal user mode, a public programming mode, and particular private manufacturer test modes.

Claims29

Dependent claims

An apparatus for enabling special modes within a digital device, comprising:

N-storage elements having N-outputs, a clock input and a serial data input;
the N-storage elements are adapted to accumulate N-bits of serial data during N-clocks, wherein the N-outputs being representative of the accumulated N-bits of serial data;
a special mode key match comparator coupled to the N-outputs of the N-storage elements;
the special mode key match comparator has at least one special mode key match data pattern for at least one special mode of a digital device;
and
the special mode key match comparator compares the accumulated N-bits of serial data with the at least one special mode key match data pattern, and if the accumulated N-bits of serial data match a one of the at least one special mode key match data pattern then the special mode key match comparator outputs a special mode code representative of the at least one special mode and a special mode active to the digital device.

3 more elements

Dependencies are inferred from the claim text.

Enabling special modes within a digital device

Life of this patent

Enabling special modes within a digital device

Life of this patent

Abstract

Claims29