Customized method and apparatus for streamlined testing a particular electrical circuit

Claim 2

An electrical circuit, comprising: a functional circuit for performing desired functions during normal operation of the electrical circuit; serial scanning circuitry coupled to said functional circuit to support testing of said functional circuit, said serial scanning circuitry being connectable to a test controller for permitting serial data transfer between the test controller and the electrical circuit; and control circuitry connected to said serial scanning circuitry and connectable to the test controller for, when connected to the test controller, permitting test signals to be transferred bidirectionally between said serial scanning circuitry and said functional circuit while serial data is being transferred in a continuous serial data stream between the test controller and said serial scanning circuitry, said control circuitry being operable independently of said serial scanning circuitry.

Claim 3

The circuit of claim 1, wherein said serial scanning circuitry includes a shift register having a plurality of serially connected bit positions, and wherein said control circuitry includes a counter operable to count through a cyclical count sequence having a number of count states equal to the number of bit positions in said shift register.

Claim 4

The circuit of claim 2, wherein said shift register is operable to provide test signals to said functional circuit.

Claim 5

The circuit of claim 2, wherein said shift register is operable to receive test signals from said functional circuit.

Claim 6

The circuit of claim 1, wherein said functional circuit is a digital circuit.

Claim 7

The circuit of claim 1, wherein said functional circuit is an analog circuit.

Claim 8

The circuit of claim 1, wherein said functional circuit is a mixed signal circuit including both analog and digital circuit components.

Claim 9

An electrical circuit, comprising: a functional circuit for performing desired functions during normal operation of the electrical circuit; serial scanning circuitry coupled to said functional circuit to support testing of said functional circuit, said serial scanning circuitry being connectable to a test controller for permitting serial data transfer between the test controller and the electrical circuit; and control circuitry connected to said serial scanning circuitry and connectable to the test controller for, when connected to the test controller, permitting test signals to be transferred bidirectionally between said serial scanning circuitry and said functional circuit while serial data is being transferred in a continuous serial data stream between the test controller and said serial scanning circuitry, said control circuitry being operable without receiving externally provided information regarding said functional circuit.

Claim 10

An electrical circuit, comprising: a functional circuit for performing desired functions during normal operation of the electrical circuit; serial scanning circuitry coupled to said functional circuit to support testing of said functional circuit, said serial scanning circuitry being connectable to a test controller for permitting serial data transfer between the test controller and the electrical circuit; and control circuitry connected to said serial scanning circuitry and connectable to the test controller for, when connected to the test controller, permitting test signals to be transferred bidirectionally between said serial scanning circuitry and said functional circuit while serial data is being transferred in a continuous serial data stream between the test controller and said serial scanning circuitry, said control circuitry being operable without receiving externally provided information regarding said functional circuit.

Claim 11

The circuit of claim 8, wherein said serial scanning circuitry includes a shift register having a plurality of serially connected bit positions, and wherein said control circuitry includes a counter operable to count through a cyclical count sequence having a number of count states equal to the number of bit positions in said shift register.

Claim 12

The circuit of claim 9, wherein said shift register is operable to provide test signals to said functional circuit.

Claim 13

The circuit of claim 9, wherein said shift register is operable to receive test signals from said functional circuit.

Claim 14

The circuit of claim 9, wherein said counter counts at the same rate as said shift register shifts.

Claim 15

The circuit of claim 9, wherein said control circuitry includes logic connected to said counter and said shift register to provide a control signal to said shift register in response to a predetermined count state of said counter.

Claim 16

The circuit of claim 13, wherein said shift register is operable to provide test signals to said functional circuit.

Claim 17

The circuit of claim 13, wherein said shift register is operable to receive test signals from said functional circuit.

Claim 18

The circuit of claim 9, wherein said serial scanning circuitry includes a further shift register, and wherein one of said shift registers is operable to provide test signals to said functional circuit and the other of said shift registers is operable to receive test signals from said functional circuit, wherein said counter counts at the same rate as said shift registers shift, and wherein said control circuitry includes logic connected to said counter and said other shift register to provide said other shift register with a shift clock signal in response to a predetermined count state of said counter.

Claim 19

The circuit of claim 16, wherein said logic is operable to provide control signals to both of said shift registers in response to respective predetermined count states of said counter.

Claim 20

The circuit of claim 8, wherein said functional circuit is a digital circuit.

Claim 21

The circuit of claim 8, wherein said functional circuit is an analog circuit.

Claim 22

The circuit of claim 8, wherein said functional circuit is a mixed signal circuit including both analog and digital circuit components.