System and method for testing memory blocks in an SOC design
View Patent ↗A system and method for testing a plurality of memory blocks in a System on Chip (SOC) design uses two Test Access Ports (TAPs); a user TAP and an EDA tool TAP, to provide instructions and test data to the SOC. The system includes a glue logic block, a secured logic block and a memory testing module. The glue logic block selects the user TAP at the outset of the testing phase. The secured logic block is coupled with the user TAP and generates a TAP selection signal, which controls the selection of the EDA tool TAP. The memory testing module is used to carry out the process of testing the memory blocks when the EDA tool TAP is selected.
1. A system for testing a plurality of memory blocks in a System on Chip (SOC) having at least two Test Access Ports (TAPs), the two TAPs including a user TAP and an Electronic Design Automation (EDA) tool TAP, wherein the EDA tool TAP is used to access and test the memory blocks of the SOC, and wherein the user TAP and the EDA tool TAP are accessed using one set of JTAG pins including a TDI, TCK, TMS and TRST pin, the system comprising:
a glue logic block that selects the user TAP at an outset of a testing phase and after programming the user TAP selects the EDA tool TAP to provide test data received via the TDI pin to the plurality of memory blocks during testing of the plurality of memory blocks;
a secured logic block in communication with the user TAP by way of the glue logic block that generates a TAP selection signal, wherein the TAP selection signal is gated with the TMS pin in order to control selection of the user TAP and the EDA tool TAP and thereby prevent non-privileged access to the plurality of memory blocks via the EDA tool tap;
a memory testing module in communication with the EDA tool TAP by way of the glue logic block for facilitating testing of the plurality of memory blocks when the EDA tool TAP is selected, wherein the memory testing module receives test data from the EDA tool TAP; and
a fuse logic block, including at least one fuse, connected to the secured logic block, wherein blowing the at least one fuse prevents the secured logic block from asserting the TAP selection signal, thereby disabling access to the EDA tool TAP so that the memory blocks can no longer be accessed via the EDA tool TAP.
2. The system for testing memory blocks of claim 1 , wherein the glue logic block receives the TAP selection signal from the secured logic block and uses the TAP selection signal to select the EDA tool TAP.
3. The system for testing memory blocks of claim 1 , wherein the secured logic block comprises:
a control register that stores one or more bits corresponding to the TAP selection signal that control the selection of the user TAP and the EDA tool TAP; and
a programming module connected to the control register that updates the control register based on a pre-determined criterion.
4. The system for testing memory blocks of claim 1 , further comprising a dual-TAP output circuit that selects output of one of the user TAP and the EDA tool TAP based on the TAP selection signal, wherein output of the EDA tool TAP is selected to provide test data to the memory testing module.
5. The system for testing memory blocks of claim 4 , wherein the dual-TAP output circuit includes at least one multiplexer to select the output of one of the user TAP and the EDA tool TAP.
6. The system for testing memory blocks of claim 1 , further comprising a deselecting module coupled with the EDA tool TAP that is capable of selecting one or more memory blocks of the plurality of memory blocks and at least one operating mode of a plurality of operating modes of the testing phase.
7. A method for testing a plurality of memory blocks in a System on Chip (SOC) having a user TAP and an Electronic Design Automation (EDA) tool TAP, the method comprising:
selecting the user TAP at an outset of a testing phase;
generating a TAP selection signal with a secured logic block, wherein the secured logic block is associated with the user TAP and wherein the secured logic block prevents non-privileged access to the plurality of memory blocks via the EDA tool tap;
selecting the EDA tool TAP based on the TAP selection signal to provide test data during the testing of the plurality of memory blocks; and
testing the plurality of memory blocks using the EDA tool TAP.
8. The method for testing a plurality of memory blocks of claim 7 , wherein generating the TAP selection signal comprises using at least one of a sequential logic block and a combinational logic block.
9. The method for testing a plurality of memory blocks of claim 7 , wherein the step of selecting the EDA tool TAP comprises deselecting the user TAP.
10. The method for testing a plurality of memory blocks of claim 7 , further comprising deselecting the user TAP and the EDA tool TAP based on the TAP selection signal after completion of the testing phase.
11. The method for testing a plurality of memory blocks of claim 7 , further comprising selecting one or more memory blocks of the plurality of memory blocks and at least one operating mode of a plurality of operating modes of the testing phase.
12. A method for testing a plurality of memory blocks in a System on Chip (SOC) having a user test access port (TAP) and an Electronic Design Automation (EDA) tool TAP, wherein the EDA tool TAP is used to access and test memory blocks of the SOC, and wherein the user TAP and the EDA tool TAP are accessed using one set of JTAG pins including a TDI, TCK, TMS and TRST pin, the method comprising:
selecting the user TAP at an outset of a testing phase;
generating a TAP selection signal with a secured logic block, wherein the secured logic block is associated with the user TAP and prevents non-privileged access to the plurality of memory blocks via the EDA tool tap, and wherein the TAP selection signal is gated to the TMS pins of the user TAP and the EDA tool TAP;
selecting the EDA tool TAP and deselecting the user TAP with the TAP selection signal;
receiving test data at the TDI pin;
testing the plurality of memory blocks with the test data using the EDA tool TAP;
deselecting the EDA tool TAP upon completion of the testing phase; and
blowing at least one fuse in the secured logic block so that secured logic block cannot assert the TAP selection signal, thereby disabling access to the EDA tool TAP so that the memory blocks can no longer be accessed via the EDA tool TAP.