# US 10,371,749 B1 · Removal of over-masking in an on product multiple input signature register (OPMISR) test

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- Number: US 10,371,749 B1
- Document ID: US10371749B1
- Status: Granted
- Kind: B1
- Application number: 16/119,458
- Filed: 2018-08-31
- Granted: 2019-08-06
- Earliest claimed: 2018-08-31
- Assignees: International Business Machines Corporation
- Applicants: International Business Machines Corporation
- Inventors: Steven M. Douskey; Mary P. Kusko; Amanda R. Kaufer; Michael J. Hamilton; Matthew B. Schallhorn
- Web page: https://patentgrep.com/patent/US10371749B1

## CPC

- G01R 31/3177: Testing of logic operation, e.g. by logic analysers
- G01R 31/318566: {Comparators; Diagnosing the device under test}
- G01R 31/3172: {Optimisation aspects, e.g. using functional pin as test pin, pin multiplexing}
- G01R 31/318583: {Design for test}
- G06F 30/327: Logic synthesis; Behaviour synthesis, e.g. mapping logic, HDL to netlist, high-level language to RTL or netlist
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)

## Abstract

A method and test circuit are provided for implementing enhanced scan data testing with removal of over masking in an on product multiple input signature register (OPMISR) test, and a design structure on which the subject circuit resides. Common Channel Mask Scan Registers (CMSR) data is used with a multiple input signature register (MISR) in each satellite. A test algorithm control is used for implementing enhanced scan data testing to allow sharing the CMSR data and common Channel Mask Enable (CME) pins with removal of over masking. Selectively pausing scan unload is provided for each respective satellite when wrong CME data for the respective satellite is at the CME pins. Each satellite includes a select signal which controls advancing the scan into the MISR. The select signal is used to selectively pause the scan unload for the respective satellite.

## Claims

### Claim 1

A method for implementing enhanced scan data testing with over masking removal in an on product multiple input signature register (OPMISR) comprising:
providing a plurality of OPMISR satellites, each of the plurality of OPMISR satellites including a multiple input signature register (MISR) for data collection and a plurality of associated scan channels;
providing common Channel Mask Scan Registers (CMSR) data and common Channel Mask Enable (CME) pins with the multiple input signature register (MISR) in each OPMISR satellite;
providing a select signal in each OPMISR satellite, where said select signal controls advancing the scan unload into the MISR;
using an algorithm for implementing enhanced scan data testing by selectively pausing scan unload for each respective selected OPMISR satellite; and
using said select signal in respective satellite channels to selectively pause the scan unload for the respective OPMISR satellite when wrong CME data for the respective OPMISR satellite is at the CME pins for avoiding over masking.

### Claim 2 (depends on 1)

The method as recited in claim 1, wherein using said algorithm for implementing enhanced scan data testing enables data volume reduction and minimizing over masking.

### Claim 3 (depends on 1)

The method as recited in claim 1, wherein selectively pausing scan unload for each respective selected OPMISR satellite comprises identifying CME values for each OPMISR satellite for each scan unload bit position for use to determine an order of satellite selection and CMEs.

### Claim 4 (depends on 3)

The method as recited in claim 3, further comprising starting operations with a first scan unload bit position across all OPMISR satellites.

### Claim 5 (depends on 4)

The method as recited in claim 4, further comprising for each OPMISR satellite with data ready at unload, determining if all CMEs match for all the OPMISR satellites.

### Claim 6 (depends on 4)

The method as recited in claim 4, further comprising when all CMEs match for all the OPMISR satellites, unloading all the OPMISR satellites for one scan cycle.

### Claim 7 (depends on 4)

The method as recited in claim 4, further comprising when all CMEs do not match for all the OPMISR satellites, determining if any CMEs match for respective OPMISR satellites.

### Claim 8 (depends on 7)

The method as recited in claim 7, further comprising unloading one OPMISR satellite when there are no CMEs matches.

### Claim 9 (depends on 7)

The method as recited in claim 7, further comprising when some CMEs match, selecting the corresponding OPMISR satellites of the matching CMEs for unload.

### Claim 10 (depends on 9)

The method as recited in claim 9, further comprising selectively pausing scan unload of other respective OPMISR satellite or OPMISR satellites.

### Claim 11

A test circuit for implementing enhanced scan data testing with over masking removal in an on product multiple input signature register (OPMISR) comprising:
a plurality of OPMISR+ satellites, each of the plurality of OPMISR+ satellites including a multiple input signature register (MISR) for data collection and a plurality of associated scan channels;
common Channel Mask Scan Registers (CMSR) data and common Channel Mask Enable (CME) pins with the multiple input signature register (MISR) in each OPMISR+ satellite;
a select signal in each OPMISR+ satellite, where said select signal controls advancing the scan unload into the MISR;
a processor; and
a test algorithm control logic, which when implemented causes the processor to:
selectively pause scan unload for each respective selected OPMISR+ satellite by utilizing said select signal to pause the scan unload for a respective OPMISR+ satellite when wrong CME data for the respective OPMISR+ satellite is at the CME pins, thereby avoiding over masking.

### Claim 12 (depends on 11)

The test circuit as recited in claim 11, further comprising control code stored on a computer readable medium, and wherein said processor uses the control code for implementing enhanced scan data testing.

### Claim 13 (depends on 11)

The test circuit as recited in claim 11, said test algorithm control logic to selectively pause the scan unload for each respective selected OPMISR+ satellite comprises logic to identify CME values for each OPMISR+ satellite for each scan unload bit position for use to determine an order of satellite selection and CMEs.

### Claim 14 (depends on 13)

The test circuit as recited in claim 13, wherein said test algorithm control logic to selectively pause the scan unload for each respective selected OPMISR+ satellite further comprises logic to start operations with a first scan unload bit position across all OPMISR+ satellites.

### Claim 15 (depends on 14)

The test circuit as recited in claim 14, wherein said test algorithm control logic to selectively pause the scan unload for each respective selected OPMISR+ satellite further comprises logic to, for each OPMISR+ satellite with data ready at unload, determine if all CMEs match for all the OPMISR+ satellites.

### Claim 16 (depends on 14)

The test circuit as recited in claim 14, wherein said test algorithm control logic to selectively pause the scan unload for each respective selected OPMISR+ satellite further comprises logic to unload all the satellites for one scan cycle when all CMEs match for all the OPMISR+ satellites.

### Claim 17 (depends on 14)

The test circuit as recited in claim 14, wherein said test algorithm control logic to selectively pause the scan unload for each respective selected OPMISR+ satellite further comprises logic to, when all CMEs do not match for all the OPMISR+ satellites, determine if any CMEs match for respective OPMISR+ satellites.

### Claim 18 (depends on 17)

The test circuit as recited in claim 17, wherein said test algorithm control logic to selectively pause the scan unload for each respective selected OPMISR+ satellite further comprises logic to unload one OPMISR+ satellite when there are no CMEs matches.

### Claim 19 (depends on 18)

The test circuit as recited in claim 18, wherein said test algorithm control logic to selectively pause the scan unload for each respective selected OPMISR+ satellite further comprises logic to, when some CMEs match, select the corresponding OPMISR+ satellites of the matching CMEs for unload.

### Claim 20 (depends on 19)

The test circuit as recited in claim 19, wherein said test algorithm control logic to selectively pause the scan unload for each respective selected OPMISR+ satellite further comprises logic to selectively pause scan unload of other respective OPMISR+ satellite or OPMISR+ satellites.