Methods for at-speed testing of memory interface
View Patent ↗Methods for at-speed testing of a memory interface associated with an embedded memory comprise two write operations in succession, two read operations in succession, and a capture operation using scan cells. The write and read operations are performed during a single clock burst, two separate clock bursts in a clock signal, or two separate clock bursts in separate clock signals.
1. A method for testing a memory interface at-speed, comprising:
scanning in input data;
performing one or more write operations on a memory using the input data during a first clock burst, the memory being associated with the memory interface being tested;
performing one or more read operations on the memory during a second clock burst, the one or more read operations starting after the one or more write operations are completed;
capturing output data from the memory interface with scannable memory elements during the second clock burst, the output data corresponding to the one or more read operations; and
scanning out the output data from the scannable memory elements.
2. The method recited in claim 1 , wherein the first clock burst precedes the second clock burst in a same clock signal.
3. The method recited in claim 1 , wherein the first clock burst and the second clock burst are in separate clock signals.
4. The method recited in claim 1 , wherein the capturing can be suppressed when the memory interface outputs unknown values.
5. The method recited in claim 1 , wherein the input data include, if the memory has a plurality of write ports, a write port selection code for selecting a write port from the plurality of write ports to perform the one or more write operations during the first clock burst.
6. The method recited in claim 1 , wherein one or more clock cycles in the first clock burst, the second clock burst or both run at a slower frequency than the other clock cycles in the same clock burst.
7. The method recited in claim 1 , further comprising:
launching initialization information before the one or more write operations, the initialization information being included in or derived from the input data.
8. The method recited in claim 7 , wherein the initialization information comprises an initialization address and an initialization data word.
9. The method recited in claim 8 , wherein the one or more write operations comprises:
writing the initialization data word to a first memory location corresponding to the initialization address; and
writing a final data word to a second memory location corresponding to a final address.
10. The method recited in claim 9 , wherein the initialization address and the final address are derived using a reference address, the reference address being included in the input data and stored in an address register.
11. The method recited in claim 9 , wherein the one or more read operations comprise:
reading the initialization data word from the first memory location corresponding to the initialization address; and
reading the final data word from the second memory location corresponding to the final address.
12. The method recited in claim 9 , wherein the one or more read operations comprise:
reading the final data word from the second memory location corresponding to the final address; and
reading the initialization data word from the first memory location corresponding to the initialization address.
13. The method recited in claim 7 , wherein the initialization information comprises an initialization data word.
14. The method recited in claim 13 , wherein the one or more write operations comprises:
writing the initialization data word to all memory locations; and
if a write enable signal is active, writing one or more final data words to one or more memory locations.
15. The method recited in claim 14 , wherein the one or more read operations comprise:
reading from a first memory location corresponding to a first address; and
if a read enable signal is active, reading from a second memory location corresponding to a second address.
16. A circuit, comprising:
a memory;
a memory interface associated with the memory; and
a plurality of scannable memory elements configured at least to scan in data for performing a method for testing the memory interface at-speed, the method comprising:
scanning in input data;
performing one or more write operations on the memory using the input data during a first clock burst;
performing one or more read operations on the memory during a second clock burst, the one or more read operations starting after the one or more write operations are completed;
capturing output data from the memory interface during the second clock burst, the output data corresponding to the one or more read operations; and
scanning out the output data.
17. The circuit recited in claim 16 , further comprising:
a sequencer configured to generate control signals for each clock signal.
18. The circuit recited in claim 16 , wherein the first clock burst precedes the second clock burst in a same clock signal.
19. The circuit recited in claim 16 , wherein the first clock burst and the second clock burst are in separate clock signals.
20. The circuit recited in claim 16 , wherein the capturing can be suppressed when the memory interface outputs unknown values.
21. The circuit recited in claim 16 , wherein the input data include, if the memory has a plurality of write ports, a write port selection code for selecting a write port from the plurality of write ports to perform the one or more write operations during the first clock burst.
22. The circuit recited in claim 16 , wherein one or more clock cycles in the first clock burst, the second clock burst or both run at a slower frequency than the other clock cycles in the same clock burst.
23. The circuit recited in claim 16 , wherein the method further comprising:
launching initialization information before the one or more write operations, the initialization information being included in or derived from the input data.
24. The circuit recited in claim 23 , wherein the initialization information comprises an initialization address and an initialization data word.
25. The circuit recited in claim 24 , wherein the one or more write operations comprises:
writing the initialization data word to a first memory location corresponding to the initialization address; and
writing a final data word to a second memory location corresponding to a final address.
26. The circuit recited in claim 25 , wherein the initialization address and the final address are derived using a reference address, the reference address being included in the input data and stored in an address register.
27. The circuit recited in claim 25 , wherein the one or more read operations comprise:
reading the initialization data word from the first memory location corresponding to the initialization address; and
reading the final data word from the second memory location corresponding to the final address.
28. The circuit recited in claim 25 , wherein the one or more read operations comprise:
reading the final data word from the second memory location corresponding to the final address; and
reading the initialization data word from the first memory location corresponding to the initialization address.
29. The circuit recited in claim 23 , wherein the initialization information comprises an initialization data word.
30. The circuit recited in claim 29 , wherein the one or more write operations comprises:
writing the initialization data word to all memory locations; and
if a write enable signal is active, writing one or more final data words to one or more memory locations.
31. The circuit recited in claim 30 , wherein the one or more read operations comprise:
reading from a first memory location corresponding to a first address; and
if a read enable signal is active, reading from a second memory location corresponding to a second address.