System and method for maintaining RAM command timing across phase-shifted time domains
According to one exemplary embodiment, a RAM employing system includes a RAM and a RAM controller coupled to the RAM. The RAM employing system further includes a command queue, which is configured to receive time encoded RAM commands from the RAM controller. The RAM is configured to retrieve, decode, and execute each of the time encoded RAM commands in the command queue.
1. A RAM employing system comprising:
a RAM coupled to a RAM controller;
a command queue configured to receive a plurality of time encoded RAM commands from said RAM controller;
wherein said RAM is configured to retrieve, decode, and
execute each of said plurality of time encoded RAM commands in said command queue, and wherein said time encoded RAM commands are transferred to said command queue using a flow-controlled bus, such that a phase-shift results between a time domain of said RAM and a time domain of said RAM controller.
2. The RAM employing system of claim 1 , wherein each of said plurality of time encoded RAM commands is encoded with timing information relative to an immediately preceding RAM command in said plurality of time encoded RAM commands.
3. The RAM employing system of claim 2 , wherein said timing information is decoded to determine an execution delay period between the execution of a RAM command and said immediately preceding RAM command.
4. The RAM employing system of claim 3 , wherein said execution delay period is loaded into a counter to provide the required execution delay period.
5. The RAM employing system of claim 1 , wherein said command queue is included in said RAM.
6. The RAM employing system of claim 1 , wherein said RAM is a dynamic random access memory (DRAM).
7. The RAM employing system of claim 1 , wherein said RAM controller can transfer said plurality of time encoded RAM commands directly into said command queue.
8. The RAM employing system of claim 1 , wherein said command queue is a first-in, first-out (FIFO) queue.
9. A method for maintaining random access memory command timing between a RAM controller and a RAM, said RAM including a command queue, said method comprising the steps of:
receiving a plurality of time encoded RAM commands in said command queue;
retrieving one of said plurality of time encoded RAM commands from said command queue;
decoding said one of said plurality of time encoded RAM commands;
executing said one of said plurality of time encoded RAM commands, wherein said plurality of time encoded RAM commands are transferred to said command queue using a flow controlled bus, such that a phase-shift results between a time domain of said RAM and a time domain of said RAM controller.
10. The method of claim 9 , wherein each of said plurality of time encoded RAM commands is encoded with timing information relative to an immediately preceding RAM command in said plurality of time encoded RAM commands.
11. The method of claim 10 , wherein said decoding step further comprises decoding said timing information to determine an execution delay period between the execution of said one of said plurality of time encoded RAM commands and said immediately preceding RAM command.
12. The method of claim 11 , wherein said execution delay period is loaded into a counter to provide the required execution delay period.
13. The method of claim 9 , wherein said RAM controller can transfer said plurality of time encoded RAM commands directly into said command queue.
14. The method of claim 9 , wherein said RAM is a dynamic random access memory (DRAM).
15. The method of claim 9 , wherein said command queue is a first-in, first-out (FIFO) queue.