Asynchronous/synchronous interface
View Patent ↗The present disclosure includes methods, and circuits, for operating a memory device. One method embodiment for operating a memory device includes controlling data transfer through a memory interface in an asynchronous mode by writing data to the memory device at least partially in response to a write enable signal on a first interface contact, and reading data from the memory device at least partially in response to a read enable signal on a second interface contact. The method further includes controlling data transfer in a synchronous mode by transferring data at least partially in response to a clock signal on the first interface contact, and providing a bidirectional data strobe signal on an interface contact not utilized in the asynchronous mode.
1. An apparatus, comprising:
a memory interface including:
a first memory interface contact;
a second memory interface contact; and
a third memory interface contact; wherein the memory interface is configured to:
switchably operate in either an asynchronous mode or a synchronous mode;
receive a signal on the second memory interface contact as a read enable signal in the asynchronous mode and as a write/read signal in the synchronous mode; and
operate in the synchronous mode utilizing one additional contact of the memory interface than a quantity of contacts utilized in the asynchronous mode.
2. The apparatus of claim 1 , wherein the one additional contact of the memory interface is configured to send and receive a bidirectional data strobe signal.
3. The apparatus of claim 1 , wherein the memory interface is configured to utilize two signals complementary to memory interface control signals utilized in the asynchronous mode.
4. The apparatus of claim 3 , wherein one of the two signals complementary to memory interface control signals utilized in the synchronous mode includes a complementary clock signal.
5. The apparatus of claim 1 , wherein the memory interface is configured to receive a signal on the first memory interface contact as a write enable signal in the asynchronous mode and as a clock signal in the synchronous mode.
6. The apparatus of claim 1 , wherein the memory interface is configured to detect for a clock signal on the first memory interface contact at least partially in response to detection of a chip enable signal on a different memory interface contact.
7. An apparatus, comprising:
a memory device; and
control circuitry configured to:
write data to the memory device in an asynchronous mode in response to a write enable signal received on a first interface contact;
transfer data to the memory device in a synchronous mode in response to a clock signal received on the first interface contact and a signal received on an interface contact not utilized in the asynchronous mode; and
respond to an unasserted state of a read enable signal as a write enable signal while in the synchronous mode.
8. The apparatus of claim 7 , wherein the signal on the interface contact not utilized in the asynchronous mode is a bidirectional data strobe signal.
9. The apparatus of claim 7 , wherein a quantity of interface contacts utilized in the synchronous mode is only one more than the quantity of interface contacts utilized in the asynchronous mode.
10. The apparatus of claim 7 , wherein the control circuitry is configured to control switching between the asynchronous mode and the synchronous mode responsive to a mode selection signal.
11. A method, comprising:
switchably operating a memory interface in a synchronous mode and an asynchronous mode, wherein operating the memory interface in the synchronous mode utilizes one additional contact of the memory interface than a quantity of contacts utilized in the asynchronous mode by:
operating the memory interface in the asynchronous mode utilizing a read enable signal on a second contact of the memory interface; and
operating the memory interface in the synchronous mode utilizing a read-write signal on the second contact of the memory interface.
12. The method of claim 11 , further comprising:
operating the memory interface in the asynchronous mode utilizing a write enable signal on a first contact of the memory interface; and
operating the memory interface in the synchronous mode utilizing a clock signal on the first contact of the memory interface.
13. The method of claim 11 , further comprising powering up the memory interface in the synchronous mode.
14. The method of claim 11 , further comprising powering up the memory interface in the asynchronous mode.
15. The method of claim 11 , further comprising switching from the asynchronous mode to the synchronous mode at least partially in response to detection of a clock signal on a memory interface contact of the memory interface.