Time division multiplexed multiport memory implemented using single-port memory elements
View Patent ↗Integrated circuits having single-port memory elements may be provided. The single-port memory elements may be controlled using a control circuit to emulate multiport functionality. In one suitable embodiment, the control circuit may be an arbitration circuit configured to execute a memory request as soon as it is received by the arbitration circuit. Requests received while a current memory access is being performed may be put on hold until the current memory access has been completed. In another suitable embodiment, the control circuit may be a sequencing circuit configured to service memory access requests from a synchronous port and an asynchronous port. Memory access requests received at the synchronous port may be serviced immediately, whereas memory access requests received at the asynchronous port may be synchronized to an internal memory clock signal and may be serviced after a preceding memory access request associated with the synchronous port has been serviced.
1. A method of operating memory having first and second ports, comprising:
receiving a first memory access request at the first port;
receiving a second memory access request and an associated clock signal at the second port;
with a control circuit, detecting a clock edge in the clock signal at the second port; and
in response to detecting the clock edge, using the control circuit to generate an additional clock signal.
2. The method defined in claim 1 , further comprising:
using the additional clock signal to latch the first memory access request.
3. The method defined in claim 1 , wherein detecting a clock edge in the clock signal comprises detecting a rising clock edge in the clock signal at the second port.
4. The method defined in claim 1 , further comprising:
receiving another clock signal that is associated with the first memory access request at the first port.
5. The method defined in claim 1 , further comprising:
in response to detecting the clock edge, immediately servicing the second memory access request.
6. The method defined in 1 , wherein the memory comprises an array of single-port memory elements.
7. The method defined in claim 2 , wherein using the additional clock signal to latch the first memory access request comprises sampling the first memory access request on the rising and falling clock edges of the additional clock signal.
8. Circuitry, comprising:
a plurality of memory elements;
a first port that receives a first memory access request;
a second port that receives a second memory access request;
a control circuit that generates a control signal that determines which one of the first and second memory access requests is to be selected for fulfillment at the plurality of memory elements; and
a multiplexing circuit having a first input that receives the first memory access request from the first port, a second input that receives the second memory access request from the second port, and a control input that receives the control signal.
9. The circuitry defined in claim 8 , wherein the plurality of memory elements comprises a plurality of single-port memory elements.
10. The circuitry defined in claim 8 , wherein the first port also receives a first clock signal, and wherein the second port also receives a second clock signal that is different than the first clock signal.
11. The circuitry defined in claim 10 , wherein the control circuit is configured to receive the second clock signal but not the first clock signal.
12. The circuitry defined in claim 10 , wherein the control circuit is configured to generate an additional clock signal in response to detecting a clock edge in the second clock signal.
13. The circuitry defined in claim 10 , further comprising:
a first input latch that is clocked by the first clock signal and that latches the first memory access request; and
a second input latch that is clocked by the second clock signal and that latches the second memory access request.
14. A method for operating memory circuitry having first and second ports, comprising:
receiving a first memory access request at the first port;
receiving a second memory access request and an associated clock signal at the second port;
with a control circuit, servicing the second memory access request in response to detecting a clock edge in the clock signal; and
with a buffer, temporarily storing the first memory access request and generating an output valid signal indicative of whether the buffer is empty.
15. The method defined in claim 14 , wherein generating the output valid signal with the buffer comprises deasserting the output valid signal when the buffer is empty and asserting the output valid signal when the buffer is not empty.
16. The method defined in claim 14 , further comprising:
with a request synchronizer, receiving the output valid signal and outputting a corresponding synchronization signal to the control circuit.
17. The method defined in claim 16 , further comprising:
when the second memory access request is fulfilled, processing the first memory access request only if the synchronization signal is asserted.
18. The method defined in claim 16 , further comprising:
with the control signal, generating an additional clock signal in response to detecting the clock edge.
19. The method defined in claim 18 , further comprising:
controlling the request synchronizer with the additional clock signal.
20. The method defined in claim 14 , wherein the first and second memory access requests access an array of single-port memory elements in the memory circuitry.